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Air compressor is losing power.

Not pumping enough air.

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Brian John23/07/2016 07:48:35
1441 forum posts
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This air compressor has worked fine for about three years but it is now losing power and barely pumps enough air to run my airbrush let alone my steam engines. Before I go opening up this air compressor can somebody tell me what the problem might be and what I should be looking for ?

air compressor 1.jpg

JasonB23/07/2016 08:19:52
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Is there a filter in that regulator/trap? could be blocked. Next I'd take the whole thing off the compressor and see how it runs before looking deeper inside for things like a split diaphram

Clive Foster23/07/2016 08:20:30
1700 forum posts
46 photos

First port of call with this sort of problem is the one way valves in inlet and outlet ports. If either is damaged, worn or has dirt on the seat you will have a leak and the compressor will just push air backwards and forwards through the leaky valve instead of compressing it. If yours has a pressure release valve to prevent over pressuring that can also leak. Usual symptoms of a leaky pressure release valve is low pressure rather than near complete failure. Not all compressors of this type have a release valve though. With low output compressors like these you only need avery small leak to seriously reduce efficiency. After all its only intended to supply the very small nozzle on an airbrush.

Worst case scenario is split or distorted diaphragm which will probably scrap the compressor. Spares can be hard to find, especially if its an economy range one.

Clive

Ian S C23/07/2016 09:58:50
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Brian, I suppose that you drain the water out of the tank often, probably every time you use it at your place. I emptied about a bucket full of bright yellow water from a friends compressor.

Ian S C

Brian John23/07/2016 10:28:04
1441 forum posts
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Do you mean the clear plastic case ? Water builds up in there during summer when it is VERY humid but I always drain it before and after using. It never seems to be a problem during winter...or what passes for winter here.

Edited By Brian John on 23/07/2016 10:28:43

Howard Lewis23/07/2016 11:15:56
1917 forum posts
2 photos

Daft question: The air line , being small isn't blocked is it?

All good advice, and worth following through in a logical sequence, (I would suggest start at the end of the Delivery pipe, and work back towards the reservoir, with a check on the diaphram as the final. With regard to the reservoir (tank) , (not the clear plastic condensate separator, which should also be drained regularly), the condensate should be drained out after every use, and the drain valve left open until next required for use.

Often these pressure regulator/ condensate traps contain a metal filter. If you have not drained the condensate from the reservoir, and the plastic bowl, regularly, this could be corroded/blocked! If you can, carefully clean it. If it looks like a load of brass rods bundled together, you may need to soak it in something like vinegar to get rid of the corrosion, before washing it with hot water, reinstalling, and then blowing air through it to dry it, keeping the reservoir pressure as low as possible to minimise condensation taking place.

When you drain the tank, leave the valve open for several minutes, it is possible that the condensate may freeze, in the drain tap and the draining cease for a while. It will then restart, probably accompanied by small pieces of ice flying about.

Like your lathe, you will eventually overcome the problem!

Howard

JasonB23/07/2016 11:35:25
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Brian, you don't have a tank so no need to worry about that

Howard Lewis23/07/2016 11:45:54
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Jason, it looks from the photo as if the diaphram compressor mounts on and feeds into the cylindrical part, which I am sure is a reservoir, albeit one of only a few litres capacity.

Howard

AndyP23/07/2016 11:48:44
188 forum posts
30 photos

I use exactly the same compressor to drive my wax injector and it has no reservoir other than the condensate trap.

Andy

JasonB23/07/2016 13:23:39
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The right hand 2/3rds are motor and the piston and crank take up the rest of the space to the left. The cooling slots in teh lower halves between the feet would tend to let any air out if it were a tankwink 2

Neil Wyatt23/07/2016 14:03:14
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I have an older but basically the same compressor; I use an external reservoir from an old aluminium fire extinguisher rated at least ten times the compressors maximum pressure (it stalls above 30psi). For a small spray gun/airbrush the supply pipe is meant to be sufficient as a reservoir but for small steam engines the reservoir makes it easier to set a steady low pressure with a bleed valve.

Neil

mgnbuk23/07/2016 17:31:13
506 forum posts
10 photos

This is not necessarily a diaphragm compressor - a lot of these small airbrush compressors use wobbling pistons, with the inlet valve in the piston crown & the inlet air drawn through the motor housing, cooling the windings - hence no visible inlet port in the head.

**LINK**

Most likely culprits would be a stuck / failed valve, excessively worn / failed piston seal or worn/damaged bore.

My airbrush compressor is similar to this, but is mounted on a 3 litre receiver - the pholograph seems to show the basic compressor sat on a chair.

Nigel B.

Michael Gilligan23/07/2016 18:38:29
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Posted by Nigel B on 23/07/2016 17:31:13:

This is not necessarily a diaphragm compressor - a lot of these small airbrush compressors use wobbling pistons, with the inlet valve in the piston crown & the inlet air drawn through the motor housing, cooling the windings - hence no visible inlet port in the head.

**LINK**

.

Very interesting, Nigel ... Thanks for linking the patent yes

[Brian] : There's only one way now ... "Off with its Head"

MichaelG.

Michael Gilligan23/07/2016 19:18:11
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13053 forum posts
570 photos

At your own risk:

Disposable Helium tanks show great promise as low-ish pressure air receivers

http://www.click4balloons.co.uk/f50-helium-tank---large-disposable-helium-gas-cylinder-15479-p.asp?gclid=CO7h4fGXis4CFYXGGwodhGMHvQ

The instructions clearly state that they must not be refilled, BUT that relates to highly pressurised helium, doesn't it.

MichaelG.

Edited By Michael Gilligan on 23/07/2016 19:19:27

Howard Lewis23/07/2016 20:24:19
1917 forum posts
2 photos

If anyone wants one, I have one which can be collected from Peterborough. (UK)

The connecting thread is 12 x 1mm

Howard

Neil Wyatt24/07/2016 08:59:35
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Posted by Nigel B on 23/07/2016 17:31:13:

This is not necessarily a diaphragm compressor - a lot of these small airbrush compressors use wobbling pistons, with the inlet valve in the piston crown & the inlet air drawn through the motor housing, cooling the windings - hence no visible inlet port in the head.

Every diagram I can find shows two ports in the head. Mine has a reed valve in the head, and my recollection is that there is a second on top of the broad, thin 'piston' attached to the diaphragm, so a diaphragm and only one valve in the head.

Neil

JasonB24/07/2016 10:03:19
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Just another thought Brian, have you inadvertantly turned the regulator knob as this will restrict the output.

It's the knob above the red ring.

Brian John24/07/2016 10:44:53
1441 forum posts
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I use that knob all the time to adjust the airflow for my airbrush. At the moment it does not seem to be doing anything at all. I might have a look at that first before I go pulling anything else apart.

Ian S C24/07/2016 12:13:13
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Oops, I did not see the photo of your compressor before I posted, you have a water trap, and no tank, or is that a tank that it stands on? I'd be looking for leaks in the diaphragm, and the pressure regulator, or even the drain valve on the water trap. Another place to look is the eccentric, and the rod connecting the motor to the diaphragm.

Ian S C

JasonB24/07/2016 12:52:08
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As I said earler just unscrew the whole regulator/trap assembly from the compressor and see how it runs this will eliminate faults in the regulator and blocked filter before you start delving deeper into the unknown

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