Are old compressors worth rescuing?

[rogerwilco]

I know not much about compressors, but I know you generally want a big tank and lots of power if you want to spray. And that gets expensive.

I picked up a old 16 CFM belt drive unit branded Airboss. I'd guess about 30 years old. Stonking great big tank on it. But in pretty poor condish.

But, I got it for less than $100 bucks, and it was good enough to spray a couple projects (not particularly well, but it got the job done), And it runs my nailers no problem.

Here's the thing. It's enormous. And it's somewhat a miracle it works at all. Guages are all knackered (have to knock em just the right way to unstuck the dials), it's leaky AF (I think from the regulator), weathered, rusty, noisy, and I can hear it's full of water too (but doesn't have a drain valve). Motor seems strong, and it has oil in it.

It's too big a job for me to restore, and it owes me nothing. I'm going to guess it's a $500+ job at the repair shop, including parts labour.

So, is it worth trying to resurrect it? Or leave it be and buy something else?

If I'm honest, a basic compact unit would suit me better. I don't think I need to spray finishes often. But of course I'd like the option to spray too!

[riverbuilder]

I’ve got a couple of theseSydney Tools and they are really good. Super quiet and have done plenty of spraying and they run guns all day, recommended.

[Chris Parks]

I would be surprised if there is not an entry in the bottom of the tank for a drain valve which may have begun to leak or broken and been removed. If it pumps air I doubt I would give it some TLC as a new equivalent one is likely to cost a fair bit of money. I had one that was over 50 years old and it still pumped air and that had a Ford Model A piston in it.

[BobL]

Once compressor air receivers accumulate a substantial amount of water in the tank the compressor will be constantly starting and stopping - is it doing this?

The other concern regarding a receiver being full of water for some time is corrosion. If you can get the water out, I'd recommend an inspection with an inspection camera. If there are lots of rust flakes then I would replace the receiver.

[Chris Parks]

I have had experience with two compressors that rusted to the point of failure and both were a non event with pin holes becoming the leak points. Some compressors also have inspection access through a large screw in plug but that is generally only on larger ones. Me, I would get the water out of it and install a drain valve, replace the gauges and be a happy compressor owner. Instead of screwing the drain valve directly into the tank put a piece of pipe or airline into the tank and then the drain valve into that and any water will drop into the pipe and not stay in the tank.

[rogerwilco]

Some compressors also have inspection access through a large screw in plug but that is generally only on larger ones.

Yep, mine has this. 22mm threaded plug on bottom of the tank. I'll see if I can drain it.

Me, I would get the water out of it and install a drain valve, replace the gauges and be a happy compressor owner.

I'm definitely thinking about it... But it doesn't really solve the size and noise issues. I don't really want to be in a spot where I spend money on something that I end up replacing in the future anyway.

[rogerwilco]

Once compressor air receivers accumulate a substantial amount of water in the tank the compressor will be constantly starting and stopping - is it doing this?

Not really. It cycles probably once every 30-45 mins if not in use. Obviously faster cycles if I'm spraying, or shooting a lot of nails from a big framing nailer.
I can hear it leaking though. An audible hiss. It doesn't sound crazy-fast, but it's definitely there.

[old1955]

I had dramas getting down on the floor and trying to see and feel the brass sump plug in my old Puma 15 CFM. Went and got some brass fittings and came up with this idea which is foot operated.

[BobL]

Use some dishwashing detergent in a cup of water and a small paintbrush to paint joints and look for bubbles. It sounds like is doesn’t have much water in it.

An easy way to vent water from a tank is to plumb in an old retic solenoid and 24V transformer. Saves getting down on the floor to open/close a tap. This means you’ll vent it more often. I had this setup for many years on my old shed. At one point I had it rigged so it auto vented when I turned the compressor off.

FWIW my more recent reticulated compressed air system has about 20m of pipe and is on about 12 hours a day so uses multiple water removal components including a 3m long segment of finned copper coil, a desiccator trap, and a 3 auto water venting solenoids under microprocessor control that open for 50ms every 50 minutes. Definitely overkill for most shed

[Chris Parks]

The large plug on the end of the tank is for inspection purposes. This is a sprung loaded drain valve from a truck tank and the cable can go anywhere convenient, draining the tank then becomes very easy. I have had two auto drains from Ebay and they have both failed after a short time.

AIR TANK DRAIN VALVE & CABLE - 1/4 NPT | Truck and Trailer Spares (trucktrailerspares.com.au)

[BobL]

The large plug on the end of the tank is for inspection purposes. This is a sprung loaded drain valve from a truck tank and the cable can go anywhere convenient, draining the tank then becomes very easy. I have had two auto drains from Ebay and they have both failed after a short time.

AIR TANK DRAIN VALVE & CABLE - 1/4 NPT | Truck and Trailer Spares (trucktrailerspares.com.au)

The Auto vent valves from ebay like these,
220V 1/2inch Electronic Timed 2way Air Compressor Gas Tank Automatic Drain Valve | eBay
These have their electronics too close to their vent point so water coming out of the vent can get into the electronics which eventually kills them.
The first one I had lasted about 2 years so when I replaced it I extended the outlet by about 250mm with some clear PVC tubing and that was still going about 3 years later when I replaced it with 3 industrial solenoids for which the exhaust timing and delay control is done via a microprocessor.

[rogerwilco]

Total change of plan!

I took 10 minutes to actually inspect it properly. Everything was a bit loosey goosey. After cinching up all the connections, it was very easy to isolate the problem. It's leaking outta the regulator. Like, literally pissing air straight outta the face of the broken gauge cover. Clamping the housing together with my hands or reducing the pressure improves it. This is obviously the main leak, and it's dead easy to fix.

I drained the tank. Maybe 500mls came out. Little bit mucky, but really not as bad as I expected.
Check-valve I assume is seems fine, and even the tank gauge that I thought was broken seems ok. It's reading ~130psi at full tank pressure.

So I think I'll put a new regulator on it, install a quick release drain plug, some new rubber feet, shove it under a bench and call it day. Save a few bucks, and I'll feel better about spending the money to replace it when the time comes.

[Boringgeoff]

The truck I used to own had automatic drain valves on it's air tanks. In the very humid conditions of the Pilbara they were useless so I replaced them with brass valves. At the end of the day I'd open them up and go home, next morning I'd fire the truck up and close them after the engine had been running for a minute or so.
Cheers,
Geoff.

[AndrewOC]

I have rashly accumulated a bunch of old air compressors (accumulated accumulators?), when an engineering friend pointed out their explosive potential...
He comes from a 'money is no obstacle' background (big engineering), where pressure vessels can be considered 'consumables'. As a compromise to this school of thought, I like to share this Keith Rucker video- diy "Hydro Pressure testing a air compressor tank";
Hydro Pressure Testing a Air Compressor Tank - YouTube

Seems legit!

A.