Rotameters & Manometers

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Rotameters and pressure gauges

For water and panel mount reverse osmosis. and Glycerin gauges from 0 to 100 psi and 0 to 300 psi.


Rotameters are simple industrial flow meters that measure liquid or gas flow in a closed tube. Rotameters are widely used because they have linear scales, a relatively large measuring range, low pressure drop, and are simple to install and maintain.

Rotameters belong to the group of meters called variable area flow meters, which measure flow, allowing the fluid to travel through a conical tube where the cross-sectional area of the tube is. This gradually becomes larger as the fluid travels through the tube.

The flow within the rotameter is measured using a float that is lifted by the fluid based on the buoyancy and velocity of the fluid opposed to gravity that presses the float down. In the case of gases, the float responds only to speed.

The float moves up and down within the conical tube of the rotameter in proportion to the speed of fluid flow. It reaches a constant position once the fluid and gravitational forces equalize. Changes in flow cause the float of the rotameter to change position within the tube. Since the float position is based on gravity, it is important that all rotameters are mounted vertically and oriented with the widest end of the cone at the top. It is also important to remember that if there is no flow, the float will go to the bottom of the rotameter due to its own weight.

Rotameters can be calibrated for other fluids by understanding the basic principles of operation. The accuracy of the rotameter is determined by the accuracy of the pressure, temperature, and flow control during the initial calibration. Any change in the density and weight of the float will have an impact on the flow reading of the rotameter. Additionally, any changes that affect the fluid, such as pressure or temperature, will also affect the accuracy of the rotameter. Given this, the rotameters should be calibrated annually to correct any changes in the system that may have occurred.