Flow Meter Calibration Partial

Hello! The purpose of this Instructable is to familiarize you to flow meter calibration. There are two different types of flowmeter that will be demonstrated. The paddle wheel flowmeter and the Venturi flowmeter. In the lab, all flowrates recorded increased approximately linearly with the measurement systems, which was what was intended.

A paddle wheel flowmeter works by allowing the flow to spin a paddle, which generates a current across a fixed resistance, creating a measurable voltage which can be related approximately linearly to the flowrate. These are used in gas stations all over the world. In fact, knowing that they struggle to measure extremely slow moving liquids could help you save money on gas! To expand on this, paddle wheel flowmeters are generally accurate at higher flowrates compared to lower flowrates. Unfortunately, the data from our lab only went up to 17ft/s however the data was approximately linear up to

A Venturi flowmeter uses a manometer, a differential pressure transducer, and a thinner section of pipe in order to calculate flowrate. Venturi flowmeters also use a coefficient called the discharge coefficient. It can estimated to be equal to one, but in reality decreases as the diameter of the thin section approaches the diameter of the thick section. In the lab, the calculated values were not close to unity whatsoever. So, instead of estimating it to be unity create a relationship of 1-(value determined by diameter ratio). In fact, since our lab measured discharge coefficients were approximately .7, using 1 as the discharge coefficient value would actually cause the flowrate to seem much higher than it actually is.