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A Complete Guide to Purchasing Reverse Osmosis Water Filter Systems


An Introduction to Water Filter Systems

The quality of tap water today has been significantly degraded as a result of human activities, especially industrial waste discharge. Toxic substances can be found in polluted water and finally spells severe threats to human health. Moreover, pollutants in the water have also posed new challenges to a variety of companies that demands the supply of water at a high level of purity, such as food manufacturing and processing companies, medical equipment manufacturers and electronics manufacturers. To cope with the threats to human being and the challenges to the industry, water filter systems have become increasingly popular to meet people’s demand for clean water.

Water filter systems improve the quality of water by removing contaminants and undesirable components and reducing their concentration. Water filter systems are crucial and beneficial to human health.

Water filter systems fall into many types. Different types utilize different water filter cartridges and have different purifying performance and applications.

Water filter systems that are most commonly seen on the market can be divided into the following types.


Ocpuritech-A Complete Guide to Purchasing Reverse Osmosis Water Filter Systems
Reverse osmosis system (RO)
A best and most popular water purification system

1. Reverse osmosis (RO) water filters. Reverse osmosis filters are among the most popular on the market. They were first seen in the United States and have dominated the market of water filter systems worldwide.


2. Ultrafiltration water filters. Ultrafiltration is another widely-used filtration method similar to reverse osmosis. Ultrafiltration technology can be used to treat water of different levels of quality. After processing, low molecular weight solutes are left in the water. Mineral water for sale we see on the market is usually processed with ultrafiltration technology.


3. EDI plants. EDI plants are mainly for industrial use rather than household use. They suit those industries that demand a high level of water purity such as medicine manufacturing.


This passage will give a brief introduction to reverse osmosis water filter systems that have won the widest range of customers on the market.


Before explaining what reverse osmosis is, we need to understand what the normal osmosis process is like. In the normal osmosis process, the solvent naturally moves from an area of low solute concentration to an area of high solute concentration. The driving force for the movement of the solvent is the reduction in the free energy of the system when the difference in solvent concentration is reduced, generating osmotic pressure due to the solvent moving into the more concentrated solution. Now, imagine that external pressure is applied to reverse the natural flow of pure solvent and such a process is reverse osmosis. Reverse osmosis technology was originated in the United States in the 1960s for aerospace science and technology research, and then gradually converted to civilian use. It has been widely used in scientific research, medicine, food, beverage, desalination, and other fields. A reverse osmosis membrane uses nanofiltration with pores in a size of approximately 0.0001 microns. Under certain pressure, H2O molecules can pass through the reverse osmosis membrane, and the inorganic salts, heavy metal ions, organic matter, colloids, bacteria, viruses, and other impurities cannot pass through. By this process, purified water and the brine can be strictly distinguished. The conductivity of the purified water after filtration can be as low as 5s/cm, which conforms to the standard of water at level III for laboratory use. If the water is further treated by an ion exchange system, its conductivity can be reduced to 18.2s/cm, which far excels the standard of water at level III for laboratory use.


Reverse osmosis water filters have become one of the most effective ways to purify your tap water. It can be a little overwhelming to pick the right option for a reverse osmosis water filter. Before you make your decision, it is recommended that you spend some moments thinking about the following.


1. What is the source of water to be filtered?

Different types of source water need different pre-filters. The pre-filter is a primary filter used to separate the bigger sand and sediment filters before a reverse osmosis system. It increases the life of filters inside the reverse osmosis filter. Since it is installed outside, it can be changed easily and frequently without opening the whole reverse osmosis purifier. A report on the water quality, if any, can better help you to decide what pre filters you will need.


2. What is the desired quality of the purified water?

Generally, the conductivity of the purified water after treated by a reverse osmosis filter can reach 20μm/m. However, if the conductivity of the purified water is required to be reduced to 1μm/s, one more set of reverse osmosis will be needed.


3. How to deal with the brine?

A reverse osmosis filter produces a clean stream of high purity water, and as well as a smaller stream of waste, referred to as concentrate or brine. Brine is a highly concentrated solution of the salts and contaminants separated from the water with the reverse osmosis membranes. There are many brine disposal methods available today, different by environmental and capital costs.


4. Is the space for the reverse osmosis filter enough?

Reverse osmosis water filters need some space for placement and the space needed to vary from type to type of the reverse osmosis water filter.


5. What is the volume that it is rated for?

The price of the reverse osmosis system varies depending on the rated amount of water that it can treat daily.


6. What is the rated voltage for industrial use?

The rated voltage for industrial use will narrow down available options of reverse osmosis water filters that you can choose from.


7. What about the cost and service life of accessories?

A reverse osmosis water filter will, from time to time, needs periodic maintenance and the intervals are dependent on the type of system that you have and on the quality of the water that enters the filters. The cost for maintenance and accessory replacement is also an important factor to consider before deciding which reverse osmosis water filter to buy.

What to Consider When Choosing Reverse Osmosis Water Filter Supplier?

1. A supplier in a major coastal city is preferred. Let’s take China as an example. A majority of suppliers of water filter systems in China tend to be clustered in Shandong, Hebei and Guangdong provinces, among which, Guangdong Province is the most preferred. To begin with, buyers can find the most complete product lines in Guangdong Province. It is more time saving to find all the products needed and arrange for the delivery. Moreover, Guangdong boasts the most developed transportation facilities nationwide and buyers tend to ship the goods from ports of Guangdong Province. More importantly, companies in Guangdong Province have abundant experience in international trade and are able to provide better service.


2. Make clear whether the supplier is a factory or a trading company. A factory manufactures the products itself while a trading company sources a variety of products from one or more factories. The downside of a trading company is that they typically have higher prices than factories as they take some markup over the factory and you will have less control over the actual production of your goods.


3. The industry of water filter systems is a demanding industry in terms of qualification, experience, and technological accumulation. Be sure to find out whether your supplier is qualified or experienced enough to deliver satisfactory products.


4. Make sure that the supplier is a legally incorporated company and it has experience in international trade. This can facilitate your import process.


5. Make sure the supplier is experienced in major projects of water treatment.


6. Check whether the products have been certified and whether the supplier can provide any quality assurance.


7. Make sure that the supplier provides after-sales service.


8. Be sure that the supplier is able to satisfy your personalized needs.


9. Check whether the supplier can provide a complete supply of spare parts and accessories for replacement.


A Closer Look at a Reverse Osmosis Filter System

A reverse osmosis filter system is operated by a programmable logic controller (PLC), including its normal operation, reverse washing, system protection, water flushing and cleaning of reverse osmosis device. Other equipment is operated manually. A complete reverse osmosis filter system generally consists of the following components.

Ocpuritech-A Complete Guide to Purchasing Reverse Osmosis Water Filter Systems-1
Reverse Osmosis Filter System

1. Multi-media Filter

Each filter is equipped with complete valves, monitoring instruments, internal connecting tubes, and various accessories. The sampling bucket is installed in a convenient position for operation and maintenance. The pressure gauge is provided with an isolation valve, and the device body is provided with a peephole.


1) Manufacturing Requirements

a. Anti-corrosion treatment is required for the inside of the system.


b. All internal pipelines should be connected to the main body by flanges, while the convenience for inspection and component replacement should also be considered. The materials of the internal components are in compliance with the specified requirements, and the fasteners are equivalent to the internal pipe fittings.


c. The internal components should be fixed and reinforced to withstand the impact of the water flow.


d. The material of the equipment should be transparent and corrosion-resistant. Its thickness should withstand the rated pressure of the container and the test pressure during the test. The inner surface of the sight glass should be flush with the inner surface of the container.


e. The manhole of the container should ensure the access of the maintenance personnel and the entry and exit of the replacement parts. The inner surfaces of the manhole and manhole cover should be even with the inner surface of the container. The manhole should be equipped with a full set of parts such as a manhole cover, washers, bolts, nuts and lifting rods.


f. All container internal devices, fittings, components, etc. should be installed and fixed in the container before shipment to prevent omission of parts or damage or loss during transportation.


g. The equipment should be in support of withstanding feet.


2) The upper inlet device of the filter should be a baffle-type water inlet device, and the lower drainage device should be a perforated plate.


3) A flow meter should be arranged on the inlet pipe of each filter, and a pressure gauge is arranged on the inlet and outlet pipes.


2. Reverse Osmosis Filter

Although the system that we mention herein is referred to as a “reverse osmosis filter system,” the reverse osmosis filter is only one stage of the system. The reverse osmosis filter includes security filters, high-pressure pumps, reverse osmosis membrane modules, supporting instruments, valves, piping, and body racks, and chemical dosing equipment.


1) Security Filter

The structure of the security filter should be suitable for quick replacement of the filter element. A drain valve should be provided on the water pipe that enters the security filter.


2) Reverse Osmosis Booster Pumps (Pressure Pumps)

The booster pump should be a vertical multi-stage pump. The pipes and accessories should be made of stainless steel.


The booster pump outlet should be equipped with a flow restrictor (to control the opening speed of the valve) and a pressure switch to prevent the membrane assembly from being affected by excessively high pressure, and alarming or stopping the pump when the retarded pressure is high.


The pressure switch should be installed on the membrane module to cope with the impact of excessively high pressure and high retarded pressure and pump stop signal.


The sealing method had better be corrosion-resistant in a mechanical manner.


The reverse osmosis booster pump inlet should be equipped with a pressure switch to alarm and stop the pump when the pressure is low. The outlet should be equipped with a switch to alarm and stop the pump when the pressure is excessively high.


3. Reverse Osmosis Device

The reverse osmosis device consists of two trains. They can operate independently from each another or simultaneously.


The reverse osmosis membrane should be selected according to the characteristics of water quality. Membranes with large water permeability, high salt rejection, good chemical stability, and excellent mechanical strength are preferred.


The rated water flux of the reverse osmosis membrane should not excel the minimum water flux specified by the membrane element. Different types of reverse osmosis membranes should be arranged in a logical manner to ensure the normal operation of the membrane and a reasonable cleaning cycle.


According to the characteristics and requirements of water quality, the types of dosing and dosing locations for water supply should be clearly specified. The drugs used for the chemical cleaning solution should be determined by the quality of the source water and the characteristics of the reverse osmosis membrane adopted.


The inlet pipe, each section of the brine pipe and the purified water pipe of the reverse osmosis system should be provided with sufficient interfaces and valves for connection with the inlet and outlet pipes of the cleaning liquid during cleaning.


The brine pipe should be equipped with a (solenoid) flow control valve to control water recovery.


The reverse osmosis filter should be designed to protect the membrane element from backpressure.


The reverse osmosis filter inlet pipe and purified water pipe should be provided with sampling points. The number and location of sampling points should effectively diagnose and determine the operating status of the system.


4. Cleaning System

A cleaning system includes cleaning tanks, cleaning pumps, security filters, electric heaters for cleaning tank, and pipes, valves, meters, etc. All equipment should be assembled on a chassis to form a unit. The material and anti-corrosion coating of the cleaning system should not be vulnerable to the cleaning solution. The cleaning tank should be equipped with an electric heater.

 5. Flushing System

The flushing system includes flushing pumps, valves, pipes, etc. When the booster pump is stopped, the flushing pump should also be stopped. The control of the flushing system should be run in an automatic manner while should be started manually.

 6. Reverse Osmosis Piping

The piping of the entire reverse osmosis system avoids dead ends to prevent bacterial growth. A flushing system should be introduced. The booster pipe should be made of stainless steel with corresponding medium corrosion resistance with its outer surface polished.

 7. Dosing System

A complete dosing system should be provided according to the requirements of the reverse osmosis system. Types, concentration, amount of the drugs and relevant instructions should be specified.


Each dosing system should be designed to be separated as a unit. Each set of the dosing device should be provided with a solution box, a metering pump, valves, pipes and so on.


The volume of various drug solution tanks should be sufficient for the dosage for one day and one night. A local liquid level indication and remote liquid level indication should be respectively installed, and alarm signals should be given when the liquid level is too high or too low.


The body of the solution tank should be made of corresponding corrosion-resistant material.


The dosing device can automatically adjust the dosing amount according to the flow rate.


The stroke of the metering pump should be adjustable from 0 to 100%, and the output should be 1.25 times the maximum dosing amount. The measurement accuracy at the point of maximum stroke (100% relative stroke) should not be less than 1%. The metering pump should receive the flow signal and automatically adjust the dosage. Metering pumps of high quality imported from relevant operating experience supplier are preferred.


The valve should be configured according to the process requirements. Connecting valves should be corrosion-resistant. The dosing pump should be designed for continuous operation. The pump should be arranged to facilitate testing, replacement, and overhaul of all components.


All metal and non-metal parts that come into contact with liquid should be resistant to the corresponding liquid.


Addition of drugs should be based on the low-level alarm signal of the drug dissolution tank and the instructions of the operating personnel.


Where Can Reverse Osmosis Filter Systems Be Put Into Use?

1. Electronics Industry

Reverse osmosis system is mainly used to produce tube glass bulbs, picture tubes, liquid crystal displays, circuit boards, computer hard drives, integrated circuit chips, monocrystalline silicon semiconductors, etc., which demands pure water and high purity water.

2. Heat Boilers

Low-pressure boilers are required in some mining companies, and the water used in these boilers requires to be demineralized or desalted pure water.

3. Pharmaceutical Industry

Reverse osmosis systems can be used to manufacture infusion solutions, injections, pharmaceuticals, biochemical products pure water, sterile water, artificial kidney dialysis pure water, etc. required for medicine.

4. Beverage Industry

The manufacturing of beverages and wines requires purified water, distilled water, mineral water, brewed water, pure water for blending with other solutions, etc.

5. Desalination

 Desalination is an open-source project for water conservation. It can produce agricultural irrigation water and domestic water, but drinking water has not yet become popular.

6. Electroplating Process

Reverse osmosis systems can be used to prepare pure water for battery, automotive, household appliances, building materials, surface coating, and coated glass; as well as desalted mineral water for textile printing and dyeing.

7. Petrochemical Industry

Pure water is required for the manufacturing of chemical reaction cooling water, chemicals, fertilizers, fine chemicals, and cosmetic products.


8. Purified water is required in some high-quality water supply network systems for hotels, buildings, residences, airports, real estate property, and swimming pools.


9. Purified water can be used for circuit boards, electroplating, electronic industry wastewater treatment, and reuse.


10. Purified water can be used for the treatment of domestic, hospital, tanning, printing and dyeing, and treatment of paper industry wastewater and landfill leachate.


In this passage, we will focus on why hospitals, farms and food companies need water filter systems.


1) Hospital Water

The water used for medical purposes should not contain bacteria and viruses. The special environment determines that the source of water must be treated with professional water treatment equipment. The pure water treatment equipment required by the hospital is relatively demanding, that is, the ultra-pure water treatment equipment and reverse osmosis equipment.


Reverse osmosis is currently the best water purification treatment process and plays an important role in the medical industry. It is mainly used to manufacture medical infusions, pharmaceuticals, syringes, biochemical pure water, medical sterile water, and dialysis water.


2) Aquaculture Water

Advantages of aquaculture water treatment equipment can be boiled down to the following.

a. Livestock Safety

Water purification equipment can effectively remove E. coli, Salmonella, pesticides and fertilizer residues, sediment, redness, rust, etc. in the water, so that livestock can drink clean and hygienic water.


b. Quality of Poultry Meat

Purified water can prevent infected animals from infecting bacteria and reduce the use of drugs, thus greatly improving the quality of the meat.


c. Decrease in Livestock Death

Purified water reduces the risk of livestock disease, livestock mortality and reduces the cost burden, thereby reducing the risk of the reproduction.


d. Improvement in Livestock Production

Feeding poultry with clear water can regulate the micro-ecological balance of the intestines of the birds, enhance immunity and increase animal husbandry production.


e. Environmental Protection

Water treatment systems do not produce wastewater that pollutes the environment.


3) Food Water

The water source used in food production and processing must be supplied by pure water equipment and must meet the corresponding standards, so as to ensure the safety of food production water. Here are some factors that will affect food quality.


Hardness is one of the most common and most important indicators. It is mainly reflected in the concentration of calcium and magnesium ions in water. High hardness will cause discoloration, precipitation, flavor change, and hardening.


Alkalinity in excess of the normal range will lead to a decrease in the flavor of the food, precipitation, and abnormal growth of yeast.


Smell of the water is easy to affect the flavor of the finished food.


Chromaticity and turbidity in excess of the normal range can cause precipitation, difficulty in carbonation, and color change.


Moreover, the pH of the water and the phenols, free chlorine, dissolved oxygen, nitrates, organic matter, heavy metals and microorganisms in the water may also affect food processing.


For these reasons, the impurities in the water must be removed by water filter systems to meet the corresponding standards with relevant physical and chemical indicators suited for food production and processing.

A Guide to Purchase of Industrial Water Filtration Systems

Ocpuritech-A Complete Guide to Purchasing Reverse Osmosis Water Filter Systems-2

Industrial water filtration systems

1. What Are Industrial Water Filtration Systems?

Industrial water filtration systems are water purification equipment for industrial purposes developed with new reverse osmosis technology.

2. What Are the Main Differences Between Industrial Water Filtration Systems and Household Water Purification Equipment?

The membrane of a household reverse osmosis machine is characterized by small volume and small flow rate (50GPD, 75GPD, and 100GPD are among the most common). A household reverse osmosis machine is portable and is generally installed in the kitchen. It is usually 5 stage, 6 stages, 7 stage, and that consumables will need to be replaced after 3-6 months.


Industrial water filtration systems, apart from in families, feature longer service life and larger filter area, and can also be used in various industries such as food industry, electronics industry, hotels, medical industry, farms…


There is a wide range of options in terms of capacity. 250LPH, 500LPH, 750LPH, 1000LPH, and 5000LPH are among the most popular and some machines with a large capacity such as 15TPH, 20TPH are also widely adopted.


1. What Impurities Are Filtered by Industrial Water Filtration Systems?

Industrial water filtration systems mainly remove sediment, residual chlorine, odor, bacteria, viruses, heavy metals in the source water, reduces calcium and magnesium irons, turbidity, and hardness, and removes salt from the water to make the water suitable for drinking.


2. Operating Principles of Industrial Water Filtration Systems

Industrial water filtration systems make pass the source water through a quartz sand filter, a granular activated carbon filter, a softening filter, a precision filter, etc. The water is then pressurized by a pump and passes the pores with a diameter of 0.00001μm (1/6000 of the size of E. coli, virus and 1/300 of viruses) of the reverse osmosis membrane. The water with high concentration becomes less concentrated. About 99% of the salt, industrial impurities, heavy metals, bacteria, viruses and other impurities mixed into the water can be removed and physical and chemical indicators and hygiene standards of drinking can thus be satisfied.


Industrial water filtration systems can handle different water qualities, such as natural water, groundwater, rainwater, river water, borehole water, seawater, brackish water. However, wastewater should not be treated by industrial water filtration systems. Standard reverse osmosis equipment can handle water quality below TDS 2000ppm.


In the case of brackish water and seawater, seawater desalination equipment should be used. Water of TDS 35000ppm or less can generally be treated.


3. Installation and Maintenance of Industrial Water Filtration Systems

1) Installation of Reverse Osmosis Filtration System

a. Analyze and test whether the water inlet of the system meets the requirements. The water is allowed only when the test result proves to be up to standard.


b. Adjust the pressure control system of the high-pressure pump.


c. Check the pipeline of the device. Make sure that the connection of the low-pressure pipeline is tight and the pressure gauge is normal.


d. Switch on each pressure gauge and the inlet valve, brine discharge valve, and purified water discharge valve.


e. Start the pretreatment equipment and set the water supply amount to be greater than the total water intake of the system.


f. Backwash and flush the sand filter of the system of the industrial water filtration systems until the water is clear.


g. Start the high-pressure pump and slowly switch on the inlet valve of the system. The total inlet pressure of the control unit should be less than 0.5Mpa. Flush for 5 minutes, and check whether the high and low-pressure pipelines and instruments are normal.


h. Adjust the inlet valve and the brine discharge valve to make the inlet pressure between 1.0-1.4Mpa.


i. Detect the conductivity of the purified water. Open the outlet valve and close the production water discharge valve when the requirements are met.


j. All steps for testing the reverse osmosis system should be manual in a step-by-step manner. After the operation is normal, it can be switched to the automatic state to allow the online instrument and PLC to automatically control the operation.


k. Start the regeneration system of the industrial water filtration system to see if it works properly or not.


2) Maintenance of Reverse Osmosis Filtration System

a. Backwash of Pretreatment System

i) The quartz sand filter must be manually backwashed within 3-5 days of normal water production in accordance with the backwash operation instructions.

Turn off the high-pressure pump, pure water pump and open the booster pump under normal water purification process of the equipment;

Adjust the handle above the filter to the backwashing position (for 15 minutes)

Adjust the handle to the flushing position to flush (for 5 minutes)

Reset the handle (to the normal water production position)


ii) Activated carbon filter should be immediately backwashed after the quartz sand filter.



Reset the handle (to the normal water production position)


   iii) Softening filter should be immediately backwashed after the activated carbon filter.

Rotate anti-clockwise the red button of the automatic controller to the backwash position

The following operation will be automatically controlled (backwashing, salt absorption, hydration, flushing and reset). The staff member should remind that salt should be added to the salt bucket after the completion of the hydration in this process for future use.


  iv) Immediately after the completion of the backwashing, the pure water machine should be started for the normal water purification process. Start the booster pump first and then start the high-pressure pump at the automatic position. It is forbidden to leave the equipment before the water purification is completely restored.


b. Reverse Osmosis Filter

In the case of the normal water purification process, the sediments inside of the reverse osmosis filter should be carried out from time to time.

Switch on the flushing valve;

Switch the high-pressure pump to the manual position;

Flush (which generally takes 1~3 minutes);

Reset the switches to the normal water purification position. 

Staff members should remind that flushing should be carried out no less than 3 times a day to ensure a sediment-free environment in the reverse osmosis filter and the performance stability of the system.


Factors to Be Attended to for Small Industrial Water Filtration Systems

Operators of small industrial water filtration systems should be aware of some precautions. Accurate operation and proper maintenance are the guarantees for the long-term stable operation of small industrial water filtration systems. Here are some factors that need to be attended to during the operation of small industrial water filtration systems.


1. Pre-filter material should be prevented from entering the reverse osmosis filter. A good filter outlet can prevent the leakage of sand and activated carbon. Activated carbon of good quality can prevent powder removal during use.


2. The permeability of the membrane increases with the water temperature, but high temperature accelerates the hydrolysis of the membrane and makes the organic membrane soft and easy to compact. Therefore, for the organic membrane, it is preferred to control the temperature between 20 to 30 °C.


3. In order for reverse osmosis to proceed, the pressure applied must be such that the pressure difference across the membrane is greater than the osmotic pressure difference. The operation pressure should be determined by the concentration of the source water as it relates to the osmotic pressure difference. In addition, it is also affected by the permeability of the membrane and water recovery rate. In general, increasing the operating pressure will increase the amount of water produced. But, if the pressure is too high, the membrane will be compacted and the water permeability will decrease.


4. In order to avoid clogging the reverse osmosis system, the source water should be pretreated to eliminate suspended solids and reduce its turbidity. Moreover, sterilization should be carried out to prevent the growth of microorganisms in the system.


Transportation and Packaging of Industrial Water Filtration Systems

Because of the relatively large volume of industrial water filtration systems, sea shipping is preferred by the vast majority of customers. Each system should be enwound with clean film to avoid scratches and wear, and then be placed in a solid wood box to ensure safe transportation during the long shipping.

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