How to Calibrate a Flowmeter

Flowmeters are devices used to measure the flow rate of a liquid. This procedure will focus on venturi, orifice-plate, and paddlewheel flowmeters.

Before taking any fluid measurements, always check that the discharge valve is closed and level all manometers by bleeding air out of the pressure transducers as necessary.

First, make sure that there is no flow in the test section and zero the pressure transducer output. Then open the manometer bleed valve and take readings of transducer output and manometer levels. Make sure that the maximum voltage does not exceed 10 volts. This software will find the slope and intercept of the data you've collected and use it later during data analysis.

Open the discharge valve slowly, stopping only when maximum allowable manometer height is reached or when valve is fully open. At this point, record the manometer and paddlewheel readings, take a weight-time measurement, and record the pressure transducer voltages. Repeat these measurements for 0.9^2(h_max), 0.8^2(h_max), 0.7^2(h_max), ..., 0.1^2(h_max).

LR.2. The data in the log scaled graph do not appear linear which is not indicative of a power-law relation.

Q.2. The Discharge Coefficient is not constant over the entire range of Reynold's numbers. These Cd's are not entirely in line with the theory. The theory could be amended by mathematically taking into consideration turbulence, friction, and other small deviations from the perfection that is modeled by the theoretical equations.

Q.4. The paddlewheel flowmeter is very well synced up with the venturi flowmeter. The reading was equally accurate at both low and high flow rates.