Thread: Fixing an air compressor! Is it worth it!

That's a good catch Bob. I'm going to look at the specs CF (displacement) vs CFM free air a little closer now.

I take it tool makers advertise CFM requirement and compressor sellers plug the pump displacement?
Seems a little cheeky really...

http://www.engineeringtoolbox.com/ra...ors-d_848.html

I found the fault and a few leaks thanks to the soap and water trick!

It ended up being the copper pipe from the head to the tank/pressure switch tee.

I snapped off at the odd looking flare. Kind of like an integrated olive top hat looking thing.

I'm just going to flare it with a punch as it's an odd size (10mm O.D.) and use gasket silicone or Teflon tape and tighten it all back up.
I can't see another fix other than taking it to pirtek to see what they have. It's not high pressure but they may have some brake fittings that fit....maybe?

Originally Posted by Ben Dono

I'm glad I posted up the question! I'm surprised at so many responses.

Thanks PDW, sandblasting was one of the other things I wanted to have a crack at!
Would a 13cfm handle blasting medium sized jobs.....say a motorbike frame or cast iron garden furniture. (Not that I have plans to do either, they were the first type of sandblasting jobs that popped into my head!)

I'm looking at the toolex/airmac t20 with a 120L tank.....maybe the 70L as a lot of the time it's used as a duster! I can always rig up an auxiliary tank for the bigger jobs. I don't think airmac is Aussie...I might keep looking!

Hi Ben,
My 30 year old air compressor on which I have just replaced the motor was an Airmac with Clisby V heads.3o years ago it was Australian. The sticker had a Brisbane phone number.

If today's Airmac is still Aussie i don't know.

Grahame

Airmac is a Glenco brand

sold under a lot of different name

company details :
http://glencomfg.com.au/

I've been looking at compressors for a while and have just been to look at used 3P, 70L, 4HP 4 cylinder Clisby that looks like it is is in good condition AND most importantly it fits inside my existing compressor enclosure with mm to spare, so I have decided to buy it.

It's only marginally less than the price of a new, reasonable quality, single phase, 3HP, unit, but given the current owner (who is a sparky) has fitted a new 3P plug and cable, new pressure switch, new rugged fluid filled guage and new belts I reckon the Clisby will provide better performance and outlast a new single phase unit.

Pick up is tomorrow.

Originally Posted by Ben Dono

I found the fault and a few leaks thanks to the soap and water trick!

It ended up being the copper pipe from the head to the tank/pressure switch tee.

I snapped off at the odd looking flare. Kind of like an integrated olive top hat looking thing.

I'm just going to flare it with a punch as it's an odd size (10mm O.D.) and use gasket silicone or Teflon tape and tighten it all back up.
I can't see another fix other than taking it to pirtek to see what they have. It's not high pressure but they may have some brake fittings that fit....maybe?

Those pipes on rock bottom price units do not have proper connections conforming to any standard. They are made of extremely thin walled copper and are not easy to fix in a reliable way. Keep in mind this pipe is subject to vibrations. And it can get fairly hot in operation, if you use silicone sealant it would have to be high temperature stuff, and it will have to withstand about 7 bar pressure. I think the best bet would be to use a new copper pipe, and to buy or make proper connections.

Originally Posted by Ben Dono

I'm just going to flare it with a punch as it's an odd size (10mm O.D.) and use gasket silicone or Teflon tape and tighten it all back up.

If you do this it might be a good idea to anneal it first. It may have failed due to work-hardening from vibration. Just heat the end of the pipe till it glows and let it cool or quench, doesn't matter. Do this in a not-too-bright place so you can see the glow.

CBA your right! Most of the time you get what you paid for.. Given it's age and use, I'm pretty impressed with it. Considering I'm starting to get disappointed with some of the high end brands I'm having problems with at the moment..... Milwaulkee ya dropped the ball!

If I go to town sometime next week I will pick up some fittings and copper to suit. I'm thinking I will be needing it before then so a bushmans fix might be in order.

I don't know the running temp but it has a heat sink coil around it so it's going to get hot. Silicone has a high working temp but I have some head gasket silicone which has a slightly higher working temp.....or Teflon tape...which ever is higher.

Bryan I did think about it as a fatigue issue. It's a good point mate, I will hit it with a torch before I flare it.

Originally Posted by Ben Dono

CBA your right! Most of the time you get what you paid for.. Given it's age and use, I'm pretty impressed with it. Considering I'm starting to get disappointed with some of the high end brands I'm having problems with at the moment..... Milwaulkee ya dropped the ball!

If I go to town sometime next week I will pick up some fittings and copper to suit. I'm thinking I will be needing it before then so a bushmans fix might be in order.

I don't know the running temp but it has a heat sink coil around it so it's going to get hot. Silicone has a high working temp but I have some head gasket silicone which has a slightly higher working temp.....or Teflon tape...which ever is higher.

HT silicone is OK to around 210º.
Depending on the type of teflon used, it can go a bit higher but it goes soft and flows at around 200º. When Teflon gets too hot it decomposes and releases some nasty stuff. I reckon the compressor connections might get hotter than that.

The other problem with silicone is that it is difficult to get a lasting seal (e.g. the gap between the tiles and a bath). The surfaces have to be scrupulously clean to start with and then any oil around the place seems to creep under the seal.

FWIW contrary to popular perception silicone is it is not gas tight especially under pressure although amount of air loss won't worry a compressor. However it cannot be used in critical situations as we found out at at work when tried to use it to seal a (poorly fitting) SS line running HCl gas from an HCl gas bottle.

My bro in law had exactly the same fitting break on a cheap compressor he was given.

Non standard fitting.

Maybe just use a small torch and solder it together.

I've used solder to join air fittings plenty of times, and provided you get at least about 5 mm internal overlap it will hold pressure at 120 psi no problem.

Rob

Originally Posted by nearnexus

My bro in law had exactly the same fitting break on a cheap compressor he was given.

Non standard fitting.

Maybe just use a small torch and solder it together.

I've used solder to join air fittings plenty of times, and provided you get at least about 5 mm internal overlap it will hold pressure at 120 psi no problem.

Rob

you live dangerously Rob

Originally Posted by eskimo

you live dangerously Rob

Not really.

It takes a lot of force to break two sleeved together small diameter tubes correctly soldered together.

Obviously not suited to bigger diameter jobs, but for 1/4" application it works OK.

It's also worth considering that an average air compressor cuts out at 120 psi.

In comparison your household mains water supply generally delivers at 130 - 140 psi. People have plastic connectors on their watering systems/watering wands etc and they hold up OK even when closed off.

So, materials we may think of as being inherently weak, when compared to other products, can actually be capable of withstanding considerable pressure if correctly designed/applied.

Rob

More to fix now! The elbow out of the head was cracked as well!

Need a rethink on it now but will head into coffs next week and see what's common for 10mm copper tube and the unknown thread on the compressor. I think it's a NPT style thread system but I could never make heads nor tails of that system. It's .65 and a between 18 and 20tpi

I might look at plumbing compression fittings with copper olives. 10mm copper is common in the UK but can't say I have seen it here in OZ. It's too big for brake lines... Maybe a standard aircon size?

I might braze weld the olives in place to overcome the vibration issue...
Will have to wait and see who has what in coffs!