Pressure testing a compressor

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wptski
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Pressure testing a compressor

Post by wptski »

I'm in the middle of pulling out an HR6 from a 1990 Buick for a leaky shaft seal. I replaced the seal two years but it never held up but unsure if I installed a double lip seal or not.

A while back I ran across compressor testing adapter not if it was a Santech, FJC, etc. and there were no details as to what compressor it was for. I'm going to make one to pressure test the seal now when removed and after I install the new one with nitrogen. Normally a system test would be maybe 150psi or so I've read. Since this is the compressor alone, can/should I go higher? The seal when running is under low pressure but when off the system equalizes and the seal would have a higher on it. The is also a R134A converted vehicle.

Funny when convert it held 150psi! A backup vehicle in the spring time, I had a puddle of oil.
mk378
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Re: Pressure testing a compressor

Post by mk378 »

Parts such as the compressor case that are on the low side are only designed for 150 psi or so. Having the case burst could cause you injury or death.
GM Tech
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Re: Pressure testing a compressor

Post by GM Tech »

Never heard of parts of a compressor designed for 150 psi just because it is on low side-- I worked for Delphi as a product egr on compressors- all compressors burst testing we did were near 1000psi- and always blew out an o-ring-- just to let it be clear. Plus I have seen equalized gage set pressures- both high and low side at over 220 psi- in Lake Havasu Az. at 120 deg ambient after a hot shut down and heat soak. Just sayin'
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wptski
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Re: Pressure testing a compressor

Post by wptski »

Made my manifold adapter up and put the N2 to it. I isolated the compressor with about 105psi but since there was only 10psi in the system when I checked, I left it there. After hearing that it's going to be much cooler tomorrow but N2 pressure doesn't vary with temperature as much as air, I forgot to bleed the air. While doing that I put 120psi on it but it dropped immediately to around that 105psi range again so it won't hold 120psi and probably leaks slowly over a long period of time. It was charged the second time in the spring of last year, never driven as it blew a brake line in May and I just finished replacing all the lines.

I'll see what it look like tomorrow and might try some soapy water around the at 120psi.
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wptski
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Re: Pressure testing a compressor

Post by wptski »

It lost 10psi overnight but using soapy water can't detect any leaks in the compressor or my connections. Since it's deadheaded using a clutch plate tool on the threads you can only rock it back/forth which makes the pressure go up/down a little. Put 150psi overnight and it hardly moved at all. Bleed off a bit so I could rotate the shaft to a different position and its held 4-5 hrs. Confusing....
Auto Engineer
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Re: Pressure testing a compressor

Post by Auto Engineer »

So you guys must live in very hot climates then, our static pressures are normally 5 bar and yours are approx 10.5 bar. Our ambient temperature over here is approx 21 degrees C, so maybe yours is double at about 42 ish degrees C ?
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wptski
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Re: Pressure testing a compressor

Post by wptski »

Auto Engineer wrote:So you guys must live in very hot climates then, our static pressures are normally 5 bar and yours are approx 10.5 bar. Our ambient temperature over here is approx 21 degrees C, so maybe yours is double at about 42 ish degrees C ?
Some areas do get that high. At 21C many wouldn't even use A/C! Where I'm at we hardly get over 32C but this summer has been the hottest ever so we had many days over that temperature.
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wptski
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Re: Pressure testing a compressor

Post by wptski »

New double lip shaft seal overnight at 150psi, no loss.

I found a PDF from the UK on pressure testing for various refrigerants and it listed 13.7bars or 198.7psi for R134A. I first boosted it to 175psi for three hours with loss so what the heck, at just under 200psi for thirty minutes, no loss.
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bohica2xo
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Re: Pressure testing a compressor

Post by bohica2xo »

150f under hood temps are common. Here in Las Vegas at 115f (46c) ambient the under hood can be 160f - which is 300 PSI on 134a

A car heat soaking after shutdown will see high temps on everything under the hood.
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wptski
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Re: Pressure testing a compressor

Post by wptski »

bohica2xo wrote:150f under hood temps are common. Here in Las Vegas at 115f (46c) ambient the under hood can be 160f - which is 300 PSI on 134a

A car heat soaking after shutdown will see high temps on everything under the hood.
The under the hood should be higher than that as they have increased coolant thermostats to over 200F increasing engine temperatures for better emissions.
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