Welcome to today's lecture on industrial hydraulics and pneumatics. Now, today's lecture will be on pneumatic system and components and this will be introduction to that and the particular topic will be air preparation, compressor and accessories. Now, contrary to hydraulic system, pneumatic systems use pressurized compressible fluids. This means that in case of oil hydraulics, the fluid is compressible and incompressible and a pressurized fluid inside a conduit acts as a elastic body. Maybe it is like a solid member. Therefore, in that case particularly where with closed circuit, there is no change in pressure once it is the fluid is trapped. Of course, that depends on the load required we are moving, but in case of this compressible fluids air or gas, what happens the fluid after utilization it is exhaust to the nature and in that way pressure of the fluid reduces. So, for the constant pressure system it is not that much suitable also it is not suitable for very high power. So, but for the small applications small power applications tools and others you will find this pneumatic system is very useful and air is free of cost you are getting a free of cost only thing you have to prepare the air for utilizing into a system. Now, although other gases are used, but air is the most common compressible fluid although some gases are also used in pneumatic drives specially where the gas itself is one of the product or by product where the system is being used. However, air is the environment friendly chief safe readily available fluid media for pneumatic applications. For general purpose actuator drives manageable with low pressure usually 2 mega Pascal, 2 mega Pascal means it is 20 kg per centimeter square and you can see just a little above absolute pressure. Pneumatic system is preferred over hydraulic system where pressure may be as high as 80 mega Pascal. This means that in hydraulic system we can go up to 80 mega Pascal, but in normal case as you know that in oil hydraulics 20 to 25 mega Pascal is very common 80 mega Pascal is very special applications, but it is possible there. However, position or actuation at control velocity is not achievable with compressible fluids. This is a drawbacks with compressible fluids if you would like to control the position control or the velocity control then it is very difficult to achieve for a small magnitude small zone it is possible relatively larger zone larger range where the hydraulic fluid will be more useful. Pneumatic application in such areas are rare and where hydraulic oil cannot be used due to environment reason. Actually, we had in some cases it is compromised where the hydraulic oil cannot be used due to environmental reasons. So, better to go for pneumatic applications say for example, in case of food processing industry. Also less accurate performance is acceptable. In pneumatic system compressors typically the vane, lobes, screw or cylindrical piston type positive displacement machines are used to compress and store the air. Now here again I would like to mention that in case of pneumatics or the compressible fluid the machines the hydrostatic units are used that is pump and motor those are in nature positive displacement. This means that their volume displacement ideally is will be equal to their geometric displacement. It is not like hydro kinetic machines. For example, a blower if we consider a blower it is not a positive displacement machines unless it is a positive displacement machine is being used for a blower. So, I think you understand what is positive displacement that if you calculate the geometric volume displacement ideally that will displace the same amount of fluid. Now in case of compressible fluid definitely this volume is being compressed that means when the pressure is increasing that volume is being compressed. So, by the pump that much amount of is being pumped whereas it might be of higher pressure and then it is going into the reservoir that means collector and gradually you will find that if you ask that how what is the volume of air inside the reservoir. The answer is that what is the geometric volume of the reservoir that is the volume at any point only thing pressure is gradually being increased as you running the compressor. In case of oil hydraulics it is not that this means that in the conduit obviously always you have to say volume is equal to the that amount of volume. But you can say the your positive displacement machine also delivering the same amount of volume in case of the air it is not or gases. The compressed and stored air or gas used in operating pneumatic devices when whenever required by tapping in a regulated manner the air from storage vessel tank normally attest to and or integral with the compressor. This means that it is not that you are directly pumping this air to the system. In case of hydraulic system most of the cases you will find that there is no reservoir in between. If you consider at all there is a reservoir in between that you may consider the accumulator very small reservoir. But in case of pneumatic system there will be always a reservoir that means first the air is stored in a reservoir or receiver and then the air is used for the system. You can simply tap the air with the help of a regulator and can use it. Usually compressor is stopped at a set higher pressure than maximum operating pressure. Say for example, you are using a in your pneumatic systems in the in your works of or industry for machines maximum is 1.5 megapascal. Maybe you are storing that air inside the reservoir at 2 megapascal. It automatically starts again when the stored air pressure reaches a minimum set value. This means that say for the reservoir 2 megapascal is the upper limit. So, when the pressure inside this reservoir will reach at 2 megapascal it will be automatically stopped and probably it will start again the minimum pressure what you need for the operations. Say for example, it might be 1 megapascal or might be 0.7 megapascal whereas maximum for some devices is 1.5. So, when it will reach that 0.75 or 1 megapascal it will start. But one thing we should remember that if we had to use that instrument or device which is which requires 1.5 megapascal then we have to set the lower pressure as 1.5 megapascal. So, then range will be 1.5 and 2 megapascal and also usually there will be a time set otherwise the compressor will run always. So, that is a design criteria that you have to design in a system suppose you are using this always it is 1.5 megapascal and very continuous consumption is there. Probably you have to set the compressor reservoir side in such a way at least your compressor can be stopped for 5 minutes while it is running otherwise question of heat generation and other problems are there. Usually from a centralized store air is supplied to various locations of an entire industrial plant. It might be single reservoir in it might be multiple usually not more than 2 reservoir are used to supply the plant. If the plant is very big sometimes it is more than 1 reservoir is used. After filtering and before the end applications a fine mist of lubricant is mixed to the air to prevent air in the moving components. Now usually if you find that air operated devices say for example air operated screwdriver. So, you just put say if you have observed in automobile industry they had to tight the screw may be in a line in a assembly line they have to tight a screw 100 screw per minutes say just for an example in that case every screw driving by the screwdriver is not possible. You will find the pneumatic screwdriver is there and it is set like that for this screwdriver device when the maximum torque is reached it will automatically slip. So, now in that case that is connected with a pneumatic systems. Now usually this moving component inside definitely there is moving component there is no separate lubricant inside. So, with the air you have to mix that lubricant normally with the air not with the other gas and other things in case of gas also you have to take care of that what type of lubricant you can mix. In case of air ordinary lubricant can be mixed, but before that your air should be all dust free and it should be dry. That means no moisture is allowed within this air. So, after filtration or such preparations again you have to mix with oil that is important this is required to lubricate the moving components. Air dryer is also used to eliminate moisture from air. So, as I have told that you have to use an air dryer a muffler is put at the exhaust to reduce noise. Now muffler means the silencer is usually used at the exhaust point. Now when you are using a system then the device you are driving. So, it might be after the replication there should have muffler. That means muffler in some cases you will find is an integral component or of the pneumatic device which you are using, but there is also inline muffler just to reduce the noise level. When the air is flowing through these components there will be noise you can you know it that when air blows to even if in nature also when air blows you can heard the sound. So, to reduce such noise there will be muffler or which is called silencer. Now next slide we will look into a pneumatic system I think that you cannot read this not that clear, but I would say that here there is a this is the compressor unit. This compressor unit is having the this is the driving unit and then may be filtered then cooler and after then this is the main reservoir and here there is a dryer at that point there is a dryer. And if you look into this what we find we have two parallel system connected to the same line. As I told in case of if you find that air is being utilized in such a way if you use single compressor then it will run it has to run for I mean continuously that is not permitted to look into the life of the compressor because during such process use air is generated this is due to the molecular action in within this air. Now, you one can have one compressor and may be two reservoirs or might be there is a big reservoir and two compressor this is usually safe system to use two compressor rather than manipulating something with the reservoir. And then it is also shown here say these are the two work point, but usually there will be huge I mean many work point. Now, these tools are called pneumatic tools and here this is the regulator filter and lubricator are used at a different point. Say each and every before each and every pneumatic tools you will find a filter regulator and lubricator is being used. So, this is a very schematic and very general system for a pneumatic there will be a pipeline throughout the industry. Now, in preparation of usable pressurized compressible fluids we need following major components one is that definitely a compressor is nothing, but a pump which is pumping the air or gas a receiver or a reservoir tank starting unloader and controller this is very important we will come to that what it is then we need filters. Now, this filters is not again the suction strainer there will be there after the compression we need a filter online filter to make the air dust frame. Then we need definitely a regulator and valves we need a lubricator as mentioned mufflers and silencer after cooler we need a after cooler means usually the air before entering into the machine we need to cool it because the air we exhaust into nature. So, we do not need after cooling means it is not after using this air in case of oil hydraulics what is done usually after the application we take back that oil to the reservoir and before that we use the cooler. In that case before utilization a cooler is used, but after cooler term is used after all process that mean drying etcetera then the cooling is done and finally it is used. Then air dryers and we need indicators that is pressure temperature etcetera wherever required also sometimes a set of pressure and indicator is kept to inspect the pressure and temperature at different point that is sometimes needed because there will be very big pipeline for the supply of the air pressure sometimes it is very difficult to find where the pressure drop actual pressure drop is occurring. So, for that purpose we need separate unit pressure and in temperature indicator. Now, we will come to this components what are the components and the most important is the compressor now if you look into the types of compressor then most common is the reciprocating piston compressor and then again the piston compressor and diaphragm compressor diaphragm compressor means in that case a diaphragm is being moved by some means and that also compresses the air. But then rotary piston compressor this is sliding vane rotary compressor you see one is that rotary piston and another is called rotating piston anyway we a rotary piston means usually a volume is trapped and then that is compressed by compressing the variable area. In case of reciprocating normally the stroke length varies area does not vary whereas, in case of rotary pistons you will find area is varying say gear pump like that low pump etcetera. Then this rotary compressor again sliding vane rotary compressor two axles screw compressor say like gears and etcetera that also fall in this category and roots blow over and then another it is a flow compressor that radial flow compressor axial flow compressor these are two different types of separate flow compressor. But we shall concentrate on these are the some special types these are used for not normally such big system very small systems these are used. But reciprocating piston compressor this is very common particularly piston type and among the rotary pistons both sliding vane and two axles screw or the gear type compressor are mostly used. So, we shall concentrate on these items only. Now reciprocating type reciprocating cylindrical single piston cylinder type compressor may be of single may be of single or multiple this means that it has meaning that single means suppose there is a two pistons that is not that may not be two stage only two pistons are being used they are compressing the air at a same pressure whereas, you may find two pistons but that is two stage that mean in first stage one piston is compressing the air and second stage other piston the compressing that air that means suppose you have to raise the pressure up to two megapascal first piston may be raising the pressure not exactly half it might be 0.75 megapascals and then second piston that compressed air is being further energized to make the pressure two megapascals. So, that is called two stage similarly there may have three stage also. So, we use single or multiple stage now if I look into this figures the left hand side this figure a that shows a reciprocating two stage compressor but before that I would say that depending on pressure capacity if the pressure capacity is one megapascal usually in that case we can go for single stage then it is if it is 3.5 then two stage then if it is 17.5 megapascal it is in the higher side and as well we have to go for three stage and for 35 megapascal this is four stage. Now, 35 megapascals means it is very high the this is a definitely special applications normally interest of fluid power we use normally 25 say 21 megapascal is equal to 3000 psi 21. So, 35 means it is more than 4000 psi normally there is no such applications but if it is required then we have to go for four stage and normally reciprocating type is not suitable for that usually screw compressor is used for such compressions. Anyway if we come to this compressing machines what we find here is one set of piston cylinder here is another set of piston cylinder and here this is the third. If you look into these two these two are identical even they are having the same discharge valves suction valve these are same. Now, these two cylinders together pumping the air for the first stage that means from the nature the air is being taken and that is being pumped that is being compressed to reach a certain amount of pressure say for example, two stage mean this is 3.5 probably it is being raised up to 1.5 only then this total compressed air now that total compressed air what the two piston has done that volume has reduced that for that only a single piston can pressurize that amount of air further to 3.5 and that is the second stage piston cylinder. Now, the other details you can study of your own from this figure. Now, if we look into this principle you know it but basic principle is that this while it is reciprocating then there will be one is that delivery and one is the inlet and one is the delivery say it is rotating in this direction. So, only the inlet port is open and when it is rotating the other half then it is being delivered. This is the simplest form of this reciprocating system and the same thing is followed here just only suction and compression. So, in and out delivery. So, if you look in this way for one cycle only suction. So, half the cycle suction and half the cycle the delivery. So, you can put two cylinder single stage but two cylinder in such a way that is continuously it is supplying the air to dissipate a generated heat due to molecular reaction in the air being compressed. If you compress the air you will find that heat is being generated cooling system natural air draft to forced water cooling are employed. That means, for the small compressor you can simply use a fan just to cool and this reservoir as well as the compressor outside is made body is made with additional heat dissipation area. That means, fins are used even if the tank you will have you may find that additional fins may be used just to cool it. But for higher pressure may be say in case of two stage three stage and four stage you need to have forced cooling and usually cooling by water is done. Other fluid can be used in case of say refrigerator systems if some cooling is required no water is used. But in case of general compressor for big compressor which is used in industry usually you will find the oil is being used. And normally if you look into this pistons outside there are pockets these pockets are filled with water. That means, water is always flowing through these pockets that is called jacket. The piston is having the space through which the water is moving that means, while it is being compressed then itself it is being cooled to some extents. And after that also there is a separate cooler is used to cool the air. Now this is a photographic view I am not describing the components. You can understand this for the same machines these two are for first stage and this is for the second stage usually a spring is provided just for the return stroke. If you look into the geometric of this cranks after another things. So, you need to have some return. So, the springs are buffer springs are usually used. And if you look into the capacity with a 0.54 meter cube capacity reservoir storage tank you can understand this 0.54 meter cube. So, 1 meter cube is equal to how much 1000 liter. And here 0.54 means half of that 500 liters around 540 liters around this 1 meter cube the volume and compressing capacity of 1.3 meter cube per minute. So, this is called compressing capacity not the flow capacity we should call compressing capacity. At 1.23 megapascals power of the motor is 6.25 kilowatt typical. If you calculate this pressure into flow rate it will not be 6.25. But usually efficiency of compressors is relatively poor that is why at least you need 6.25 kilowatt typical. We will calculate the sizing of such in compressors. Now an air compressor is usually made auto control to start run supply pressurized air as needed. And stop when receiver is filled with maximum capacity that is pressure and be ready to start again when the pressure reaches at its lower limit. A few methods are employed for such control. Pressure switch control is one of them. Once a pressure is established after first start up a starting unloader look at this term it is called starting unloader is required to prevent the established air pressure from pushing back against the compressor preventing it from coming up to speed. The meaning of the sentence is that you have compressed the air and the compressor is stopped. Now if you look into this line from the where the rotary piston rotating piston is compressing the air from that point to compressor path is completely filled with pressurized pressure. Now it is cut off from the reservoir. Resurver is supplying the air and that pressure when it is reduced then the compressor has to start but when the compressor is going to be start the trapped air to that will create a problem to start off the compressor. So you need to release that pressure within that short path that is from the compressor head to the reservoir entry point that is called starting unloader. Now we use here the pressure switched type. Now if you look into this figure 4 this is the pressure switch what is if you look into this this is the compressor head say air inlet is here. Now this air is going and here is a non-return valve connected to the reservoir receiver and then air is being compressed and forced with force it is being entered into the reservoir. Say it is 2 megapascal. Now when such pressure is this is this is the reservoir is being filled then with a set pressure this switch is there and that gradually disconnect the motor and your compressor will stop but if you look into this path then this path will remain filled with the pressurized air. Now to relive that what is there with this pressure switch there is a lever that operates another valve actually there is another valve sort of things which allowed or relive the compressed air between this path. Now here apparently it is a open path maybe here maybe some non-return sort of valve might be there which is not shown here but what happens when this machine is stopped the reservoir is having it is maximum pressure say 2 megapascal then this motor is stopped as well this path is made free. So, that next time when the signal comes it starts operating without any trouble for that we need a unloader. So, this is you can say the starting unloader when motor is off by pressure switch it also bleed off it is this operation is called bleed off the trapped air between the piston head and receivers check valve this is the receivers check valve it enables the compressor to start again whenever needed. Now there is another type of unloader which is centrifugal type the basic principle is that the centrifugal mass is attached to a rotating member this is with the compressor crankshaft then when it reaches then it operates the switch in the same way the pressure switch operates. Now in such system greater production is ensured as the unloader valve is operated by the compressor itself rather than the pressure switch such normal controls described above are used where the compressor running time is 50 percent to 80 percent of total working time. Now for the compressor starting frequently say within every after 6 minutes or running time exceeds 80 percent of total time more sophisticated constant speed control is adopted that is usually nowadays with electronics control some controller is used to automatically cut off the compressor start the compressor and in between unload or the relief the trapped air between the compressor head to the reservoir inlet. Now this 6 minutes figure what I understand this is usually a figure at least you should keep a 6 minutes time off between 2 running times otherwise sufficient cooling will not be there. Now we shall consider another type of compressor which is called screw compressor. Now this is rotary positive displacement because if this is like an hydraulic screw pump here also the screw 2 screws are rotating but if you look into this this might be rotating at this 2 screws are rotating at the different speed not at the same speed and this is the entrapped volume is being compressed it is taking in and it is going out in the other side that means inlet and outlet is usually axial in case of the screw type compressor if we look into this figure then we will look into this it looks something like this these 2 profiles are not same I mean this profile and this profile are not same here is also it is not very clear from this figure but from this side view we can look into this. And what we find then there is a timing gear this is required to for inlet outlet control the cooling jackets is there and this is not symmetric asymmetric rotors anti friction and rolling bearings are used in between. Now this is the what is found that this type of compressor is having much better life and it can perform better in high pressure. So you will find that of course if you think in terms of volume that will be less in comparison to the reciprocating type. So where the moderate volume is required with very high pressure may be the screw compressor is the better than the cylindrical piston type as in screw type the entrapped volume gradually squeezed to smaller and specialized volume for to be stored in reservoir usually it is axial usually you will find the axial inlet and the outlet in the radial directions but at the other end and these are the cooling jackets. Now to assess and size of such a machine 0.7 mega meter cube per second that is the capacity of storing 0.85 mega Pascal is typical for a single stage screw compressor. So single stage screw compressor means it is not very high 0.85 mega Pascal and 0.7 meter cube per second. So this volume not that small in that way maybe this value may not be correct I have to check it 0.7 meter cube is a very big volume. Then if we look into the side view of this screws compressor you as I told these are not symmetric profiles it looks like something like this one is that thinner another is wider and here what we find this we have 4 lobes that means it might be 4 start screw and here what we find 1, 2, 3, 4, 5, 6 here 4 and here 6 that is why you will find that these two are rotating at different speed and we need a separate gear of the same ratio at the end just to match that. Now you may ask why it is different it is seen that this will give better performance as for the volume is concerned and as this is being of different size and this is the may be to optimize the capacity it is better. Suppose if we use here 4 and here 4 you may find that it is not the optimum design using 6 here and because this is the main pocket as if this pocket is being composed by this is the piston you can consider this is cylinder this is piston. So, 4 piston is compressing the air within 6 cylinder roughly you can say like that, but actual path is like that it is a helical path through which the compressed air is being moved separated by the contact at these two profiles and by the casing. It looks like Novikov gear if you look into this side view it looks like a gear not exactly Novikov gears it is different, but as if it looks like a gear. In fact gear type compressor may be regarded as short screw compressor with different inlet outlet arrangement. Now obviously if you look into this if you like to compare with this gear sorry this screw compressor with the gear type compressor definitely this is also helical that means helix gear as if, but this length of this screw cone here what is the length in this case length is very small as well you will find the inlet outlet is like that, but this is also of different profile as you can see you can compare this, but remember this one is the gear type or sometimes it is called lobe type and whereas this is the cross section of the screw type compressor. Now here again I have shown some say this is gear type and similar is the lobe type, but in case of lobe type usually these profiles are same both the profiles are same and number of lobes will be same, but basic principle this lobes and gear are the same principle and you will find inlet outlet is like that, but remember like the gear pump this is say suppose this is rotating in this directions then this will be inlet and this will be outlet normally if it is rotating like in this directions then people confuses perhaps air is flowing like this in case of gear pump also, but it is not like that. The air is coming in then it is being trapped and it is going out if we remember recall that comparing with the gear pump here from this contact point and this three contact line or point on this plane if we consider with the rotation this area will be gradually it will reduce that means this volume will be compressed. So, this compressed air will now go inside it will be trapped and then it will be delivered in the other sides and this is the side view of this lobe type compressor. Inlet outlet as different this is completely radial in case of screw type you will find this is going like this and probably outlet will be like this. So, the length to be considered as a width of the gear in this case also the teeth may be straight and not helical say here somewhat it is helical one can use the straight teeth for the gear type compressor and lobes are always mostly you will find may be straight also here of course it is showing that as if it is helical it might be straight also. In this lobe there is no space within the lobe, but here this space is given it might be this is all can be used for cooling purpose also. However, capacity wise the screw type is superior although has more friction losses due to friction are minimized using liquid lubricant which also carry heat as well as mixed with the compressed and pre filtered air. Now, in such in such compressor you have to lubricate this. So, that lubricant is mixed with the air. So, it might be we have to reduce the air first demodernize the air before entering into such compressor and then or else the well being mixed that will not be separated we have to use the separator or filter in such way the oils are not being separated because the oil mixing is being to some extent is being done while it is being compressed. Now, this is another view of the lobe type and this is the constructional feature you can see in this case lobes are straight here as you can see and you can see these operations. How these operations is being done gradually 1, 2, 3, 4, 5 these are the 5 stage of operations. I think you can study this yourself. Now, next one is the vane type compressor. In vane type compressor this is the principle is exactly same as what is in hydraulic machines oil hydraulic machines. Now, the this is a typical capacity 2.5 meter cube per second this is very high and 0.35 megapascal in single stage. Now, if you look into this this vane are not placed exactly radial you will find that is inclined. This inclination is given is like that for this compressor you will find this is rotating in this directions not in this directions. So, that this is having the sealing effect better sealing effect. If you rotate in this direction the pressurized oil will put the pressure and to allow it to go inside and so, there will be leakage through this. Looking into this vane orientations you can find that this is the direction of that means, from this side it will rotate in the anticlockwise directions. This you can see how much this inclination is there and this is the constructional feature of the vane type compressor. And also if you look into this in this case of course, the vane are straight, but this is on what is that there is a this is shown that how the thrust pin are provided. And then and this is the packing strip this is the rotor and there is the slot veins etcetera. This is a functional feature may be this is also the straight type veins are used. Here also as you find the veins are straight now if you look into the compressor rating. The rating of compressor is usually expressed as its storage flow in flow in rate capacity of free air that is at atmospheric pressure that is 0.101 mega Pascal absolute 14.7 psi and temperature is 20 degree Celsius. The flow rate is then called standard flow rate and usually express in meter cube per second. So, this means that intake volume we call in meter cube per seconds. This that volume what we have the mention in the capacity that is the intake volume to the machine say 2.5 meter cube per second is the intake volume per seconds. Now, this gas law law is known to you. So, we can use this gas law to calculate the rating of the compressors. V P and T are the indicate the volume pressure and temperature respectively and subscript 1 and 2 represent compressors inlet and outlet parameters. Dividing both side by time q we get in terms of the flow rate. Now, if you consider a problem the a typical numerical example in a large scale system the air is used at a rate of 0.0142 meter cube per second at 0.875 mega Pascal and 32.22 degree Celsius. Celsius spelling will be S not C. Anyway, this is now this rate if you look into this rate is the delivery rate utilization rate not the compressors rate. Now, we have to estimate the free air flow capacity of the compressors. In that case the solution is like that in this equations what we put that is the q 2 is given that is the q utilization side that is the outlet of decompression. So, q 2 is this mass and pressure p 2 now this pressure whatever pressure is given here mind it we have to convert it into the absolute that means you add simply the normal absolute pressure. So, and then the temperature is we have to add 273 that is the reference temperature we have to add this and then the this to T 1 and T 2 temperature rise is from 21.11 to 32.22 and what we find the 0.132 meter cube per second of free air we need to compress. So, note absolute temperature is taken as 273 degree Celsius and this means that in order to have an air of 0.875 mega Pascal at 32.22 degree Celsius at a rate of 0.0142 meter cube per second by the reservoir of a compressor it needs a supply of 0.132 meter cube per second at 0.101 mega Pascal and 21.11 degree Celsius. Apart from the storage of air reservoir that is storage tank of a compressor dampen the pressure fluctuation and supply the pressure to utilization ends at constant pressure. In many cases among all pneumatic system at the utilization end a few may demand the higher flow rate at starting which exceeds the capacity of the compressor. A well designed reservoir is capable of handling sub transient situations that means time to time we need more excess air to flow. A reservoir size is expressed now we have to also depending on the plant we have to find out the reservoir size. This is expressed by this formula and where you will find is the time that the reservoir can supply required amount of air and then q r is the consumption rate of the pneumatic system q c is the output flow rate of the compressor and P max is the maximum pressure level in reservoir and P mean minimum pressure level in receiver and V r is the receiver size. So, again we consider another problem calculate the required size of a reservoir for a system consuming 0.1 meter cube per second standard for 6 minutes between a pressure limits 0.7 mega Pascal and 0.56 mega Pascal before the compressor resumes operations. That means this is the maximum limit where the compressor will be stopped and this is the minimum limit when again the compressor will start. What size is required if the compressor has to run and deliver air at point not not 2 meter cube per second standard. Now, simply in this to calculate the V r we consider this is the pressure and this is the 6 minutes time means this is in second and this is the difference of this pressure pressure here and this is the difference in the capacity flow capacity. So, what we find that we need the reservoir capacity of 2.6 meter cube at least, but here we have simplified the problem to arrived into this say formulation this as a requirement is this you have to exercise that really you have to make the average of total utilization compressor time how much it should be stopped etcetera. So, that becomes a little complicated not this simple, but for as a numerical example this is the way how to calculate the capacity of a compressor size of the reservoir. Pressure at numerator and denominator have the same unit that means in this case you should take care that this should be same unit even if the pressure as expressed here in PSI that is not a problem this and this and in case of B as you can see that this is the meter cube per second the standard. So, for that we need 0.208 meter cube suppose this amount of flow as intake is provided then we can reduce the capacity of the reservoir. Generally in selection of a reservoir tank size 50 percent oversize is recommended considering 25 percent for overload and 25 percent for an expansion if needed in future. Say for you are designing a certain compressor and reservoir for an industry then in that case first of all you have to consider at least 25 percent overload may be there. So, 75 percent directly coming over there and usually what happens after setting up you may need to add 1 or 2 more equipment with that. So, another 25 percent that means whatever capacity is wanted for industry usually if it is in the beginning stage and considering that is the 50 percent requirement we usually consider 100 percent and then we design the compressor. Now, power required to drive the compressor a semi empirical formula is usually is used in recommending actual motor size compressor efficiency to be considered. Then this is the semi empirical relation to calculate the power where P this is for the total of the motor and then this is ideal. So, we are calculating the ideal one and then we divided by the efficiency overall efficiency to calculate the power and Q is the flow rate standard and P in is the inlet atmospheric pressure in Pascal's and P out is the outlet pressure in Pascal's and absolute and this is the overall efficiency. And again if we consider another problem determine the motor power required to drive a compressor having overall efficiency is equal to 75 percent that delivering 0.4 not 47 meter cube per second at a pressure of 0.2 mega Pascal's. So, these are the given data considering this we can calculate this power ideal is coming 13.3 kilowatt and the efficiency is 0.75. So, 17.73 so we recommend a motor of 18 kilowatt. I think we can continue these components in the next lectures. So, now this is main portion of this is a book this is available in print is all India Indian book I do not know whether the print is still available or this is available in the market. But, this is very good book to have some basic knowledge about the pneumatics also there is another book that is by India publications and also this is print is all of India, but some practical application the second book is good and for basic knowledge the first one is very good. So, thank you.


Hey, what's going on everyone? I want to thank you so much for tuning in to another episode of just my opinion reviews I really do appreciate it and just like I did last year at the end of 2017 I am doing the exact same thing this year end of 2018 with my best worst and favorite list of 2018 This one right here that you're watching you saw the thumbnail you saw the title This is actually actually I don't even know what my title my thumbnail is going to be So this is it going to be like the top 15 Favorite movies of mine of 2018 you may be sending yourself a brand and why are you doing your top 15? You should do your top 10. Well, you're going to get my top 10 because it's going to be here You're just going to get an extra five as well because there were so many films that I did enjoy this year now I did say best favorite and worst now This is my top favorite films that is different from top best films. What do you mean? This is what I mean my fate top my favorite is my biased opinion It is it is a more subjective approach now all films are subjective meaning that just because I like something You may not and vice versa, you know, and that's perfectly fine So there may be some films on my list that you may not agree with that you disagree with and that's perfectly fine There are also a number of films that I did not see this year So I can't talk about them or put them on my list if I haven't seen them So I have my list of 10 to 15 right here very excited to talk about it And I just want to also just stress this so you understand There is a difference between best and first best is a more objective approach my best list of films that I Feel that should be best picture Contenders because the story was great and it also just had great acting again my subjective opinion It's just going to be films that are just my own biased opinion. I don't care about plot I don't care about story and things like that. I just had a ton of fun with it That's what it means on the surface But for me personally I do care about plot and I do care about Story and acting and the fix and all that I'm not just gonna be putting on here a bunch of guilty pleasures No, these films on my favorite list are at the very least an 8.5 out of 10 and higher But these are just list of films that I can just they're my favorite I can watch over and over and over again if there is a plot point or anything like that That just doesn't make sense. I really don't care. I just have fun with it You know, so it is it is a it is an objective approach as well But the subjectivity comes before anything else So I know for all that rambling let's go ahead and get to my number 15 favorite film of 2018 and that is also a surprise for me and that is instant family It came out November 16th. It is a comma Consec comma a comedy drama. It was a written and directed by mr. Sean Anders I'm a decent fan of his I don't know too much. He did a sex drive daddy's homes two and one That's my boy. This film right here is loosely based on a true story that had to deal with him the director Sean Anders and It stars Mark Wahlberg and Rose Byrne and what it's about is just a couple found themselves You know not they haven't had any kids and they want to adopt foster kids and this is not just a comedy There had a lot of heart to it It was a lot of realness to it. It was a lot of things that I just thought of I did not expect He has some pretty good performances, too. It's a favorite of mine. I don't know I mean I may buy it or something like that, but it is something that I can watch Over and over again coming in at number 14 is a film that I think a lot of people just forgot about it came out January of this year January 12th, and that is Paddington, too I love this bear so much is this a cute cuddly bear on the surface. It looks like okay I would not be interested in this film at all. This looks childish. No, I mean they have childish jokes But at the same time they do have a lot of adult themes as well. I think the effects with the bear Paddington is phenomenal. It really looks like a real bear on screen photo realistic CGI The writing director is Paul King and it's just a it's just a great film You know just about a bear trying to live his life in England and you know be loved by family I recommend it. I love the first Paddington and I love Paddington too. All right guys coming in at number 13 Is a film that I just recently reviewed and that is if Bilstry could talk written and directed by a brother Barry Jenkins, I love this film right here. Also, let me go ahead and say this guys There may be also films that are on my top favorite list of 2018 that are also on my best list of 2018 So I just wanted to make sure that you were aware of that but coming in at number 13 is if Bilstry could talk I said in my review and you can go check it out. This film right here is a textbook example of black love It's a type of love story that I have never seen before While simultaneously being infused With weight racism and white supremacy and things that you know took place in the 70s I love this film. I thought the soundtrack was fire I will be buying this film when it comes out on Blu-ray 4k and all that good stuff I love the love of the couple. I love the love of the family I just love the whole film and I strongly strongly Strongly recommended and think you all think all you guys to take a chance and go check it out And that is number 13 if Bilstry could talk now coming in at number 12 Is a film that I don't think anybody is gonna have on their list But I put it on mine because I had a lot of fun with it and everybody crapped on they sent it It was a bloody joke and it was stupid and it was this and it was that and it was just comical But I had a great time and that is Shane Black's predator movie that came out this year I think I gave this film like a 9 or 9.5. I don't understand why I mean it is a silly movie It is a goofy movie, but at the same time, I feel that they did take it seriously as well I thoroughly enjoyed it. I really I haven't seen predator 2 and a lot of people saying I need to go see that I don't know why I just said that it didn't have really thing to do with this movie But the predator film was a lot of fun. I mean, it was a great action film I like the story of it. Like I said, it has some goofy and silly elements But that's okay because I'm a goofy and silly guy and I just had fun with it So predator that is coming in at number 12 All right coming in at number 11 on my top favorite list of 2018 is a film About a toddler of a quiet place. I love this film.  I don't think I'm gonna be interested how in the world Are you gonna have a Suspense for movie when no one can talk. Well, I was wrong and I'm glad I was wrong because this film was amazing The director is John Kretzinski The another actress in this film is Emily Blunt who plays They are married and it's just a great film a lot of people talk about how they want them to to be Mr. And Mrs. Fantastic and the Fantastic Four. I would love that But this is a supposed apocalyptic world where a family is forced just to live in silence or they will be tough eaten by monsters and It's just them just trying to survive and all the weird Contraptions and the vices they have to come up with so they can make it through each day It's very clever. It's very thought-out very provoking. It's a super mystery thriller. I loved it This is something that you really want to see in the theaters If you can I remember you can hear a pin drop when I was in the movie theater No one wanted to talk and that's just a type of audience engagement that I love to be a part of This is a fun film. It's something that I can watch over and over and over again I loved it. I didn't buy it yet, but I will be buying it You know, I I do have a budget like everybody else. I can't just buy everything, you know I'm saying if it's come a book movie, you know, I probably can't but I really did enjoy this movie I think you will too. So that is why a Quality place comes in at number 11. All right now guys We are now in the top 10 see I told you don't get my top team This is my top 10 favorite films of 2018. I remember this snuck up on me I didn't even know about it. It was a I think it was I think it was on my subscriber Cheryl I think if it were if it were from mom, please forgive me But I think it was you Cheryl that recommended to this film Or you told me to react to this in like another video I was like, okay, what is upgrade and then I saw the chair and I was like, oh snap This is all the goddamn chain.  I love that and this film upgrade Had all of that it's written directed by label now They carry my earlier this year June 1st of 2018 and when they have all these martial arts elements and things like that They mix it in was like future cybernetic technology Artificial intelligence AI and all that good stuff and it was phenomenal the ending was almost disappointing to me But I liked it. They had a nice sense of heart and touch Towards the end especially like with the mother of the main Protagonist in this film. It was nice. I don't even think it was that long. It was like yeah I were 40 minutes. It was just great hand-to-hand action great direction by the director And Logan Marsha Green who called people call him the broke Tom Hardy. He's a great actor to me I liked him in the I like no, I didn't like that movie, but I liked him in The alien covenant movie, but it's just a great film I loved it great story kind of something that I've never seen before and I will be buying this too When I get some more money All right guys coming in at number nine is a headbanger man when I saw this in a theater I was jamming this group is fantastic and I don't even know much about them, but that is Bohemia and Ramsey Now there was a lot of controversy with this film because you know people hold it's based on Queen the band Queen that was doing her thing in like the night the 1980s They had one of the best performances live concert performances of all time at live eight in 1985 And one of the countries in Africa. I can't remember exactly I said controversy because Brian Singer was Directedness, but then you know he had it was reported that He was sick. Well, not he was sick, but family member was sick So he wasn't showing up to sit so he was fired or whatever I don't know and somebody else came in But it's loosely based on a true story of Queen the controversy also comes because a lot of people say it's not 100% true But besides how that I enjoyed it Remy Malik Played of Freddie Mercury and I think the performance is great one of the better performances of this year He really did give all he could to that role in his show on screen. I was jamming my head in theater I loved all the music. I was a big fan We are the champions in the 90s when I was growing up and that song was introduced to me, too You know in the mighty ducks franchise. I love that franchise. It still holds a special place in my heart So especially when they played that song and this thing I was just like we Y'all I know I could say now I'm just I am just joking but not this film was a lot of fun It was a great story great acting great storytelling great performances. I really didn't enjoy this I remember my mom's just like yeah, I'm not gonna see that. I was like no mom you need to see this movie. It's fantastic I loved it. So that is why Bohemia in the Rhapsody is coming in at Number nine. All right guys coming in at number eight and Yeah, none of the look at it. Oh, I put no sir. I do want to switch this order Coming in at number eight Is a film that I mean I was gonna say these films just keep getting better and better, but that's not necessarily true But it's still a great film and that is mission impossible Fallout right where we get right? Excuse me. There we go right there got that film right there on a Blu-ray 4k actually got this for a Christmas gift So you can possibly tell when I'm shooting this right here, but I have mission impossible fallout right here It was the written and directed. No, it wasn't written, but it was directed by Christopher McCurry He's also the gentleman that directed the last mission of possible film and But mission impossible one two three four five I mean they just keep getting better and better and better and then you know mission impossible five and six kind of Kind of plateau for me, but I still enjoy the hell out of them this out of them This film right here was actually shot with IMAX cameras So when you're watching it some of the action scenes When they have when you're watching at home and they have the black bars at the bottom of the top of the screen When the IMAX scenes come those disappear and the screen expands and it is it is really a nice experience at home And while you watch it in the theater, but these films right here.  But Tom Cruise and his team being rames and everybody they always come through and save the day and save the world And this is why they're entertaining. It is a fun ride I really don't want them to stop making these films because they're just great and they make money and they're good So I mean I love these films and that is why mission impossible fallout comes in at number eight alright guys Coming in at number seven on my top favorite films of 2018 it was a film written directed by mr. Steven Spielberg one of the greatest filmmakers of all time and that is a ready player one Man, if this was filmed in IMAX, this probably would have been one of the best movies I've seen forever But oh my goodness gracious guys the pop culture references in this film was this freaking stellar phenomenon I mean like this is a true dream come true for any geek of Anything in the past 30 to 50 years I mean they threw every Easter egg imaginable in this film and not only that it just looks beautiful the Offincer to score with the music was good in this but the effects in this thing were just like top-notch I mean they really got every digital artist They possibly could on the planet and put them together to make a beautiful film the story was great I love the characters everything this was just a fun movie something that I can wash over and over and over again And especially at the end when he did that how do I can y'all know what I'm talking about if you're a friend of their franchise But this is a great film. I loved it and I think he will too Ready player one blu-ray 4k right there, baby number seven top top 10 Favorite of 2018 Alright, we are moving Quite along now Coming in at number six. I do not have this film Ready to show you because it is still in theaters right now and that is spider-man into the spider-verse it was directed by a pop hero Shady Peter Ramsey and Rodney Rothman and It's a great film guys. We have Mars Morales. Of course, I can relate to this a young brother He's black and Hispanic of course I can't relate to the Hispanic side But I can relate to the black horse sign and just the way he was just singing in the trailer I don't know the words and he didn't even in the movie You know like we all do that sometime You know I'm saying and just without them just like black black black black black black which is nothing wrong with that Anyway, I was really able to relate to him and you can just see like just little nods Easter eggs of this random Mannerism throughout the whole film that I can just relate to besides that I'm a big fan of spider-man Okay, so we got spider-man and this to a perspective we've never seen before and multiple spider-man's I mean how can you lose with that? You really just can't the effects that Sony put out her right now that they're trying to actually patent that technology And it was a great technology I can't get mad at them for that those effects and things like that is something I've never seen before the way the film Broke the fourth wall and like, you know at one point I'm never throw something hit them in the head and like the captions that were like pop out like This is a food or a donut or something just randomly when they talked of the Decommon book bubbles will pop out. I mean it was just something I've never seen before. I love this film I cannot wait so I can buy this on blu-ray 4k I know it's gonna look beautiful on my display when I get it at home But you know, it was just a great film. I loved it and that is spider-man into the spider-verse coming in at Number six. Okay guys, well now we are in the last five the top my top five favorite films of 2018 and Coming in at number five is a film that I was actually late to the party Everybody got to see this before I did but that's okay because I was actually able to pay to see this film I was able actually to contribute to the box office and give them my dollars But let me pull this up real quick. I should have had it ready But you know hey sometime I just be freestyling just I want to give you all the info I possibly can but this film right here coming in at number five is Written is directed by mr. George Tillman, Jr. Believe it or not. It's a black guy and he directed soulful men of honor and notorious. I loved all those film I'm saying that I did not know if it was named Prior to this. I mean I should have been paying more attention But like I said, that is the hate you give I have I don't own it because I don't I think it may be still at The dollar theater right now and came out on blu-ray. I ain't bought it Oh my gosh this film right here was super duper serious a mandala Steinberg she fantastic actor actress Excuse me as the main protagonist of this film of course this deals with racism and white supremacy I love this film to death. It spoke to me on so many different ways because With the good and the bad it was so realistic to me because I mean I love everybody for the most part You know I'm saying, you know even in my community Of course But even in my community you have some people that I still just cannot stand and of course I cannot stand the races and that this film dealt with both sides You know I'm saying I mean even though people that you love just do things that you just cannot stand and I don't I know I'm being extremely vague. Go check out my review for this film I don't I don't want to review this film right here, but this was Given the climate that we're living in right now the political climate this this film right here just speaks volumes it is a true eye-opener and Just I like how they compressed all of these themes and elements of like racism white supremacy and Justice and all that into one film one two-hour film to really paint the picture of Black people's plight and people of colors plight and things that they have to go through There was a ton of African-American DOS in this film just descendants of slaves Except for the necessarily the main actress and I talked about that more my my review, but I love to see him I support it Regina Hall did a great job Anthony Mackie Russell Hornsby did a great job Common I mean this film had a fantastic cast and everybody did a phenomenal job It is doing horrible at the box office right now It's only made 32 million dollars worldwide with a 23 million dollar budget So guys without even doing the math is blatantly obvious that this film lost money and that frustrates me So please support the film now if you can You know, I want George Tim and to get work and he's not gonna get work if his films are losing money But let's try to keep it positive, you know, even though I didn't myself But that's why this film right here. The hate you give is coming in at number five Please go check out my review for this film Coming in at number four and my top 10 most favorite films of 2018 We got it right here and that is Incredibles 2 right here Blu-ray 4k, baby Man, it was 15 years that we had to wait on the sequel and it was a I'm glad that we finally got it It was well worth the wait, please don't make us wait that long for an Incredibles part 3 But I don't mean I don't understand why so someone the first one made money and it was a critical I mean, I understand why that, you know Brad Bird the director he wanted to do other things But I think I like the Incredibles 2 even more than the first film and I love that film I mean, it was it was fantastic. I mean the this this is for kids. This is for adults This is for everybody. I really don't understand how anyone cannot like this film I mean all films are subjective. I'm just saying and I'm pretty sure everybody's not gonna be in love with it But I did only thing that I did I like more in the first film was the villain But everything else in this film I think surpassed the first one with the effects the action the comedy just the the relationship between the family and the way They got along. I love how they bicker and argue in the family. It's just a great film I really did enjoy that and that is why the Incredibles 2 is coming in at number four on my top ten favorite of 2018 All right guys, so we are down to the final three final three films of 2018 and I bet some of y'all like Brandon or why haven't you listed this film?  All right guys coming in at number three I don't have it on blu-ray 4k right now because it is still in theaters But I love the first film and I love this sec the sequel even more and it is Creed 2 baby. Yes, Creed 2 Starring mr. Michael B. Jordan. Mr. Eric Killmonger. Mr. Mr. Creed I said mr. Creed. I love this film, you know, we got Sylvester Stallone coming back as Rocky, of course This is was not directed by Brian Brian Ryan Coogler This is being directed by steeple Steven Caple Jr. And he did a fantastic job Like I said, I think I like Creed 2 better than the first one and I love Creed 1 But the training months Hodges in this thing like when at the end when he was in the desert super fire the Ivan Drago Not Ivan Drago his Ivan Drago is doff lung ring. What was his son's name? I forgot I got it. What was it? Where is it at? Where is it at? I got a Victor Drago played by Florine Florian Monteney Monteney if I'm pronouncing that wrong, I'm I'm pretty sure I am but it was freaking fantastic. You got Russell Horne's being this thing as well I really did feel I mean and the fight in the middle I didn't know how I mean some of this stuff was predictable, but some of it wasn't I really did not know how I was going to end I like everything with Tessa Thompson and her relationship And you know with the baby and things like that. I like the argument between Michael B. Jordan Sylvester Stallone I like Felicia Versailles, you know, but mama chicken her son. I love so much in this film right here Please go check it out. I definitely will be bonus.   But like seriously like real talk But creep to I love this film my review for it is up on the channel. Please go take please go check it out It is a phenomenal film. All right guys We're down to the final two films of 2018 that are my favorite and coming in at number two Is blacks clansman, baby. I got it right there on blu-ray. I know I just didn't feel like buying us on full k I didn't see the the need to but man hold up this film right here is written and directed by By spike lee. It's a spike lee joint. Uh producer of this was also Jordan peel who did get out and is doing us right now I believe Jordan peel. He just I don't think he just wasn't associated an executive producer I think he was like a producer producer to where he had a lot of creative control and decision making power I'm so glad that he cast John David Washington in this film. Um, Denzel watched his son I love this film right here. The part where they were talking about double consciousness spoke to me The speech at the very beginning uh, were corrie hawkham Was I forgot the gentleman he was playing. I really I I forgot my I'm so sorry guys Uh, but the those floating heads that really spoke to me everything in this film spoke to me I love this film. I got it right here. I can I don't know why says about three times already at home after I watched this thing Only thing that well the movie is great.  This is it comes in at number two for my top Number two favorite film of 2018 All right guys, we are down to what the final word my favorite film of 2018 Um, some of you guys probably already know what it is. Um, it may Create some controversy some division. I don't really care I'm a little exaggerating when I say that right there But to be honest with the guys, uh, I couldn't make a decision on number one. So there's a tie Okay, I still cannot decide. I'm looking at them both right now. I still cannot decide Which film I like more. I mean Gosh It's just too difficult for me. I've tried. I've been back and forth. I still to this day. I cannot determine which one I like more Um It's just too hard. So, uh, it is a tie Come so coming in and just two films. I'm gonna listen if you don't like me tying them. Hey get over it but uh, the first one is, uh Marvel's The Avengers Infinity War, I don't know. I'm holding it right here now and I forgot the title of the film That is number one. Uh, well part one of this and coming in, uh, and number one again the tie Of course, it's Black Panther, baby And I got it right there on blu-ray 4k and I also have an on, uh, 3d Um, if you have a 3d television, they don't sell this in the states You have to order a lot overseas But if you have a 3d television, I'll strongly suggest you buy this in 3d because They had the i max ratio for this film is on this on the 3d disc And you don't have to watch it in 3d. You can still watch it in 2d if you have a 3d film to see the i max ratio If you don't have a 3d tv and you still want to watch the i max ratio Um, it won't work on your tv But there is a way that you can convert the file convert the disc and put it on a blank blu-ray to watch it I've done it myself and it's freaking amazing But we got Black Panther and we got Avengers infinity war right here Uh, two of my favorite films of all of 2018. Of course Black Panther. I mean come on It's a comp these are comic book films.  I really don't I'll just call him the antagonist. Okay, because I really don't even feel the film was villainizing him They really get they gave him a valid reason to be upset I just did not necessarily agree with his handling of the situation Only things I didn't agree with killer monger was killing children And going on the offensive. There's only everything else, bro I'm with you right there. You know I'm saying black liberation. Oh, this is bullcrap. I I feel you my brother.  I'm gonna go and bust on tears right now Um, but yeah, you know, I don't agree with killing children. I don't agree with uh going on the offensive I'm a strong advocate of self-defense Uh, I mean the costumes in the film were just like top notch the song the soundtrack, you know the acting the performances Was stellar, you know, I I could nitpick the film, but we're not going to do that right now And then when you get to Avengers infinity war Thanos, I mean one of the baddest villains Uh, yeah, he is he wants to murder the whole universe Uh, but the performance was great. The effects was great. Uh, I mean, I love everything about it I remember geeking in the movie theater when I saw this in iMacs Doing some of the action scenes all throughout this like, oh my god You know going like that. I mean, these are my favorite films of this year I can watch both these over and over and over again This is like this this nearly met all of my expectations and so did Avengers infinity war It was such a build-up to those films right there and it was just phenomenal. I love them all But um, yeah guys, that is my uh, that's my list for 2018. I hope you enjoyed it So let's recap real quick coming in at number 15 is uh, instant family coming in number 14 is pataton 2 13 is if bill street could talk 12 is predator 11 is the quiet place 10 is upgrade number 9 is bohemian rhapsody number 8 is mission impossible Fallout number 7 is ready player 1 number 6 is spiderman into the spider verse Uh, number 5 is the hate you give number 4 is the Incredibles number 3 is Cree 2 number 2 is black clansman and top for number 1 for my favorite films of 2018 is avengers infinity war in black panther Well guys, I hope you enjoyed it. That is just my opinion for my top 10 top 15 favorite films of 2018 again Guys, this is not my best. I will be making a top 10 best and it is going to be top 10 top 10 best Films of 2018 when any of the films that are on this list pop up on that list as well You're just going to have to stay tuned and find out because I'm shooting that video right after I'm done shooting this one As well as my top 10 worst of 2018. So thanks for tuning in guys, uh, please Oh, no, um, so that's just my opinion Um, you know, what did you think? Have you seen any of these films? Have you not seen them? Do you want to see them? Have I turned you all in? Have I turned you off? Do you agree with me or do you disagree with me? Let me know down in the comment section below Let's get this conversation going and keep it flowing If you like this video go ahead and give me the thumbs up if you dump this fine But you can still subscribe to my channel You can also look me up on social media facebook instagram and twitter all that good stuff It's right there at the bottom of the screen and I made it very easy By providing links to all that good stuff down in the description box below But guys, I just want to thank you again for tuning in to my opinion slash review Of my alarm going off at the end of this video and before you go.


Good morning, everyone, do we all have enough coffee? Maybe? OK. So I'm here to talk about my first year at Chef, measuring all the things. I've been at Chef just over a year now. And a bunch of people ask why I came to Chef and what brought me to Chef and what I used to do. So I'll start by talking about that a little bit. So who am I? Why am I there? I started out doing a little bit of software development for a hot minute at IBM. I was a software engineer. And then I did hardware. And along the way, I ended up supporting those systems a lot of the time. So that was my background. And then I went and got a PhD. And right now when I'm at Chef, I spend a lot of time helping the company out internally. I ended up consulting them, helping them out, kind of figure out how to measure what they're doing. Sometimes I help our customers measure what they're doing. But essentially, I end up helping us all figure out how to make things better. And especially helping us make things better with metrics. Because we can't improve what we don't measure. So the joke is that I rub science on things to make your dev and your IT ops. And your dev ops better with metrics. So who in here is on the dev side of the house? Who in here is on the ops side of the house? Awesome. Who's security? Okay, so we've got a handful of security. Who's like QA test? And who's here just for the free food? Fantastic. Okay. Who's here for some food? Coffee. Awesome. So as we start moving forward in our journey, metrics really help us make better decisions. And it's finally starting to move into the IT side of things. For years, business has known this, right? We all have metrics around sales, right? We all have heard metrics around sales and revenue and ARR and TCB and like whole bunches of three letter acronyms that people all throw at us. But when it came to software, we all just sort of guessed or had intuition or tried to figure things out. So now we're starting to do this around software. So what did I do at Chef? What have I done when I work with companies in this area? And how can you do it too? So otherwise known as a talk outline. Where do you start? What sort of numbers should you think about? What about benchmarking? And what are some other things that you can think about as well? So where did I start? First of all, you can start at the highest level. So for this, think about what makes sense for you. So for me at Chef, they asked me to take a look at the entire level of Chef. So I started by talking to some of the executives, several of the executives. For you, if you wanna do this for your very own team or at an individual level, start talking at your team. If you wanna do this for your team, start talking to middle management. Ask around, ask what's important. What matters to you? What matters to your team? Is measurement happening? Is metrics even a thing? Ask around. Next up. But all we do is fight. Or I mean, talking circles. One thing that people always forget about or they don't necessarily realize is that metrics provides an opportunity for communication. I'm sure that several of us here have heard of CAMS. Have we heard of CAMS? CAMS is a thing, right? When we talk about DevOps, we know it's communication, automation, metrics, sharing. The really great thing about metrics is that it actually helps us communicate because now we can start sharing what it is that we're doing. So metrics really help us long here. If you still aren't sure, ask what's important. This can be done at any level of the organization. So ask your team members. At Chef, I started by laying some groundwork. I shared this really, really great O'Reilly short book. It's free, it's all online. It was written by Hilary Mason and DJ Patil. Since they wrote it, DJ Patil was named as the White House Data Scientist, Chief Data Scientist for the US. It's about 20 pages. So I just sent out an email introducing myself to the company. I attached this, I said, feel free to read it if you'd like to be, you know, if you're interested, if you'd like to take a look and see what I'll be doing here at Chef. And I just let them know it's about 20 pages. So quick, quick read. I also established the Chef Scorecard. So this was something that came from my conversations with executives. Asking them what was interesting, what was important to them, what were their goals for the year. So we called it Scorecard because goals and initiatives was like a special word for executives, right? Because words have meaning, right? Definitions matter. So goals was a special word for them. So I called it Scorecard. Now the rule here, this was important milestones for the whole business. It had to fit on one page. No cheating on font size. I used to be a professor, right? So I was like, I had to hold myself to the same rule. No, like six point font. I think I kept it to 11 point font and one more margins. Because then if I needed to, I could print it out on a single page and anyone could keep this near their desk. The important thing here is that by keeping every important milestone or goal on a single piece of paper, anyone else in the company could figure out if what they were doing that day was important to somewhere in the business. Could my work today map to something that was important to somewhere in the business? It may even be important to map to a few areas in the business. And this was important. At first a few people panicked, right? Because it might take a little bit of thinking to figure out where it is that what you do maps. So this is scrubbed, but this is the 2015 scorecard. So you can see how ecosystem training and community. Now some of these things might be difficult to measure. Totally fine. That doesn't mean they aren't worth measuring. Some things we decided to come around to, we'll figure out how to measure them later. These are things that are important. It was even interesting. So one example here, international infrastructure, it came from our VP of legal. I was asking her what was important and she actually made a comment and said, wow, thank you. No one's asked me this before. She's a VP. So even just asking everyone what's important to them at the appropriate level can be huge. Examples from financial, marketing, people. So that's our HR team, sales and BD, product and engineering. So I was able to collect all of these. Now, once we had all of these, what we wanted to do was collect them and measure them periodically. This was the goal. So what we wanna do for each of these is define them once you have whatever metrics that you have. So again, each area was going to be responsible for their own. Define it so you know what it is you're talking about. Set a target. This target may change and then measure it periodically and then communicate it throughout your team, your organization, whichever the appropriate level is. You have a metric, you have a baseline. You know where you are currently and you know your target. So you can see how you're progressing. Now, keep in mind, your metrics aren't set in stone. A handful of those, so that scorecard was our initial scorecard. A handful of those metrics ended up getting tossed because there were a few things that some of the executives that were super important, absolutely loved, after a few months or a few rounds, either I'm not, they were no longer super passionate about it or they realized that it wasn't driving the things that they thought that they were driving, which is fine. Another thing, you can start with an MVP, that minimum viable product and then you can iterate. Also, as I just mentioned, toss what doesn't work. This is a continual improvement process, right?  The next big challenge. What numbers should I think about? Business has set metrics that they use. We've been doing accounting for years and decades. So I also have a master's in accounting. I've used like money numbers for examples because we know them, right? We've been doing accounting for decades. There's a reason those numbers don't change is because we've tried them for years. Software is different. We're just starting to figure out how to build software and how to build software in different ways. So what numbers should we be thinking about? There are three general categories here. So any time you start on your journey, try to think about at least three general categories. If you're just barely starting on this, pick one or two in each category. The first one is going to be external. Outfacing customer focused. Now, when I say outward facing, customer focused, think of who your customer is. Your customer might be in your company. So who is it that you support? Think of one or two metrics here. It can be subjective. That's gonna be like my next objective versus subjective. So subjective is something that comes from like a survey. Someone's opinion. Could be customer satisfaction, even if it's your internal customers. It could be objective. It could be something that comes from log files, okay? Internal, so you're inward facing your process improvement. How do your inward, how do your own systems behave? And then culture, because people matter. Go back to your most important things list and pick something on that list. It can include things like maintain excellent customer satisfaction, increase the speed of software delivery, hit your revenue targets, increase software quality or usefulness. This is going to be your external measure. Okay, how does this apply to us? It gives insight into your metrics that are important to areas. It identifies potential external metrics and it's going to focus your efforts on value added metrics. At Chef, we started with an engineering initiative. So start by identifying a goal. So I flew through that Chef scorecard earlier. We started with Chef every day. We wanted to be able to ship every day. So ask yourself, is there existing data? Is there anything I can reference right now? Took a look at the data when I first got in there. We didn't have consistent sources of objective data. So that objective data comes from our system. We had some data. It wasn't totally consistent. It wasn't super awesome. We took a look at some of our third party data. We were using third party tools. Dug into some of that. Not super awesome. So what we ended up doing for initial steps. Remember that slide I had with a star just a minute ago where I said, MVP, iterate and improve? So what we did is we started by doing some subjective data collection. We went around to every team. We went around to every team lead and we said, so starting with test maturity. We know that test maturity is going to be an important part of delivering code for people here who are devs. Does this sound right? Does this feel right? Awesome. So what we did is we said, before we start building out this massive tool, which is gonna take a whole bunch of time, we're just gonna go interview all the team leads on a periodic basis and say, do you have all of these tests done? Have they been done?  Have they been done? We did this as a gut check. Interviews were conducted monthly with team leads on each product and we calculated the percentage complete for each area calculated and communicated. How hard is this gonna be to do for anyone in here if you don't have any data yet? Or if you realize that your data isn't very good. Can we do this? We can all pull this off, right? Okay, here's what we found. Oh, and these are, by the way, some of the example questions for integration tests. So we pulled together questions, pulled together the team. This accomplishes a few things, by the way. This socializes everyone to the idea of metrics. This gets buy-in for everyone. This gives everyone exposure, feedback. We did this for several different areas for unit component integration, upgrade compatibility, ancillary. We ended up adding a few more areas. The other thing that lets us do is it lets us test which ones we think are most important so that when we start asking for support and resources to build in tooling, we can have a pretty good idea of which ones we think are most important. So if I wanna come in and tell them we need metrics for automation and tooling and we need metrics for all of this stuff, build this, how much excitement do you think I'm gonna have for people who are like, no, I'm super busy? But if I socialize this and I get data, this is what we had. Here are our initial charts just for the first couple of months. Not necessarily super awesome. This has been scrubbed because these are charts for all test maturity. So this is a composite score across each product or feature, so you will not notice product or feature names at the bottom, but it exists on the internal charts. So by the way, this is real data. This is old data though. This is also super old data. So we now have charts that cover lots and lots of stuff. Here's where it's interesting though. So what about benchmarking? I'll come back to these charts. A benchmark is absolutely essential. What you have to have, you have to have truth. Even a bad baseline is good. Because it tells you where you are and it tells you where you can improve. So one thing that was awesome here is that those charts are honest and they are true. And that's why I'm showing you super, super early is because the team was super awesome and they acknowledged the fact that they had improvements to make. You need to have at least one reference group. You have to have something to compare. So I'm showing you month two. Month one is good. You have somewhere to start and then you have something to compare to. You can compare yourself, you can compare to yourself, back. Like back at time period. You can compare to someone else. You can compare to another team. You can compare across the industry. You can compare somewhere else. You also need to make sure that it is communicated and visible either to your whole team, to other teams, to the company. So let's compare, okay? So let's run through that checklist I just had. Charts for all test maturity for each product and feature. Does it have truth? At least relative truth. The teams were committed to being honest. It was communicated and visible. This was shared to a Google Drive that they actually reminded all of engineering to take a look. It was also like if anyone in the company wanted to take a look, you totally could. There is at least one reference group and even a bad baseline is good. Like they went ahead and pointed out, like they just went ahead and let that product feature. Now this was actually a pretty new product and feature. I will point out or notice that there are a few areas where month two goes down. It's because they introduced, they realized after the first month that they were missing an area of test they wanted to add. So instead of like recalculating and renormalizing, they just went ahead and said, we'll take the hit. We all know what this means. We're fine with it. Again, your metrics aren't set in stone, right? They went ahead, they added a whole new test area even though they realized it would mean that their charts would look like it went down because it looked like they were missing a whole area. Start with an MVP, iterate and improve. We're now building in metrics for automated data collection. They started with interviews because they wanted to get a handle. They wanted a better understanding systematically of what was happening. TOSFIT doesn't work. So we talked about external metrics, right?  That was our external metric. The internal metric is test maturity. Also wanted to tie to cultural metrics. So I am a big fan of the Westrom organizational cultural metric. There are teams now in Chef that have started capturing this on a quarterly basis. Organizational culture we know is important. This measure in particular actually comes from the work of Ron Westrom. He is a sociologist who used to study healthcare and aviation, which some people say like, why does that relate to IT at all? It's because healthcare and aviation are highly complex systems. And this organizational typology predicts what happens when things go wrong in highly complex systems with high risk. Would anyone here agree that IT is a highly complex adaptive system? Do things ever go wrong? Maybe. So this is awesome because the thing that it optimizes for or the thing that's really important is information flow and trust. So who here has a friend? That works in a pathological organization. Low cooperation, messengers are shot. Responsibilities are shirked. Bridging is discouraged, bridging across teams. Failure leads to scape coding and novelty is crushed. Within the bureaucratic culture, you have modest cooperation, messengers are neglected. Narrow responsibilities, bridging is tolerated. If there's a failure, it leads to justice. And novelty leads to problems. Now in a generative culture, this is performance oriented. And high trust, you have high cooperation. Messengers are trained. Risks are shared. Bridging is encouraged. Failure leads to inquiry and novelty is implemented. Now, this is particularly awesome. The Western culture is predictive of both IT performance and organizational performance. And across, I'm lead investigator on the state of DevOps studies for the last three years. And overall, we tend to see for high, across the whole population, about half of people end up in bureaucratic cultures. A third in generative cultures to about 15% in pathological cultures. But the high performers are most strongly represented in generative cultures. And by the way, this is a great way to measure it. I know people always say that people lie on surveys. But you can't really get a perception of what it feels like to work on a team from an HR database. You just can't. These are scientifically valid, statistically valid, statistically reliable. You can ask people a six quick question item. And then what you can do, strongly agree seven to strongly disagree, sorry, disagree one, that would be strongly disagree. You can then average up their scores. Four is neutral to come up with like one measure for them. And you can get someone's basically culture temperature, right, you can get their temperature for what their culture is. And this ends up being a leading indicator. Once culture falls apart, technology and tooling starts falling apart six months out. So, summary of that engineering initiative. They collected three types of metrics. External was shipping every day, among a few others. The internal metrics, test maturity in all of those sub-components. The cultural measure was Western culture. They did benchmark the metrics. A few things to consider, subjective versus objective. So they started with subjective and are now moving into objective. Leading versus lagging. So, lagging, most metrics are lagging metrics. We didn't chat about that quite yet. So, lagging metrics tell you about things that have already happened. Leading metrics tell you about things that are about to happen. So, Westroom is both leading and lagging because it tells you how things feel and how they have been feeling, but it also is an indicator for how things are about to go. By the way, one thing to consider is whip limits. So, Domenica DeGrandis is here, and she'll tell you that whip limits are a fantastic leading indicator. Because if you don't implement whip limits, that's kind of a leading indicator for how your software delivery and especially your lead time and your cycle time is about to kind of blow up. So, whip limits are a particularly good indicator for that in technical work. So, another example at Chef. Some of our external customers. So, the goal was increased commercial adoption. Our existing data, some of our existing data wasn't really consistent. Premium features were being reported just as account. We just had a summary count, which wasn't really nuanced. We didn't really have good holistic data here. But our account managers and our success engineers knew that more holistic data would be more meaningful. They were having really great conversations about how you can use Chef and how there were other things happening in organizations that could really talk about your DevOps journey. So, we started collecting more data. We had several key areas for a more holistic approach. What we did is we were walking, they started walking customers through an assessment that had several steps. And we could create then what we call a dojo, the DevOps journey assessment. And we could present them with a chart. And the great thing here, remember I said metrics is also about communication? Before we had a count, and it was visible only inside the company. Now we have a DevOps journey assessment that we also share with the customers. So now we communicate it internal the company and external to the company. So these are two different customers. The second one is what the one I'll use for our benchmarking. It has truth. It's communicated and visible to the customers. We have a reference group. Here the interesting thing is that the reference group is current, it's where they are now, and it's future. It's their goal six months from now. It's where they want to be. So they set a goal and they decide where they want to be. And also even a bad baseline is good. They decide where they are, they decide where they want to be. Now, remember this is also about continuous improvement and iteration. I stepped back in, so I am not the only one measuring all the things. I hope that has been clear. This is totally, I'm only one person, and this is totally a company-wide effort. I stepped in and I took a look at dojo. It's a fantastic effort, but there was a lot of potential for bias there. So I stepped in, took a look, iterate and improve. I took the opportunity to expand dojo in a few ways and decreased the opportunity for bias. And what that meant was expanding a few ways, expanding categories so that there was less overlap in some of the data collection and changed the way we collect the data. And so now we have dojo v2, DevOps journey assessment version two, which is still communicated and visible to customers. We still collect even bad baselines, but now we have a few extra things. Now we explicitly capture organizational culture. It's not rolled into other measures because we know that it's so important. We have technical practices and version control broken out explicitly. We include metrics and decision-making. We have a few extra things in there. So we're continually improving. We're continually iterating with the teams. And again, we still have at least a reference group. It's current and it's goal. We also have previous ones, so we can see them and we can help them see their journey as they go through. So other things to think about. This is advanced topics as we run through for the stats heads in the room. Any, like, no, we're gonna race then. Okay, measurement targets are distributions of probable outcomes. Variance of metrics are thought to influence things. Don't ignore rate of change in your data. By the way, if anyone ever makes distributions or graphs or whatever, if it makes a drastic change, take a look. Super interesting. If anyone tells you to normalize your data, have you guys ever heard anyone say that? Normalize your data. Sure, go ahead, but be super careful because a bad thing is still a bad thing. A customer is still gonna feel like a defect or an escape or a system failure. Don't normalize the bad things. This one is super huge. Everyone, please pay attention to this one. This picture's gonna be really weird because I'm standing funny. Distributions and operations in development are never normal. So we've all seen the bell curve. Bell curve, right? We know the bell curve. So don't report an average or a mean. Especially don't report a standard deviation. It's meaningless. All of our distributions, like this is a normal curve, our distributions look like this, which means that the average doesn't tell us anything. Use a median. That's our takeaway for today. If you're gonna use a number, use a median almost every single time. Especially for our system and our log data. It's almost always going to be a median. And that's it for today. Okay, so the question is that I have three categories of measures, internal, external, cultural, and is there anything that passes between the two? Like the test metrics, I have four ways, but I'm not sure I understand the rest of the question. Oh yeah, so we totally game the system just by adding more tests. Is that what you're getting at? Like we wanna make sure there are good tests. So the thing there, so one thing, if you're only incentivizing people by one metric, you know which metric will be gamed. So you wanna have a handful of metrics. What you wanna do is make sure that you have a handful of metrics that you think are going to impact that outcome measure. But you wanna try to do it as cleanly as possible. So throw the ones in that you think are going to impact it, but do it from a way that you think is going to be useful, clean, impactful. Pull out the ones that you don't think are useful. Yeah, you wanna make it be a good test. Don't just throw in as many tests as you can. If your incentive is to create as many tests as possible. Oh, so here's another way to say it. Input metrics in one case can be an outcome metric for another case. So if ship every day is influenced by input metrics, someone else farther down the road could be incentivized by saying my output is to create tests. So how do I create as many tests as possible? Does that make sense? And so for that you would wanna say creating good tests. And so what's the input for creating good tests? So these, like those can chain. You can chain all of that along. And so then you wanna find the good input metrics for that because then their customer is creating test cases, right? So a developer farther down the line, their goal is to create good test cases. And the key there is good. So what is a good test case? Catching as many defects as possible, running as quickly as possible. Does that answer your question? So for Western, so the question was how do you apply Western to a larger team or larger sets of teams? It's best if you keep it at the team level because people know what it feels like at the team level. But if you want to, you can change that instead of on my team responsibilities or shared or failure leads to inquiry. It can be at my organization. It was a little bit of, so how was it accepted, right? Cause sometimes people are like, whoa, a little bit of both, to be honest. So some of it was like, whoa, Nelly, like don't tell me that emperor has no clothes. Super don't wanna hear it. And some of it was, oh my gosh, finally we totally need to hear about the data, right? So, and that's kind of why I pointed out for the engineering thing. So capturing some measures through subjective means, doing the mini interviews to collect the data can be a really good way to do it because you're essentially socializing things. And you end up triangulating, right? So I've been researching this space since 2007. So I had a pretty good idea of what data we needed to be collecting and building hooks into the tools for. I had a really good idea of what we needed to do. Walking in and saying, so I'm the expert and this is what you're gonna build. Not a good way to do it. And I didn't do that. But there was like, I think I have a pretty good idea. I think I'd like to see this in our tools. I don't see it. So went ahead and like they did their thing. It was their initiative. Several of them came up and they said, it's looking like these end up being really good ideas. What do you think? I would like to get your advice on, your insights on what to build in. And I was like, thanks. I'm excited to hear that the team is ready. This is a great idea. This actually looks like it triangulates really well back into the things I've been finding through the industry. So like sometimes people joke and they're like, oh, surveys are all right. Yeah, except for the most part, people have really good intentions. And socializing that helps you build also exposure, right? Suddenly now everyone is also used to the idea of collecting some data and seeing some data. It kind of eases everyone into that. Who's responsible at Chef or when I see it in other organizations? Who's responsible for collecting metrics? At Chef, we have someone in engineering who is on like a special team who kind of helps but also the team leads at other organizations. It can be some that they bring in just to do metrics. Okay, thanks everyone. Thank you.


And when I'm in surrender to that Truth, which is the Antar-Guru, then what action, whatever it may be, whatever emerges from these lips, whatever emerges from this body, whatever action this body is taking, is emerging from the Truth, and when this body is not in surrender, then its actions are emerging from the ego. It's a simplification on that path to becoming and perfecting this whole system as an instrument of the Truth. So finally, this whole thing is Truth in action, after the deepening of the practice.


Can you outline the extra steps that you said the police would take when they're interacting with people? You said that first would be education. Can you just give a bit more detail about what that might look like? Sure, so right around New Zealand you will see the very friendly face of the New Zealand police. As we engage with people and educate people and we did have people overnight who claimed they knew nothing about this, knew nothing about the requirement to stay home. So very much in education. If people breach the requirements they will be warned and will keep a record of those people. If people do not comply the very next step is if there's no other way of doing this because we do want to take a very caring and compassionate approach to this. But if people won't comply we do have the authority to then detain them, take them to our place and put them somewhere that will allow them to contemplate the impact of their decisions.