303-20 How to calibrate the funnel of hall flowmeter?
Choose the emery with particle size less than 106 micron as standard sample. When tested on a standard funnel using the method specified in this standard, the standard sample shall have a fluidity of 40±0.5s/50g.
AS-300A Automatic Hall Flowmeter
303-1 What kind of instrument is the hall flowmeter?
Hall flowmeter https://www.aimsizer.com