Mitigating the Effects of Pulsating Flow in Flow Measurement
10 Mar 2021
Titan Enterprises has published a technical article that discusses how variation in flow velocity can impact flow measurement accuracy and how to mitigate any undesirable effects.
Flowmeters are sensitive to effects such as pulsating flow, which can generate errors in flow measurement. Pulsating flows can occur in systems using diaphragm, peristaltic or piston pumps. In a pulsating flow system, the velocity profile of the flow undergoes a dramatic change during each cycle of pulsation compared to even flow conditions.
According to theory, accurate measurement in a pulsating flow scenario requires the sampling rate of an electronic flow meter to be at least double the frequency rate of the pulsations themselves. If the pulsation rate is not taken into account, aliasing of the flow signal will be seen, resulting in erroneous measurement from the flowmeter.
Titan's Atrato and Metraflow ranges of ultrasonic flowmeters are able to resolve the ultrasonic signals to about 50 picoseconds. With downstream signal processing, the instruments can accurately measure pulsating fluid flow that is less than 10Hz. Accurate measurement of pulsating flows above this frequency requires inline pulse dampening.