How to calibrate flowmeters and velocity meters

All instrumentation systems need calibrating to allow removal or correction of systematic errors introduced into the measurement by transducer and other systems component inaccuracies. In some cases, where system components are subject to drift, or where extreme accuracy is required, a calibration procedure may be used many times a day. In other cases, where long-term stability of components is good, calibration may only occur once a week or once a month. Without such calibration, credibility in the results of the measurement cannot be established.