Testing Steam Gauges

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one_inch_railroad
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Testing Steam Gauges

Post by one_inch_railroad »

Does anyone have any ideas on how to test the accuracy of a live steam guage? I have some from American Model Engineering Supply and was wondering if there is anyway to test them to see how accurate of a reading they give for setting safety valves and during operation
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cbrew
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Re: Testing Steam Gauges

Post by cbrew »

how many do you have? your post sounds like you have many,
if so, test them against themselves. if they are ready with in a pound or two, I would trust them to be accurate. but then again, it is possible for a "batch" to be bad.

Most clubs will have a certified gauge used during hydro testing, that is where i would compare your gauges too..
just a thought
If it is not live steam. its not worth it.
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Trainman4602
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Re: Testing Steam Gauges

Post by Trainman4602 »

The official way to check any pressure gauge with the exception of oxyacetylene gauges ( use no oil) printed on the gauge, is to use a dead weight gauge testing devise.
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hammermill
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Re: Testing Steam Gauges

Post by hammermill »

not sure i would do that with a oxygen guage either. lacking a fixture as above. many testing and calibration labs exist with differient levels of traceable calibration.
kbarnett
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Re: Testing Steam Gauges

Post by kbarnett »

I have access to an Ashcroft 1305D dead weight tester and have used it to check my USG 200psi gauges with. It works on the same principle as Dave's drawing in the previous post.
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RichD
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Re: Testing Steam Gauges

Post by RichD »

"A Deadweight Tester for Pressure Gauges":
http://www.nmpproducts.com/tester.htm
Fact is, a known good gauge is still needed
when you build your own.
The weights must be bought or made and the piston,
cylinder set varified.

Each steam club should own a calibrated 300 psi gauge
for member use on annual boiler hydro day.
A 4" 1% panel gauge will do nicely and are not too pricey.
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Steve Bratina
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Re: Testing Steam Gauges

Post by Steve Bratina »

You don't require a good gauge for a dead weight tester. It uses multiple weights to test a gauge.
The unit is not cheap or practical for occasional use. If you buy a good steam gauge in the range you require, (1 1/2 to 2 x dial range) you can use it as a comparator to the other gauges. Boiler inspectors used to carry such devices to verify the gauge on the operating boilers in a plant.
To use it, make up a header to attach several of your gauges you want to test and the test gauge. Use air to test. You require accuracy in the range from the popping pressure down to about 30 psi below that. A gauge can't be accurate through its whole dial range. If you need to, the test gauge can be calibrated every few years depending on use. It should be used only for comparative purposes only and not as a working gauge on an engine.
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H&NERY
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Re: Testing Steam Gauges

Post by H&NERY »

If I am not mistaken, in 1 of Kozo's books it descries how to build a pressure gauge and tester, I just off hand don't remember which one.
David_T
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Re: Testing Steam Gauges

Post by David_T »

Kozo's Heisler and Climax books
one_inch_railroad
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Re: Testing Steam Gauges

Post by one_inch_railroad »

Thanks for all the info guys. I guess I will pick up one of the kozo books and make myself a dead weight tester. Has anybody on the forums made one. Is there a lot of work involved?
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Chris Hollands
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Re: Testing Steam Gauges

Post by Chris Hollands »

You really must be bored if you want to build a gauge tester ,if you have a air compressor with a gauge just set it up and see if it matches your air compressor gauge or compare it to someones gauge that you know maybe your local club boiler inspector,if it seems to be close to the air compressor gauge then it is probably ok if it is out by 5 or 10 pounds then you may have a issue.
Or go buy your self a small calibrated gauge from a hydraulic fitting supply company or gauge company (wika or someone similar )if you really want to be right and save your self a lot of work and money by the time you dick around.
Just my 2c worth
alanstepney
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Re: Testing Steam Gauges

Post by alanstepney »

I feel that everyone should have access to some form of standard, that is KNOWN to be accurate.

Now, whether that is a calibrated gauge at their club, a dead weight tester or whatever, is unimportant.
What does matter is that they can be sure that thir "usual" gauge is accurate.

Now, calibrated gauges are expensive, and having them checked regularly is also an expense.
So, a dead weight tester is an excellent thing to have, or have access to.

They are simple to build and provided that are made with reasonable care, are very accurate.

As an aside, and provided we are discussing steam, digital temperature gauges are now very cheap.
If you can measure the temperature of steam, you can tell its pressure.
Of course, you need to ensure that it really is the actual steam temp you are measuring.
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