# Flow

Flow includes flow transmitters, flow sensors, flowmeters, sight flow indicators, and water meters. Mass flowmeters, controllers, flow indicators and controllers are ideal for measurement of flow rates. Flow switches come as paddle, thermal, piezo, and shuttle/piston.

## QUESTIONS

Question
How are Dwyer flowmeters properly read?
The flow rate is read at the maximum width portion of the float regardless of shape.
Question
What factor is used to correct for different flowmeter inlet pressure?
If the flowmeter is exhausting to atmosphere, no correction factor is needed. If back-pressure is present due to downstream plumbing or restrictions, this error can be corrected utilizing the conversion curves in our full-line catalog or the following equation.

Pressure: Q2 = Q1 x √((P1 x T2)/(P2 x T1))

Where:
Q2 = Standard Flow Corrected for Specific Gravity
P1 = Actual Pressure (14.7 psia + Gage Pressure)
P2 = Standard Pressure (14.7 psia, which is 0 psig)
T1 = Actual Temperature (460 R + Temp °F)
T2 = Standard Temperature (530 R, which is 70°F)
Question
Why are top mounted valves recommended for flowmeters used for vacuum service?