Journal of Applied Physiology, Vol 53, Issue 1 294-296, Copyright © 1982 by American Physiological Society
A rapid technique for dynamic calibration of electromagnetic flowmeters
R. D. Hill
A new technique for the dynamic calibration of electromagnetic flowmeters
has been developed that uses a simple transistor circuit and is suitable
for both sine- and square-wave flowmeters. The magnet current is amplitude
modulated using a square wave at a frequency of 1 Hz to provide a suitable
input to the flowmeter. This input simulates the input that would have been
generated is a square-wave oscillatory flow had been passed through a flow
probe. The modulating square wave together with the square wave from the
flowmeter output are sampled using a digital computer, and comparison of
the Fourier transforms of the two waveforms yields a calibration of
amplitude attentuation and phase lag for frequencies up to 50 Hz. The
technique is very fast and thus allows multiple determinations of the
calibration, which in turn lead to a more accurate calibration that has
been achieved by other methods. The calibration of a Statham SP2202
flowmeter is presented providing an example of the technique.
