Compressor Moisture Issues

Don,

Neat little set up you have there.   Also very doable since I keep my 7 gal tank in the apartment as well.

I have a Harbor freight not too far from home as well.    They are great source for these types of items.

There seems to be a great deal of info/reviews out there on many brands of small compressors.    I did my homework on this.   I saw the Grex demo at the 2010 Mosquitocon and it really impressed me.   The reviews were good as well.    

I do have a monster 25 gal/ 5 hp compressor at my mother's house.   Someday I intend to pipe the air in to my "future" shop from it.   Once that setup is established, I can really fine tune the entire operation.    But for now this will have to do for the apartment.

By the way,   I have a 1/8" female quick connector attached to each of my air sources.   The male is attached to my Passhe hose.    I love being able to switch between air sources in an instant.    These are made by Foster and are only about $5.00 ea.  direct from them.     I use model #2302.

 http://www.couplers.com/images/catalog/page3.pdf

Thanks!

Jack

Install an inline filter and go for it.  Place the compressor where there is good air circulation.  If it does what you want, great.  If it dies, it dies.  If you want to be creative, put some pipe between the compressor head and the regulator.  This would not only cool down the air, but also conduct some of the heat away from the compressor.

I have a little 1/8 hp diaphragm compressor hooked up to a regulator / separator like yours.  I've only had a moisture problem once.  It was after extended use on a warm day and the humidity was 70%, which is unusual where I live.  The head was hot to the touch.  As a precaution, I've added a short section of metal pipe between the compressor and regulator.  The pipe gets warm, so it's doing its job.  The next time I'm at Harbor Freight, I'm going to pick up one of their $3 inline filters.  I don't have air conditioning in my shop.

Don

All good suggestions but I am very limited with my options since I live in apartment above my landlord.   I do use a 7 gallon portable tank for late night silent spraying.   I break out the Grex unit for quieter, longer session spraying when he is home.  But When the coast is clear I break out the Intermatic Speedy for the grunt work.    All of this is an interim solution to my present living quarters.    When I am in my own house, (soon hopefully) I am setting up a much more efficient air feed system.     Very much along the lines of your suggestion.     

Thanks!

Not sure what to feel at this point.   Grex was quite thorough in their reply and even to the time to research my older compressor which I used in comparison.    They left the door open with me so at this point, I will install another filter in line and see what I gain.    Also, I bought this on ebay,  so while it was unused, it was sold as a damaged unit since the fitting that connects the regulator to the head was broken.    The unit is pristine otherwise.   I replaced the fitting and that was that.    There is nothing to indicate any mechanical defect that I can detect.

If there is a design flaw, then I'll have to live with it I guess.   I only bought this because I got it far less than the new price.   But, It is ebay and there are always risks.    I don't think it's a lemon but who knows.

I uses this unit only when it's later at night due to the low noise level.  Otherwise I use my old Inermatic Speedy workhorse.     

Thanks for the input!

Warbirdbuilder

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.

Thanks to all for your input on this! 

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.)

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.  

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.

Eirc

Don,

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.

Thanks to all for your input on this!

Happy modelling!

Don Wheeler

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.

Don

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.

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.

Don

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.

Like it very much otherwise!

Lain,

Haven't tried the in line yet although I do intend to.    Sent Grex an email this AM.  Still awaiting response.

Thanks!

Warbirdbuilder

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.

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.

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.

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.

Thanks,

Warbirdbuilder

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.

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.

Warbirdbuilder

   Please elaborate on the heat  exchanger idea. I am not familiar with them for this application.

Thanks,

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.

Don

Gerald,

Good idea.   I am not sure about the warranty part though as I won this on ebay.    I will make contact with them though.

Thanks!

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!

Don,

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.

Thanks,

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.

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.

Don

Does it have a reservoir? If so is it smaller? That might account for the more moisture in the line, it isn't accumulating in the reservoir.

Also, what part of the world are you in? I know here in South Texas it has been VERY humid lately and that could be an issue.