Sanden compressor output PSI and heat

Of all the threads I searched, I never found any reference to this. Does anyone know, or has anyone ever measured, what PSI comes out of a Sanden compressor at idle?

I don't realistically know a lot about A/C systems (except in theory), but I thought it was a couple hundred pounds on the high side. I'm kinda confused. All articles have a 150 PSI relief valve as a safety, so I have to assume that the output is less than that until a tank or air line builds up to the 125 PSI pressure to operate the pressure switch.

The other issue I was thinking about was the heat from the output side. The coolest idea of someone's I read about was a copper coil the size of a coffee can to dissipate heat. Well, thinking back to the routing of the hoses before I removed them all, wasn't the high side plumed to the condenser? So, couldn't I send the compressed air through there (after oil removal) and get cool air out? I was going to remove it, but decided to leave it in there to catch bugs and rocks that would otherwise hit the radiator while on the road.

On the OBA setup I had on another vehicle the air hose off the compressor melted out from the heat so I simply put about 3 feet of coiled copper tubing right off of the compressor. Much like on a garage compressor. It took out enough heat to save the hose.

The 150psi relief valve is to protect other components in the A/C circuit--such as the condenser and evaporator. Thew compressor would probably top out at around 200 psi., going directly into a tank, hope full for safety reasons. that's rated for 200psi pluss.
Don't think you'll get appreciable cooling of compressed air using the condenser, but certainly more than you'd get without it. Probably better than a coil of copper tubing. And yes, the compressor high side outputs to the condenser.

I think the 150 psi in the articles was when were converting to OBA so you don't blow up your tank or tools with too much pressure? On the a/c system. the high-side relief valve is 500-600 psi according to my 1995 FSM. Normal high-side operating pressures on a R134a system range from 150 to 350 psi depending on ambient temperature and the freon charge. Not sure about the cfm rating of the compressor when used as OBA, but it should be at least comparable to a 5hp standalone electric compressor

I have my pressure switch set to turn the Sanden off at 125psi. The hose gets hot where I have it slid over a barbed fitting, so occasionally I just chop an inch off and slide it back onto the barbed fitting.

cLAYH said:

On the OBA setup I had on another vehicle the air hose off the compressor melted out from the heat so I simply put about 3 feet of coiled copper tubing right off of the compressor. Much like on a garage compressor. It took out enough heat to save the hose.

Click to expand...

X2.

My initial setup had PVC hose running from the high side of the compressor to the input of the relief valve/pressure switch/filter setup, and one field test revealed that the output is hot enough to soften the PVC and blow it off the barbed fitting (yikes!). I'm pretty sure that the temp was high enough that the hose would have burst eventually if it had not blown off the hose barb.

2 1/2 loops of 3/8" copper tubing (about 4" dia loops), painted with flat black BBQ paint dissipates enough heat to keep the temp reasonable. I also replaced the short section of PVC hose between the copper loop and the rest of the system with rubber tranny cooler hose. Gates hose, rated for hot oil (250 F +) and 150 psi or so. The tranny cooler hose is $$$ so I only used it for that part of the system that saw high temps and oil in the air.

Ian