Error in pressure gauge

[ushang70]

HI,

i am using Mechanical Pressure gauge in hydro tester system, where as in every five minutes time pressure rise to 120 Bar from zero. in every shift we need to calibrate the gauge in front of quality fellows, and within day or two almost all pressure gauges are showing errors. Can anybody guide me to resolve the issue.

 

[MikeHalloran]

Is the gage rated for 120 bar? 150 bar? What?

Is the gage equipped with a damper, or does some other scheme limit the rate of pressure change up/down seen at the gage?



Mike Halloran
Pembroke Pines, FL, USA

 

[IRstuff]

How do you even know they're in error?

What happens when you calibrate, i.e., how does offset/gain change from calibration to calibration? Where is your engineer in all of this?

TTFN
faq731-376

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[LittleInch]

I agree we need more data such as the accuracy you are trying to achieve and the range and size of the instrument. Pressure guages should last 100,000 hrs + before needing to be calibrated to +/- 1% of full range / zero accuracy if you've got a good guage, but if you have any damping or excessive pressure fluctuations you can need it much more, but every two das sounds like ther eis omething seriously wrong here, either in the testing or the guages.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[ushang70]

Dear Mike,

Gauge range is 280 BAR
it is within +-1% accuracy, Least Count is 2 Kg, Dial Diameter is 10".
at calibration it shows minus side error on Dead weight Tester. it is happened with almost all brands of gauges, since last 15 days i have changed five gauges.Yes it is Glycerine filled.

IRSTuff

in every calibration different error is found, i can say there is no consistency in errors. Pl. forget about my engineers, they are unable to solve this so i came to this forum.

Littleinch,

i will come back with schematic diagram of system.

 

[MikeHalloran]

Did you notice that the dead weights on a Dead Weight Tester are round?
... and that they nest into each other, so it's hard to knock them off?

They're made that way so that you can gently and slowly spin the entire dead weight assembly during the measurement, so that packing friction can't cause an offset.

Does your calibration procedure include spinning the deadweight?



Mike Halloran
Pembroke Pines, FL, USA

 

[IRstuff]

Again, what are you using to judge that the gauges are in error? Have you checked into contamination or some sort of damage to the gauges

TTFN
faq731-376

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