Re: Moisture trap for air brush

O Fenton Wells

Gentlemen, I don't want to pick an argument but I would disagree.  Most of the moisture we get in our applications is from the moisture that is compressed with the air.  I don't think given the short distances between our compressors and our air brush the delta T is going to be an issue.  Blow by from the compressor cycle especially given that moistures condenses in the tank is usually the source of moisture in our applications.  If you get a fairly large moisture trap, or pneumatic filter as used in our applications it probably doesn't make much difference where you put it as long as it is in front of, that is before the air brush.  Unless you have a large industrial system the moisture and temperature is not the cause of moisture in most cases.  I put my filter right after the regulator that came with my compressor.  It is slightly oversized for my application but it has never failed me, that is no water has gone to the air brush.  I have used this set up in Florida, Ohio, Illinois, New Hampshire and now North Carolina.
Fenton Wells

On Wed, Feb 12, 2014 at 5:55 PM, <bierglaeser@...> wrote:

When you say "as far down the airline as you can" I assume you mean as far away from the compressor as possible.  That make sense because the air would be ever cooler as it progressed away from the compressor.  The instructions with the trap show it connected to the bottom of the airbrush where the hose normally connects.  That isn't convenient in my case  but possible, of course.

My question, however, was really how far above sea level should it be placed.  What I really mean is, must the moisture trap be below the airbrush?

I am probably unnecessarily concerned about this issue because the humidity is always relatively low here.  We have experienced a sweltering 50% but 20% inside my heated/air-conditioned building is consistent.

Thanks to all who responded.  Based on what has been said, some components will be rearranged.

Gene Green

---In STMFC@...,
Install the trap as far down the airline as you can find a place to fit it. 

Industrial compressors often have after coolers which are intended to lower the temperature of the compressed air;  long pipe runs have a similar effect. Since any moisture in the air compressed will condense as the temperature drops, the trap should be fitted at the outlett of the after cooler or better still at the far end of the fixed line so that any condensation in the lines will also be removed.

If you have a fixed compressor then installing few feet of metal piping between the pump and the moisture trap and making your airbrush hose connection close to the trap would be very a good thing, especially in humid climates. While good units are not cheap,  automatic drain traps are also worth considering if you are running the compressor extensively, especially in damp climates, and these should be fitted at a low point in the piping as this is where the water tends to collect; unless you want a wet patch on the floor in the workshop, don't forget to install a tundish and drain to the outside as the trap will discharge slugs of water at intervals. 

For the person using a small hobby compressor in an apartment with the airbrush attached directly to the compressor, a system like this is probably overkill, but if you are doing a lot of painting and have a tank mounted compressor in a permanent place in a garage or workshop, then a few feet of iron piping and a drain trap might be a good investment


in the line as you can 
On 9/02/2014, at 3:22 PM, <bierglaeser@...> wrote:


Some time back Bill Welch, if memory serves, initiated a discussion that eventually included the pros and cons of including a moisture trap in one's air brush setup.  Although the humidity in my layout building here has been a very consistent 20% and there was never any problem using an air brush sans moisture trap in El Paso, I decided a moisture trap was a good idea.  It arrived today.

As I recall (I can't find the original thread) someone suggested that a moisture trap is best positioned as low as possible.  The obvious and most convenient position for my moisture trap is immediately below my pressure regulator which is positioned outside my spray booth at about the same level as the air brush when it is in use.

Should the "plumbing" be rearranged to locate the moisture trap lower?
Should the moisture trap before the pressure regulator?

Gene Green

Fenton Wells
5 Newberry Lane
Pinehurst NC 28374

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