Whats this fitting on my compressor pump?

[rcx132]

Theres a brass fitting on the back of the outlet on my compressor pump. It seems to allow air through. I don't know if it auto shuts at a certain pressure or what, any ideas?

 

[carbon]

Its a pressure relief valve/safety valve, it has the pressure rating marked on the end face but cant quite make it out in your last picture

 

[rtbcomp]

It closes at about 20psi. It's purpose is to allow the motor to run up to speed before putting it under load, usually fitted to compressors with a non-delayed unloading valve. This function is usually performed by a delayed unloading valve in the switch, but on some compressors both methods are used (eg my Clarke compressor).


The safety valve will be fitted to one of the ports in the pressure switch, and may have a ring which you pull to test it.

 

[rcx132]

It closes at about 20psi. It's purpose is to allow the motor to run up to speed before putting it under load, usually fitted to compressors with a non-delayed unloading valve. This function is usually performed by a delayed unloading valve in the switch, but on some compressors both methods are used (eg my Clarke compressor).


The safety valve will be fitted to one of the ports in the pressure switch, and may have a ring which you pull to test it.

That sounds plausible. It reads NA BAR 2.2.

2.2 bar equates to 31 psi.

 

[rtbcomp]

IIRC the pressure in the tank gets to about 20 psi, so the pressure at the intercooler will be higher.

When I got my compressor I thought it was faulty when I first tried it, there's nothing in the instructions about it.

 

[rcx132]

IIRC the pressure in the tank gets to about 20 psi, so the pressure at the intercooler will be higher.

When I got my compressor I thought it was faulty when I first tried it, there's nothing in the instructions about it.

The pressure in the intercooler is much higher. I once tried using 150psi hose to connect the pump to the receiver once.... did not last.

 

[rtbcomp]

That was probably due to the heat. I tried that with plastic air hose, it just softened and burst.

 

[rcx132]

That was probably due to the heat. I tried that with plastic air hose, it just softened and burst.

Sure, the heat is problem A, but there's more to it. The air coming out the compressor pump comes out in pulses, and the pulse peaks exceed the tank PSI. So the hose/pipe between the pump and tank needs a higher PSI rating plus heat rating.

I'm having to make my tank remote from the pump now (will explain why later), so I need some flexy hose to go from the pump to the tank. I've got something called "steam hose", but now the hose clamps (jubilee clips) keep blowing. I've found some heavy duty cast iron hose clamps but very pricey. Was going to see if I could get some hydraulic hose with 1/2" BSP ends made to measure, might be cheaper seeing how cheaply brake lines are made, maybe hydraulic lines are just as cheap.

 

[Farside]

maybe hydraulic lines are just as cheap.

A local hydraulics place might surprise you.
I've found them to be reasonably priced compared to what I was expecting, going by prices for the same hoses online, etc.

 

[carbon]

Hydraulic hose isn’t really rated to withstand the high temperature that can be at the outlet of a compressor. Have seen hydraulic hose used, connected directly to the pump outlet but it has to be replaced periodically as it starts to leak after a time.