Compressor Help

[NeilThornely]

Hi everyone, I'm new to the forum but this seemed to be a good place to come and learn a bit more about workshop tools.

Anyway - we have a SnapOn WSEC35/200 Compressor and it seems to have a bit of a leak. While the tank is filling (and for a few seconds after it's turned off) you can hear it leaking air out of the joint I've marked with an arrow.

The joint leads back to the motor so I'm pretty sure it's the cutoff valve that stops the motor running when the tank reaches it's maximum allowable PSI.

The problem I have now is I'm s**t scared of leaving the thing to reach maximum in case it explodes! I know the tank will be rated to way more than the motor is capable of but I don't want to find out. We've tried taking it out and tightening the joint with the allen key bit at the back (not shown in the photo) and it still leaks.

Any ideas?

Thanks in advance

 

[rtbcomp]

Welcome to the forum.

There is a valve (the unloader valve) inside the switch which opens to unload air from the pipe between the pump & the tank when the motor stops.

If it's letting air out whilst the pump is running it's not closing properly, this could be a faulty valve, valve actuator or a bit of dirt trapped in the valve.

If it lets air out for more than a quick burst after the pump has stopped the non-return valve (NRV) is letting air through, again this could be a worn valve or bit of trapped dirt.

The NRV is the bit where the thick pipe from the pump enters the tank.

Either of these faults won't cause the tank to over-pressurise as long as the motor stops when the tank reaches pressure.

If the motor doesn't stop, the switch may be faulty. A split diaphragm will cause this and let air out of the switch. This could be confused with air leaking from the unloader valve.

Some diagrams here http://www.mig-welding.co.uk/forum/media/albums/compressors.206/

 

[NeilThornely]

Cheers very much for that