Magnetic flowmeter calibration
Magnetic flowmeter calibration
(OP)
Our company owns a 12" magnetic flowtube and transmitter from the Rosemount company, but it's pretty old. The meter is installed in a flow test system for cast iron valves, and may be subject to erosion from sand and rust particles. We (I) am now in the process of trying to update the calibration for the meter, which becomes pretty expensive for this size meter. Rosemount advertises their current models of mag meters as having the capability to be recalibrated in-line (essentially via software, by measuring the circuit characteristics at a no-flow condition).
Questions -
1) has anybody used this recalibration system, does it really work? Does it account for wear and/or filming on the meter i.d.?
2) Do you know if the in-line calibration can work for older models of flowtubes/meters, and/or other manufacturers' models; does this require the transmitter to be changed to the Rosemount version?
Thanks for any help/advice.
Questions -
1) has anybody used this recalibration system, does it really work? Does it account for wear and/or filming on the meter i.d.?
2) Do you know if the in-line calibration can work for older models of flowtubes/meters, and/or other manufacturers' models; does this require the transmitter to be changed to the Rosemount version?
Thanks for any help/advice.





RE: Magnetic flowmeter calibration
RE: Magnetic flowmeter calibration
FYI, that's what the meter manufacturer eventually said too, they can calibrate the transmitter, and tell you whether they think the system (meter+tube) is out of cal., but it's not a true calibration.
RE: Magnetic flowmeter calibration
Given the way a magmeter works the transmitter check is pretty good, but traceability requires flow proving. Just spend the money to have a flow prover certify the installation. Or, just remove the meter and return it to a flow test facility (Rosemount has one) for flow testing and calibration.
In-house checks are possible and accuract if you have the tankage, but not certifiable. If you were certifying flow measurement devices accuracy would be a real issue, but valves? What are your flow accuracy requirements for the valve test +/- 5%?
There are a half dozen other approaches that are more or less time consuming and even more expensive.
RE: Magnetic flowmeter calibration
Yoou can also send the meter to the University of Utah-water research lab, where they have a NIST setup and measurung tank for large diameter meter calibration.
Regards,
RE: Magnetic flowmeter calibration
Well...a) we can certify a prover (i.e. a tank) volume pretty accurately (well below 0.5%), with traceability to NIST, using various techniques...and timing, if done electronically on narrow segments of vertical tanks, with fairly smooth flow profiles, can be awfully accurate too. We've gone this route and established a NIST-traceable calibration to within +/-0.5% on volume flow.
But, yes, it gets expensive and time consuming to do this. That's why the idea of "calibrate in place" appealed to the boss; Rosemount advertises that its transmitter calibration qualifies as a flowmeter cal. for several gov't. agencies. I buy the premise, but as noted above, it ain't traceable so it ain't calibrated.
b) Our valves act a bit like flowmeters, but yes, +/-5% is all we guarantee; we want to certify to within 1-2%. And yeah, I can certify the meter about a dozen different ways, but it all comes down to $ and time.
Golestan, there a lots of places who can calibrate a meter, but thanks anyways for the tip.
Thanks for the help/suggestions, good discussion.