Magnetic Flow Meter

It depends on the brand and model, but it would surprise me if a magmeter did not have a means of forcing its output for a loop check. If the output can be forced, then there's no for additional test equipment. The manual for the Siemens magmeter on the bench here shows either a 'current output' or 'digital output' function in menu service group, either of which can be put into 'force' mode at a selected output value. Check the manual for your magmeter for something similar.