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Pressure Gauges
- Thread starter Jorg50
- Start date
There is a video and a professional calibration is a multi step precision procedure with expensive equipment The face and the pointer come off. Precision weights apply pressure to a liquid column that the gauge is attached to. The gauge is checked against the standard at several points and a setting is picked that gives the best compromise over the range of the gauge. The alternate calibration standards are electronic and cost thousands, more than the mechanical standards. If all you want to know is what adjusts the calibration, find and watch the video. After the range is adjusted the zero will have moved so then the pointer can be put back on.Does anyone here calibrate pressure gauges?
What is the right procedure?
I am talking the analogic pressure gauges.
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racingtadpole
Well-known member
The test unit is called a deadweight tester, there's plenty of information available online about them and how to use them. Adjusting the gauge under test is generally a case of adjustment of the internal spring tension across various points within the range of motion to achieve the most accurate reading. It doesn't take long to get the hang of how to do it, but it does require a bit of patience. It's a cool old school instrumentation skill to have, even if there isn't much call for it today.
What's the application of the gauge?
What's the application of the gauge?
This is all predicated on having a dead weight tester; not something most can justify the cost of for casual calibration. You have to pay before you can play. Thanks for the info.The test unit is called a deadweight tester, there's plenty of information available online about them and how to use them. Adjusting the gauge under test is generally a case of adjustment of the internal spring tension across various points within the range of motion to achieve the most accurate reading. It doesn't take long to get the hang of how to do it, but it does require a bit of patience. It's a cool old school instrumentation skill to have, even if there isn't much call for it today.
What's the application of the gauge?
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lakeroadster
Well-known member
Does anyone here calibrate pressure gauges?
What is the right procedure?
I am talking the analogic pressure gauges.
I worked at a company that made pressure vessels. The procedure we had was to always have a certified gauge that was sent out yearly for calibration to NIST standards. That gauge never left the tool room and the certification papers were on file with the QC Manager.
When a gauge was needed on the shop floor the "certified" gauge was used to test the "shop" gauge by the tool room attendant.
We had a series of gauges. Only the center 1/3 of the range was used. So, for instance, a 0-300 psig gauge was only used for applications where the pressure was between 100 and 200 psig. We had quite a few "certified" gauges.
Did you recalibrate your service gauges that the toolroom gauge found out of spec or chuck them or send them out for recal?I worked at a company that made pressure vessels. The procedure we had was to always have a certified gauge that was sent out yearly for calibration to NIST standards. That gauge never left the tool room and the certification papers were on file with the QC Manager.
When a gauge was needed on the shop floor the "certified" gauge was used to test the "shop" gauge by the tool room attendant.
We had a series of gauges. Only the center 1/3 of the range was used. So, for instance, a 0-300 psig gauge was only used for applications where the pressure was between 100 and 200 psig. We had quite a few "certified" gauges.
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Stooge
Well-known member
More than what i expect your looking for but ; i work in a force calibration laboratory, with multiple deadweight stacks for creating reference standard load cells, although we send out our digital pressure gauges to be certified and calibrated. i just looked at one of the certs for them, and this is the piece of equipment used to calibrate them at our vendor, (ILAC, A2LA, NIST accredited, as are we) if your interested. A Fluke High gas pressure controller/ calibrator, a PPCH-g 618 to be specific for the gauge cert i pulled up. http://us.flukecal.com/literature/product-manuals/ppch-g™-operation-and-maintenance-manual
chrism0107
Well-known member
- Joined
- Jun 4, 2012
- Messages
- 252
You will need a calibrated reference to be able to test and adjust a gauge. I have often used a calibrated fluke process meter to verify the accuracy of gauges and send them to our instrument shop for adjustment if they are out of tolerance usually 2% of full scale by contract
lakeroadster
Well-known member
Did you recalibrate your service gauges that the toolroom gauge found out of spec or chuck them or send them out for recal?
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We had some really large diameter gauges, those we would send out for re-calibration.
The smaller ones, 3", we would typically just throw away and buy new.
engineer2
Well-known member
About every major city has a metrology lab. What is used to calibrate a pressure gauge should be at least 4x more accurate than the gauge being calibrated. Most inexpensive gauges are throwaways since the $100+ NIST certification charge plus repairs/adjustments may cost may be more than a new NIST traceable gauge.
NIST certs are expensive because of the cost of purchasing and maintaining the equipment. The NIST traceable calibration equipment must be sent out (usually) annually to be recertified, so a cal lab really needs two sets for whatever pressure ranges they do.
NIST certs are expensive because of the cost of purchasing and maintaining the equipment. The NIST traceable calibration equipment must be sent out (usually) annually to be recertified, so a cal lab really needs two sets for whatever pressure ranges they do.
akdiesel
Well-known member
I used to calibrate pressure gauges with a calibrated weight device.
Once the weight was equal on both sides you reinstalled the needle to the correct setting. I found that in most cases. Just simply removing the needle and putting it back to zero PSIG I was close to a calibrated gauge I had just done.
Of course if the needle was way out range I would recalibrate it correctly.
Once the weight was equal on both sides you reinstalled the needle to the correct setting. I found that in most cases. Just simply removing the needle and putting it back to zero PSIG I was close to a calibrated gauge I had just done.
Of course if the needle was way out range I would recalibrate it correctly.
Provincial
Well-known member
I had a gauge that would go way out of calibration. It turned out to have a bad tooth on the sector gear. It only reached that tooth if the pressure was higher than normal.
Unless you want to spend plenty of money on the correct standards be happy with just verifying your gauges are close with another. Procedure wise, exercise to full scale a few times and the check 5 cardinal points. 20 to 90% of scale approaching from bottom of scale. Check hysteresis on a point on the way back down scale and adjust as needed.