Hello, I was wondering if any one could provide input on the following. I recently purchased a Grex air brush compressor with the auto on of feature. I bought this model after seeing it at the Mosquitocon 2010 show. Truly much quieter thant other compressors as advertised, However, I have been getting alot of moisture in the line in what I feel is a fairly short amount of run time. It comes with the moisture trap attached at the compressor. ( I know this is incorrect but that’s how all these units are made), I have an old Intermatic Speedy compressor which has no trap and very rairly gets moisture unless run on and on for extended periods.
It could be that it runs hotter than your old compressor. The moisture trap only works if the moisture has condensed back to liquid. Any moisture that is still in vapor form will pass right through and condense further down the hose or in your nice cool airbrush. You may need another trap nearer the brush. Some people put a heat exchanger between the pump and the regulator / moisture separator to cool the air.
The unit is as shown here. I do see some moisture in the reservoir. I live in Northern NJ. It has been more humid and the temps are unseasonably warmer @ about 75 degrees this month.
I do feel that it gets hotter faster than the old unit. I didn’t expect this to be the case since it has the auto on/off feature. I have contemplated using a unit like shown below. Please elaborate on the heat exchanger idea. I am not familiar with them for this application.
The more efficient the compressor the better job it does at squeezing water out of the air. You might want to ask Grex your questions, they are a good group of folks to work with. Drop them an email, include your model number and your concerns…let them and your warranty work for you!
I’ve seen this on home brew jobs where they have cobbled together a compressor, tank and regulator. It can be something like a small radiator or even a coil of copper tubing. The idea is to cool the air down so the moisture will condense when it hits the separator. Your inline unit should take care of your problem. But, I agree, you should contact Grex and see what they have to say.
A properly functioning compressor should not have the type of moisture you mentioned. Touch the cylinder head after the compressor ran for half an hour. If it is too hot to keep your hand on it, the compressor is likely to be defective. Send it in for repair or replacement.
Moisture cummulates when the air gets too hot and then cool down.
When you receive the properly working compressor back, you may consider adding a 25-feet flexible hose, Iwata style. Remove the regulator/filter from the compressor and insert the hose between them. A 25’ plastic hose with connectors from Harbor Freight for $5 will work just fine.
Wouldn’t have thought there was a mechanical issue since it runs smoothly. But, I will run this by the people at Grex and see what they say. Since this was an ebay purchase, I don’'t know if they will warranty it or not. We’ll see. I’ll let you know what they say.
Have you tried placing a moisture trap in-line? By this I mean tank-seperater-hose-seperater-hose-airbrush? You should not be having this issue and I would take it up with GREX but an in-line moisture trap may help.
This may seem obvious, but are you emptying the reservoir when you see moisture in it? It should unscrew at the bottom to allow it to drain. The last time I had any moisture issues in the line was when I noticed moisture had built up in the reservoir…emptying it took care of that, and then I added an inline trap. Those need to be drained occasionally as well.
Ditto on getting an inline trap, and put it as close to where the hose connects to the AB as possible and practical. I believe there are some models that even connect directly to the hose connector on the AB, although some people feel this adversely affects the balance of the AB when holding it.
Yes I empty it as best as possible but moisture/condensation does remain on the bronze filter and the clear bowl. Will be getting the inline soon. Not sure about where I will mount it yet though.
Hopefully Grex will shed some light on this.
Would really like to feel good about this compressor.
The more you compress air, the hotter it gets. It could be that the new compressor just has a higher compression ratio, which is a good thing. But it also means that the air entering the regulator / moisture separator (which is connected directly to the compressor outlet) will be hotter. This then means that after running a while on a humid day, some moisture will get through. I doubt that anything is wrong with the compressor.
I’m inclined to agree with this about the compressor running hot. The one I have, while not a top-of-the-line brand model, tends to run pretty hot after a while and it’s been running for 3 years or so now with no obvious signs of imminent failure.
Got a very prompt and reassuring response from Raymond at Grex. Looks like the machine is OK! It is running hotter due to the higher compression as you stated. It is a piston type and not a diaphram as is my old Intermatic Speedy. That is likely why I don’t experience the moisture issue as much with the old unit. It has thermal protection so there should be no concern of the heat. Raymond also mentioned using an inline filter and longer hose as well. Glad to here the unit is in order.
Yikes. I would think that a decent compressor with an air tank would be almost fool proof. My Senco with a 1 gallon tank almost never has any moisture in it when I remember to check. I also have a Iwata knock off from China that claims to a very small tank (who knows) but I bought a Paasche air hose with a moisture filter built in and it seem to work fine. You can buy the filter along and cut a hose in half and patch it up: wasn’t worth the $10 savings to me. Of course a Paasche air hose works with some brands and not others although there should be some way to make it work at the receiving end.
I noticed there is no reservoir tank on these units. Basically it is on a as needed demand system, which will draw whatever humidity out of the ambient air surrounding it.
Set up the compressor in a dryer area like the furnace room, run your pressure line to your hobby room to a small reservoir tank with a bleed valve at the bottom & your outlet at the top. The air will cool, condensing the moisture there and should be drained (bottom bleed valve) before each session. Attach your moisture trap to the outlet of this reservoir tank, if the hose had moisture in it be sure to dry it completely. Isopropyl alcohol blown through will speed this up or just get a new length of hose.
This set up will have these advantages:
The reservoir will give a steadier pressure as the compressor will only kick in to top it up.
The compressor will not be heard as it is not in the same room!
The moisture will not get past the reservoir tank.
If what Raymond at Grex stated IS TRUE, the Grex compressor (AC-1810A) is a very poorly designed unit. It is an 1/8 HP compressor with maxmium pressure at 60 psi which means relatively low power and low pressure. The 20 L/min is about average for this type of unit. Grex’s claim about “higher compression” making it “run hotter” just does not hold water. A good airbrush compressor should not get hot to the touch and should not have moisture problem in NJ weather.
This is a first post on a Grex compressor at this forum. It does not speak well for them.
I have a made-for-Paasche by Sparmax DA400 compressor. It is a twin piston, 1/6 HP unit that operates between 60-90 psi (auto on-off). The piston head never get too hot to the touch and I never had moisture problem after running long sessions in the midwest. (Well, I have to admit that I have AC on all the time during the summer.)
