Testing Pressure Gauges

[stbenjamin]

What's the best way to test pressure gauges for not a lot of money? It seems a lot of the gauges on our CO2 regs are off and we'd like to at least know how far each is off for carbonating, kegging, etc

[NHBrewer23]

The easiest and least expensive method that I can think of is to setup a manifold system with a T-fitting. On one end of the T-fitting, use a TC adaptor to connect a regulated CO2 line to the fitting. Using 1/4" NPT to TC adaptors found on GWKent.com, purchase an ASTM certified pressure gauge with a 1% accuracy (found on omega.com). Use this gauge to validate other gauges. Using another 1/4" NPT to TC adaptor, screw in any gauge that you suspect being off. Bring in a regulated pressure into the T-fitting and compare the two gauges. I hope this helps.

[Starcat]

Additional measures

The easiest and least expensive method that I can think of is to setup a manifold system with a T-fitting. On one end of the T-fitting, use a TC adaptor to connect a regulated CO2 line to the fitting. Using 1/4" NPT to TC adaptors found on GWKent.com, purchase an ASTM certified pressure gauge with a 1% accuracy (found on omega.com). Use this gauge to validate other gauges. Using another 1/4" NPT to TC adaptor, screw in any gauge that you suspect being off. Bring in a regulated pressure into the T-fitting and compare the two gauges. I hope this helps.

You can also port in as above and connect a digital transducer such as Fluke PV-350. These are made ot work with your multi meter.
Not necessarily cheap, but accurate.

http://www.zoro.com/g/00030224/k-G2456885?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CKvGwMSimsACFeg7MgodhScAVw

Or set up a permanent panel mounted industrial transducer readout next to your main analog gauge on the manifold.

[fstmatt]

T-fitting, one side to pressure gauge and the other to tubing that runs vertically upwards as high as your ceiling will allow. 138 inches(11.5 feet) of water column = 5 psi. Kinda hard to verify high pressure gauges with this method unless you have really high ceilings, but it is very accurate.

[stbenjamin]

The easiest and least expensive method that I can think of is to setup a manifold system with a T-fitting. On one end of the T-fitting, use a TC adaptor to connect a regulated CO2 line to the fitting. Using 1/4" NPT to TC adaptors found on GWKent.com, purchase an ASTM certified pressure gauge with a 1% accuracy (found on omega.com). Use this gauge to validate other gauges. Using another 1/4" NPT to TC adaptor, screw in any gauge that you suspect being off. Bring in a regulated pressure into the T-fitting and compare the two gauges. I hope this helps.

Thanks! Getting the right gauge was my stumbling block. I can't seem to find anything labeled ASTM on Omega's site, do you have a model you can recommend?

[Larry Doyle]

The easiest and least expensive method that I can think of is to setup a manifold system with a T-fitting. On one end of the T-fitting, use a TC adaptor to connect a regulated CO2 line to the fitting. Using 1/4" NPT to TC adaptors found on GWKent.com, purchase an ASTM certified pressure gauge with a 1% accuracy (found on omega.com). Use this gauge to validate other gauges. Using another 1/4" NPT to TC adaptor, screw in any gauge that you suspect being off. Bring in a regulated pressure into the T-fitting and compare the two gauges. I hope this helps.

Good answer. That's the best way.

[CDangerBrew]

The easiest and least expensive method that I can think of is to setup a manifold system with a T-fitting. On one end of the T-fitting, use a TC adaptor to connect a regulated CO2 line to the fitting. Using 1/4" NPT to TC adaptors found on GWKent.com, purchase an ASTM certified pressure gauge with a 1% accuracy (found on omega.com). Use this gauge to validate other gauges. Using another 1/4" NPT to TC adaptor, screw in any gauge that you suspect being off. Bring in a regulated pressure into the T-fitting and compare the two gauges. I hope this helps.

This is also a great way to pressure test PRV's.

[stbenjamin]

Just a bump, I haven't been able to find anything labeled ASTM on Omega's site.

[soia1138]

I don't believe it will be labeled as such. The important factor is finding the gauge with a 1% accuracy. PGM-100L-15PSI/1BAR. This is the stainless gauge on omega with a +/- 1% accuracy

[TGTimm]

Just a bump, I haven't been able to find anything labeled ASTM on Omega's site.

Well, here you go: http://www.omega.com/pptst/PGT-PGL.html Not cheap, but you only need one.

[TGTimm]

You can also port in as above and connect a digital transducer such as Fluke PV-350. These are made ot work with your multi meter.
Not necessarily cheap, but accurate.

http://www.zoro.com/g/00030224/k-G2456885?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CKvGwMSimsACFeg7MgodhScAVw

Or set up a permanent panel mounted industrial transducer readout next to your main analog gauge on the manifold.

What is the output on this? mV/psi? Our Fluke meter only reads to 1mV. Would this work for us?

[TGTimm]

I downloaded the Fluke specs for the pressure/vacuum module. It will read to the nearest 1 unit using our DMM, but using a DMM that reads to 0.1 mV, it will read to 0.1 unit. 1 psi resolution is fine for checking/calibrating our pressure gauges, so I've got something new on my wishlist. Thanks.

[Starcat]

Additional Uses

This rig will also behave similar to a Micron guage for deep vacumn use.
I have found them useful.

[TGTimm]

I finally settled on (and got--see below) an SSI Tech. MG-50-A-9V-R digital media gauge. This is not as accurate as some of the suggestions, but, at +- 0.125% of full scale, is quite good enough for calibrating analog 0-30 psi gauges. I set it up with a simple manifold incorporating a small low-pressure regulator, so I can connect it to our air supply (regulated to 90 psi) and slowly dial up the pressure to test a gauge throughout it's range.

The first thing I tested was the gauge on our Zamh&Nagel SS-60. WOW! when the Z&N gauge indicated 14 psi, the digital gauge read 22! I tossed that one and replaced it with a spare that tested near perfect, and our bottling line foaming issues have vanished. Time to re-calibrate the ol' bio-Zahm now!

Testing brand new Ashcroft liquid-filled gauges has been educational, as they generally have been off by ~+- 1 psi. These are not calibratable (unless you pull the needle and move it), so I note on the gauge whether to add or subtract from the indicated reading, and how much. If a gauge is more than +- 1 psi, I toss it. I'm now looking for calibratable low-pressure gauges to gradually replace the ones we have. Suggestions welcome.

One important thing to note if you plan on buying this gauge: Grainger, Zoro.com, Drillspot.com, and others all are sourced from Grainger. Grainger has the wrong stock number on these gauges. You won't get the MG_50 (0-50 psi), instead, you'll get the MG-500 (0-500 psi). What's the big deal? Note that the accuracy of this gauge is +- 0.125% of FULL SCALE. That means that the MG-50 should be within +- .25 psi, while the MG-500 would be +- 2.5 psi. One is acceptable for calibrating my gauges, the other not.

I finally got the right gauge from Kodiak Controls (SSI's main distributor), and it cost considerably less than from the other sources. I'll be doing more business with these folks in the future.

[TGTimm]

Gauge tester

Here's a pic of my pressure gauge testing set-up. I just need to build a mount for it before I drop the thing and break it.



On the left is a bleeder valve to relive pressure. The test gauge is next, an SSI MG-50 digital media gauge. The gauge being tested screws into the gauge port on the top of the output side of the low-pressure regulator. Shut-off valve and plug for our air system QD on the right. Various parts allow hooking up gauges of different stem sizes and orientations. 2" TC flange is for testing PRVs and PCVs, as the test gauge has a high-pressure hold to let me know the pressure the PRV or PCV went off at. Works pretty well, and the regulator allows me to check the gauges for linearity over the scale.

The gauge being tested is 1 psi high at 10 psi. Brand new, too. I'll label this gauge "-1" to indicate that 1 psi needs to be subtracted from the reading.