Where to put the Valve and Pressure Gages? - Rotameters
Description of Application
Rotameters are far and away the least expensive flowmeters for gas flow rate applications. However, many users or potential users are not well versed in the technology involving the relationships between flow rate, static pressure and pressure drop for compressible fluids (gases). Nor are they aware that gas temperatures and pressures affect rotameter readings (and sizing) because of the effect on gas density.
Typical Installations
- Controlling flow rate into a sub-atmospheric pressure (vacuum)
- Controlling flow rate into a pressurized system
- Passive measurement with back pressure on meter
- Passive measurement discharging to the atmosphere (no valve)
- Controlling bleed off a system with variable pressure into a lower but constant pressure
Notes
- The pressure in the Tube is that which is used to size the Rotameter and prepare the scale. There can be no valve or other restriction between the Pressure Gage and the Tube.
- Be certain not to specify a meter for operating at a pressure higher than its pressure rating.
- If the pressure at the source is above the rating of the meter, a pressure relief valve should be installed in the line between the pressure reducing valve and the flowmeter.
Installed How?
