Campbell compressor melting unloader line

[whipped383]

I have a Campbell air compressor that's melting the plastic tube coming out of the check valve over to the unloader. What would cause this to happen? Iv noticed the unloader kicks off at around 145 psi but on the tank it says 125psi max. Could that be the problem that the compressor is working to much to get the extra 20 psi that it makes enough heat to melt it?

Here's some pics specs on the compressor check valve on top of tank with push connect fitting and the nicely melted tube my quiet air filter made from reading this board (had problems before filter change).

 

[m4rkz0r]

1st post I see. Welcome to the forums!

I'm no air compressor expert, but I'll take a stab at it. Those pressure switches seem to come on a lot of air compressors these days. IIRC the cover pops off and there and some adjustment screws to change the cut on pressure and cut off pressure. There may be instructions under the cover on how to adjust it. It could also be the gauge itself giving incorrect pressure readings. I would also check the pressure relief valve and make sure its functioning.

As for that line have you repaired it already and it keeps doing the same thing? I guess it could be melting from the extra work to get 20 psi. Personally I would use some copper or aluminum tubing, bend it to fit, and use compression fittings.

Hope that helps!

 

[platypus20]

If there is any leak in the unloader line or unloader, hot air right out the compressor will melt the plastic line. check to leaks in the line.

 

[Zeke]

Too much pressure = heat. Even any higher pressure = heat. Agree on the copper and agree on dialing it down. Lasts longer, saves power.

 

[Milton Shaw]

Single stage compressor like that one are designed with 125 psi about the max on them. A two stage usually is set about 175 psi with one stage and then cooling before the same air is compressed again in the second stage. Even then most of the single stage compressor would have metal lines instead of plastic as that is going to get hot as the compressor works too hard to reach that extra 25 psi. Go to a two stage or turn the pressure switch down to cut down on extra wear and heat from over compressing the air.

 

[gtermini]

I fought one of these lines on a Campbell Hausfield service truck compressor. It was a constant duty gas powered one that would unload when the tank hit 180 psi and then keep running. The plastic lines wiuld melt in about an hour of running and copper line work work-harden and split in a few days. Final solution was to just have a 3/16 ID braided stainless line with JIC ends pressed up. Never had another issue. Line was about $100 to have made.

Greyson

 

[Fixnair]

Your discharge temp would be in the range of 350*. Far too high for plastic tubing. Your compressor would have to run for at least 10 minutes to reach that temp if the pump were in good shape. If your pump is worn out it would run hotter and would need to run longer to maintain the pressure compounding the situation. I would change it to copper, vibration will not be a problem for you if your compressor is electric driven.

 

[whipped383]

Well is this my problem?
I can never build a full tank without it melting and blowing the line, forget continued use.

Using a copper line is something iv thought about it just seems like a bandaid to me. I looked at the parts manual and it shows a plastic line. Iv repaired it many times and it's dot air brake tubing. The parts manual also shows having a 120 psi cut out switch. I think I'll order a new switch and see what happens. This was a second hand compressor so I'm sure what's on it was just thrown on there. I'm also wondering if the compressor isn't wore out. I pulled the head off last week and everything looks really good, there was a bit of carbon on the reeds and I cleaned them all u but the cylinder shows no sign of wear. I also don't get any oil in my tank, I pulled the petcock right out and left a bucket under it while I went to the store for a new one and had less than a cup of pretty clean water.

 

[m4rkz0r]

That's interesting, the switch has a different cut on and cut out pressure than the tank. Like you said, if its second hand who knows what's been done to it. Before buying a switch you can try adjusting the cut on and cut off pressures on the switch you already have. I did a bit of Google searching and I think I found a PDF for that switch that explains how to adjust it.

https://www.google.com/url?sa=t&sou...8QFjAA&usg=AFQjCNG6OEuuKspWMLvD2sSm-nis2tsRsw

 

[whipped383]

Looking at that PDF I'll have a hard time adjusting it to the pressure range I need. I order a new switch for 30 bucks. In the process of all this I find no safety valve and no strain relief on the motor cord. Gotta love people right!

 

[m4rkz0r]

Hahaha... the things people do. Reminds me of a sanborn compressor I bought at a pawn shop. I had to talk them down because someone removed the pressure relief valve, unloader valve, and pressure switch and had it wired to run continuous; you had to manually shut it off or something would eventually explode.

 

[whipped383]

Well iv ordered new parts, gotta make this thing safe before I can diagnose any further. I'll report back with what I find

 

[whipped383]

Well I got the new switch on yesterday that seemed to do the trick. I'll post back after more long term testing.

One question tho, with the new switch the shutoff pressure seems a little high. Will the spring in it loosen up over time or should o adjust it to what spec is?

 

[AP514]

I would adjust it to your needs.....mine adjust with a simple turn of the screw.

 

[CompressorPros.com]

Adjusting the pressure down would definitely help. Most have an adjustment screw with a spring. Clockwise raises the pressure and counterclockwise reduces it. There are also different types of unloader line that can withstand higher temps.