Help needed please with pressure regulator

[gerrymoore]

I've just bough an ABAC 150 compressor - 240 volts single phase 3HP - it was advertised as 'faulty' on EBAY. You can see from the pics it's in very good condition and there's nothing wrong with the pump or motor.

I had a word with the guy when I collected it and he showed me the problem...it seems that the small air tubing going to the regulator is leaking air quite badly at the regulator...he also told me that the 'other end' where it goes into the tank had been replaced with a new 'pastille' I think he said??.

So...do I need a new regulator or is there some way of tightening the tubing up..I can't see any way it comes off?? Also the gauge didn't seem to read any pressure even though the tank did fill with some air??

Sorry...although I've had compressors for years I've never come across this

 

[rtbcomp]

That's the pressure switch - not the regulator.

The "pastille" he refers to is the rubber disc that forms part of the non-return valve (I've called it the "plunger" in this diagram).

If you're sure the air is leaking from the pipe then it can only be the non-return valve, if air still leaks from the switch with the pipe removed from the switch then it's a ruptured diaphragm in the switch

 

[rtbcomp]

With the tank empty unscrew the back off the non-return valve and remove the spring and pastille. Check both for damage and examine where the pastille seats in the valve for dirt or damage

 

[gerrymoore]

Sorry...I did mean regulator..silly me!! Thanks for the quick reply..... I think I understand from the diagrams but still a little confused. The replacement regulators on EBAY don't seem to come with the little black pipe...and I can't see how it comes off this regulator to go onto a new one....or am I being thick...or can I buy just a new diaphram?

 

[gerrymoore]

I've just checked the non-return valve..it has got a brand new rubber 'pastille' and both the spring and seating look fine. Happy to buy a new regulator but still wondering about how the 6mm pipe comes off and re-fits to the new?

 

[rtbcomp]

The black pipe isn't normally part of the pressure switch. I haven't seen that sort of connection before, they are usually compression fittings with a nut or push-fit with a release collar.

Ascertain for definite where the air's coming from before buying replacements though.

The purpose of that pipe is to empty the delivery tube (from the pump to the tank) when the motor stops. The NRV stops air coming out of the tank and the other end of the black pipe connects to a valve which is opened by the switch mechanism when it switches the motor off. Hence the short blast of air when the pump stops.

Can you disconnect the black pipe from the NRV and then see where the air comes from?

 

[rtbcomp]

I'm assuming you are getting air leaking when the pump has stopped and not only whilst it's running?

 

[gerrymoore]

OK thanks RTB for the advice. I need to change the 13amp plug for a 20amp and then put the regulator back on...I'll have a go tomorrow and see what's happening...I'll get back with the results.

 

[gerrymoore]

Thanks Mr F ....I've bit the bullet and ordered a new unit....with luck should fix the problem..won't be here until next week so I'll post then...

 

[gerrymoore]

An update..... I've fitted a brand new regulator and removed the little pipe that unloads the pump output. No air leaks now but that hasn't sorted the problem. The motor is running very slowly (900 rpm) and even with a small amount of pressure in the tank the motor stalls when trying to start it again.

I was told that new capacitors had been fitted so I have ruled them out...I have very little knowledge of this type of motor but, reading up and looking at youtube, I have narrowed it down to being either a duff motor , or something to do with the centrifugal start switch (if it has one??)

I've made a short video ...you should be able to view it here

Any help welcomed....

 

[Luke]

When you say you have removed the unloading pipe, what have you done with it?

That and the one way valve are intended to allow the pump to start against pressure in the tank.

It doesn't look like there is much pressure in the tank yet, so this probably isn't critical at this stage.

Does the motor come up to speed with the belt removed?

Is the compressor running free?

 

[rtbcomp]

^^ That pipe MUST be connected between the non-return valve and the pressure switch.

 

[gerrymoore]

OK...I've replaced the 6mm pipe and got the 'hiss' when I turn the motor off but still not running correctly. Took the belt off and the motor run up to about 1000rpm and then suddenly went up to full speed. Tried this a few times and then the motor seemed to go to full speed every time. Put the belt back on and it's struggling around 1000 rpm again. The pump is very free to turn by hand apart from the compression stroke which is harder but I presume this is normal? Does this motor have a centrifugal switch? How can I test the caps?

 

[normspanners]

A decent meter will test caps BUT not always give you the exact diagnosis changing them is the best IMO coz they do get 'tired'

If ya need a little help Gerry giz a call, it might have cap start cap run... cancel that, just watched the vid it has cap start/ cap run coz it has two caps, and the motor is laboured by the sound of it so it may be the run cap that is fault.

 

[gerrymoore]

Thanks Norm..the guy I bought it off said that the caps had been changed but one of them looks new and the other doesn't? Any idea how I know which one is the run cap?

 

[normspanners]

Thanks Norm..the guy I bought it off said that the caps had been changed but one of them looks new and the other doesn't? Any idea how I know which one is the run cap?

the small value of the two is usually the run cap it might range from 3---50 uf the start cap can be up to 500mf or uf

 

[rtbcomp]

As a bit of a long shot, is there any oil in the pump and is it the right sort?

 

[normspanners]

I did one a few days ago and didnt have or could get the cap immediately and my mate needed his lift working so used two caps together to get the motor to go, I have a range of caps here if you need to test they dont have to be EXACT near enough will usually work ... short term
some motors have one cap 'unit' or 'can' with two caps built in.

 

[normspanners]

As a bit of a long shot, is there any oil in the pump and is it the right sort?

The motor is laboured with the belt off and isnt reaching sycro speed IMO

 

[rtbcomp]

Ok - I though he said it ran at full speed with the belt off.