SIP Compressor leak at control unit

[alanbp]

Hi

I am new to the forum. I have a 3 year old 3hp 50 litre SIP and just after switching it on and it running for a while on saturday there was an almighty hissing coming from the underneath of the control box. As soon as I pull up the switch the air escapes, and stops when I put it back down. The motor sounded like it was stalling and struggling to turn while this was happening.

I stripped the box down last night and it seems that the air is coming out through the small hole at the top end of the black plastic pipe, There appears to be a small brass pin in there but it is totally down in the top of the pipe, ie not stuicking out, but I am assuming that it is supposed to come up out of the top of the black pipe and push into a small metal lever at the bottom of the switch?

I tried clamping the pipe (the compressor started normally & started charging the tank - I ran it to 60 psi then relased the clamp on the plastic pipe, hoping it would clear the sticky pin - but no luck and immediately the air began escaping and the motor began to stall - so I switched off pronto.

I contacted SIP yesterday (I hadn't stripped it then) and he recommended a completely new control unit but wanted the guts of £50.

Can anyone recommend a fix for this or a cheaper source of spares?

Many thanks in advance

Cheers

Alan

 

[eil]

Has the compressor been stood for a long time without you using it ?. these switches tend to stick at times, the one on my wolf does anyways, bit of wd40 and flicking of the toggle, power disconnected obviously. it then behaves itself.
http://www.machinemart.co.uk/shop/p...t-20-amp-3-phase/path/accessories-consumables

 

[alanbp]

Thanks eil

It tends to get used at least once a week mostly tyres etc and occasional heavy use with impact wrench, paint/shutz spraying etc. I have been using it a lot recently, although to my shame, I am not too scupulous at draining the tank of accumulated water!!

The clark control units in your link, I presume they would work just as well on my SIP compressor?

Cheers

Alan

 

[rtbcomp]

The switch lever is operated by a diaphram, not the valve on the plastic pipe.

The pin you mention is operated by the switch to open the valve when the cut-off pressure is released. The down position opens the valve.

Air should escape from that valve 1) until pressure reaches about 20 psi or 2) when the pressure switch cuts off. (NB - sometimes there is a seperate valve for function 1)

Those pressure switches MM sell are pretty universal.

Not sure why the motor starts stalling once it's running, it will struggle to re-start if that valve doesn't open once the switch cuts out.

 

[alanbp]

I notice, looking at the MM control units there is an attachment underneath presumably for the small plastic pipe. Would I just cut the "valve" off the top of the existing SIP plastic pipe and secure it to underside of the new control unit?

My SIP compressor has the ' "sticky valve" plastics bit with the brass pin' at the top of the plastic pipe.

 

[rtbcomp]

The plastic connection is most likely a "push-fit" type, if so look where the pipe enters the valve, there will be a plastic ring round the pipe. Push this ring towards the body of the valve and the pipe should be released.

 

[alanbp]

Problem solved!

Checked the non-return valve on the side of the tank and there was a small fragment of aluminium fin (not good that its come through the piston etc) stuck in the valve causing it to stay partly open and letting full tank pressure come out of the plastic pipe. Removed it and reassembled and everything is working as it should. This also explains the motor stuggling as it was fighting full tank pressure with the NRV being partly jammed open.

The compressor fell over on a concrete floor the other week and broke part of one of the cooling fins and mashed up the air filter box - I think one of the fragments was sucked in and has ended up at the NRV. I had a worrying moment when It was all bolted together - and the motor wouldn't run - turns out the fuse on it has tripped - obviously due to the overload on the motor.


Thanks for all help so far - feel I have a much better understanding of how these machines work now.

Alan