Working pressure of an air condition system.

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Today, I had to bend an a/c pipe on a tractor. It ended up fitting the way it should, but it seems I've made a pressure mark in it. The wall thickness of this pipe is about 0.04'', so this mark is likely a very weak point now. The pipe I am dealing with is the one between the compressor and the condenser. Just to get an impression of the stress on this pipe: What is the maximum working pressure of an a/c?
 
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JHZR2

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For R134a, high side is roughly 240 psi, low side about 35. When not on, the equilibrium pressure is about 80 psi. THese are all rough and vary by a fair amount.
 
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I do some automotive AC work and the maximum I would put into a system is 2 1/2 times the ambient temp measured on the high pressure side. The rule of thumb is get the high side pressure about 2 times the temperature outside and see if the system is cooling good enough. If not, continue to add refrigerant until it cools well or you have reached 2 1/2 times the temp. Of course try to imitate what ever air flow will occur in the normal operation of the vehicle to get closer to real world conditions. And try to err of the side of caution - don't want to bend any reed valves and have to buy a new compressor...
 

Extreme-Duty

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Thanks, that's probably the info I needed. And yes, it's R134a refrigerant. Nice instruction, rob! The pipe I've bended is the 180 degree hose fitting connected to the compressor. I assume the hose between the compressor and the condener is on the high pressure side. It might be wild speculation, but I would not expect 450 PSI to blast this pipe. Is pulsation an issue in these systems? Also, is there some kind of corrosion protection in the refrigerant?
 
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 Originally Posted By: Extreme-Duty
Also, is there some kind of corrosion protection in the refrigerant?
The PAG oil would protect against corrosion, and R-12 or R-134A are chemically very inert substances, and would not cause corrosion of internal components. If there's moisture, or if there's air in your lines, then you didn't pull enough of a vacuum on the system prior to filling.
 
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 Originally Posted By: Extreme-Duty
Thanks, that's probably the info I needed. And yes, it's R134a refrigerant. Nice instruction, rob! The pipe I've bended is the 180 degree hose fitting connected to the compressor. I assume the hose between the compressor and the condener is on the high pressure side. It might be wild speculation, but I would not expect 450 PSI to blast this pipe. Is pulsation an issue in these systems? Also, is there some kind of corrosion protection in the refrigerant?
High-side pressure will vary a lot depending on application. I've worked on R134A systems that would barely top 200psi on a 100 degree day... and I've worked on other systems that could easily see 350psi. Depends on condensor design, refrigerant charge, air flow... lots of things. While 450psi might be possible in some applications, I've never seen it. The highest head pressure I recall seeing in a properly functioning R134A system is maybe 350-375psi. I would be very surprised if your tractor's system went higher than that. As for bending that high-side line: so long as it's properly clamped in place and isn't being subjected to excessive stress and vibration (and it won't be if the lines are properly clamped in place and parts aren't pulled tight or anything), then I wouldn't worry about it. I've never seen a steel a/c line break due to the pressure- they always fail due to excessive rust, or flexing and vibration. Unless your compressor is failing, pulsation should not be a problem.
 
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 Originally Posted By: Extreme-Duty
Thanks, that's probably the info I needed. And yes, it's R134a refrigerant. Nice instruction, rob! The pipe I've bended is the 180 degree hose fitting connected to the compressor. I assume the hose between the compressor and the condener is on the high pressure side. It might be wild speculation, but I would not expect 450 PSI to blast this pipe. Is pulsation an issue in these systems? Also, is there some kind of corrosion protection in the refrigerant?
Pulsation in systems varies depending on compressor design. Some systems have a muffler designed to reduce the noise from it. It is a bulbous aluminum thing in between refrigerant hoses and is not the filter/drier. I usually see them on older compressor designs that had enormous compressors with few cylinders. So I don't know what he has, but if his tractor was factory filled with R-134A, he has a compressor with several cylinders, a rotary vane compressor, or a scroll compressor, none of them would make much pulsation.
 
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