Atlas Copco Compressor problem

[Gary900r]

The rectangular finned unit on the side of the compressor with the 3 pipes is the non return valve. If you disconnect the pipes and remove it from the machine you then need to undo the 4 bolts to dismantle the unit. Noting where and which way the springs and valve plates go it is simple to clean all components and check to make sure they are free to move.

 

[rickyn]

The rectangular finned unit on the side of the compressor with the 3 pipes is the non return valve. If you disconnect the pipes and remove it from the machine you then need to undo the 4 bolts to dismantle the unit. Noting where and which way the springs and valve plates go it is simple to clean all components and check to make sure they are free to move.

This wouldnt be Gary H would it ?


Anyway here we go, Took the square finned unit apart, theres very little moving parts inside it.






So cleaned it all up and this just leaves this, the only moving part.




Now the rusty flaky part on top, i cant make out if that ever was something or is just a mushroom of rust, but when removed this is inside and was stuck in one position but other than being stuck to its seat the two sprung steel leaves are in good condition. The seat they press against on one side is pitted with corrosion though.





It not obvious to me how it works or if it should go back in a certain position,or indeed what makes it turn to block the holes ? but i have cleaned it up ready to re assemeble. I take it i cant use grease or anything ?

Is this the non return valve ?

 

[Gary900r]

Yep that's the non return valve.
From memory the rusty part on top should be a thin flat steel disc. The body part above the dish should have holes that line up with the disc. When running pressurised air from the cylinder heads push against the plate and overcome the spring pressure which allows air to enter the receiver. When the machine stops the air pressure in the receiver combined with the spring pressure push the plate against the holes forming a airtight seal.

 

[rickyn]

Thanks Gary, there are no springs in there ? Any idea where i would get a spare for this or and exploded parts diagram.

 

[Gary900r]

Try http://www.angliancompressors.com/ they are Atlas distributors.

 

[Manchecd]

New NRV?

You might find that fitting a new NRV is the best solution if this can be done.

I had similar problems with my old Atlas Copco, with the NRV not working, and with a new one fitted in line it now works fine.

If you want to look at the arrangement on mine, it is on the Forum. See the last page on Atlas Copco problem - please help guys, posted by manchecd on 15/4/2012.

I can dig out the details on where I got the valve from if that would be any use.

Colin

 

[rickyn]

Hi Colin, i have read your thread with interest, i am fairly certain mine needs a non return valve replacing. It seems i cant get one of the type i have fitted so i really have reached a dead end.
I desperately need this working as i have so much blasting to carry out on my projects and my hobby set up just isnt man enough.

In desperation i started looking at a new compressor to replace it, but to but and equivalent modern set up is just way out of my budget.
And in any event i really want to get this fixed as i earnt my living from it for years and would like it once again to take pride of place as a treasured peice of equipment in my workshop.

 

[MattF]

Can't see how that should be too hard to repair, with a bit of patience and testing. With regard a replacement, any non return valve which you can manage to hook into the lines somehow, most likely with threaded adaptors, should do.

 

[rickyn]

Hi Mattf,If i understood it a bit more then pherhaps i would have a chance, i still dont seen how the two leaves of steel sheet seal the air off, theres no springs at all inside there ? I was going to try and fill the worst of the pits in on the seat with chemical metal and then get the surface flatter. But like i say, its so simple but i dont understand how it seals it off ?

 

[MattF]

theres no springs at all inside there ?

That piece in the last photo with the two sprung leaves appears to be the spring.

I was going to try and fill the worst of the pits in on the seat with chemical metal and then get the surface flatter. But like i say, its so simple but i dont understand how it seals it off ?

I'd personally start by cleaning the rust off, (using a copper coin as a scraper will prevent surface damage), then using a washer of some type where that rust ring is, else a flat, solid circular plate with a locating lug which keeps it in place, probably locating into the centre hole. Without knowing exactly what the whole affair looks like internally, those would be my two first trains of thought on how to approach repairing it.

 

[rickyn]

Well i thought it was worth having another look today, so took the nrv off





the seat on one side for the valve is sound




and this portion seems serviceable



Problem is this bit, this is after i cleaned it up.





There doesnt appear to be any rubber washer under it, so i built the surface up with chemical metal, flatted it and refitted it but the problems the same.

The unloader valve starts hissing when it the motor cuts out at full tank pressure, but just keeps on hissing and hissing... to it must be the tank getting past the nrv.

So has anyone seen something that i can either fit to one of the pipes or the tank or the Nrv body. Is there a universal Nrv that i could adapt ?

Any why would Atlas make such a big unit in the first place ?

I really must get it sorted it such a lovely quiet motor when its running, i did find a used motor and Nrv in ebay but it was £580 quid

 

[MattF]

You should be able to shoehorn a standard type in there, with a bit of creative piping.

http://www.google.co.uk/search?hl=e...sor+non+return+valve&btnG=Google+Search&gbv=1

 

[rickyn]

Hi Matt, that takes me to a google image page, would you have a link to the actual part ? I see from the image that its a much simpler affair. Why not just use that type during manufactuer ? Would have saved a bundle i would thing, or is it due to mine being so old ?

 

[rickyn]

Just looking at those images, if i can determine what size my 3 threads are i may be lucky enough to not need any extra pipe work, the inlet and tank threads are the same size, but obviously the unloader outlet is much smaller. I f i can get one that has the same sizes i think i could just conneect the new valve in the area of the old. Just determining what size and threads i have is the difficulty.

 

[brightspark]

Just looking at those images, if i can determine what size my 3 threads are i may be lucky enough to not need any extra pipe work, the inlet and tank threads are the same size, but obviously the unloader outlet is much smaller. I f i can get one that has the same sizes i think i could just conneect the new valve in the area of the old. Just determining what size and threads i have is the difficulty.

more than likely bsp just take the part to a plumbers merchant and try the fittings

 

[MattF]

Hi Matt, that takes me to a google image page, would you have a link to the actual part ?

Just search for 'compressor non return valve'. You'll find links to shedloads of places which sell them, Machinemart being one.

I see from the image that its a much simpler affair. Why not just use that type during manufactuer ? Would have saved a bundle i would thing, or is it due to mine being so old ?

Yours is simply more robust than standard ones, but a standard will do fine.

 

[laserline2]

As mentioned previously in this thread, if when the compressor switches off you can hear hissing for an extended period of time and if you leave it the tank pressure is dropping then yes the NRV is letting past and will need replacing, i personally wouldnt bother messing about with a different version of NRV i would ring your local Atlas Distributor and ask the question