Air compressor water filter

I bought a 4-gal compressor/18 G Brad nailer combo from RONA today. You may
question my choice but at $130 I did not think I could go wrong.
In addition to nailing brads I intend to use the compressor for painting and
blowing stuff off surfaces (metal chips for the purpose of being on topic).
For the former two choices dry air is recommended and I, therefore, need an
air filter. This is where I am coming un-stuck: There is a bewildering array
of air-filters on the market, starting at $5 and going as far as $220.
No amount of searching provides guidance as to what filter one should get. I
can only infer that as Canadian Tire carry only two, one for $27 and one for
$40, the odds are that one of them will do the job.
The manual states that the filter should be connected between the hose and
the tool but I just cannot see it as practical. Is there a compelling reason
not to connect the filter between the compressor outlet and the hose?
Reply to
Michael Koblic
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You can't compress the water vapor in the air because it's near enough to its triple point that it will condense instead, giving you 100% humidity at the tank's temperature plus liquid water. If the tank is too small to cool the hot air from the pump the warmer air can hold more water.
When a regulator drops the pressure the volume increases and the relative humidity (at ambient temperature) drops, since unlike the air the water vapor wasn't compressed. However the cooling from expansion may condense water droplets.
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The water filter at the tool catches any liquid water that condensed or was blown into the line, if the line stays connected to the tank. IMHO if you normally disconnect the hose it may dry out and a trap at the tank could be adequate.
I've been considering a cheap, high maintenance DIY drier consisting of a coil cooled by ice, a separator and drain, a large pipe filled with Calcium Chloride and a filter.
Reply to
Jim Wilkins
I thought that you shouldn't weld to a pressure vessal.
Reply to
Mike - others have explained, let me add a few things
1. the little compressor will not put out enough air for a full sized paint gun - be sure that whatever you choose uses less air than the compressor puts out - you can run an air brush or a small touch up gun.
2. you need to let the air cool a bit before the filter - a coil of 1/2 inch copper tubing will cool it if the tank doesn't. Larger compressors have a length of tubing with fins on it between the compressor head and the tank - if you add some fins to the tubing on yours that will help a lot.
3. Harbor Freight (and thus presumably Canadian Tire) carry a combo unit that has a coalescing filter, a regulator and an oiler for about $25 US, on sale from time to time for about $18 US. If you employ this and put three outlets on it - one after the filter (for full pressure), one after the regulator (for spray gun) and one after the oiler (for air tools), you will have a proper unit for your little pump.
4. do not use a hose that has been attached to the oiler for painting, ever ever ever. To avoid this, I have hoses permanently attached to my air tools, I connect them to the oiler, never use an extension.
Reply to
Bill Noble
For a conventional plumbed air system, with a large air tank and an oil-crankcase air pump, there is the risk of water or oil vapor reaching the air tool or paint gun nozzle.
Conventional air systems are plumbed with pipe sloping back to the air tank (hotter air from the tank cools in the long lengths of pipe), to minimize the likelyhood of water laying in the piping, and instead of any accumulation of water, it would drain back to the tank, where it would be drained off at regular intervals.
For the conventional air system, there is always a possibility of a small amount of vapor reaching the tool/paint gun. The accessory that effectively removes vapor from the air by trapping it in a bowl (to be drained regularly), was commonly referred to as a water/oil separator. I've done lots of painting with only a water/oil separator (trap), without any problems from moisture or oil affecting the paint.
Many small portable air compressors don't have oil crankcases, but they will likely still have water vapor in the compressed air. A length of air hose laying on a cool concrete floor is similar to the pipe in a conventional air system, in that the hotter air will cool in the hose. A water/oil separator near the tool/paint gun will trap vapor, but won't effectively stop a sudden blast of accumulated water, if that should occur.
Reply to
Someone here added a transmission line cooler with muffin fans to cool the air between the pump and the air compressor receiver:
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It=92s larger than your air compressor, but might be food for thought if you upgrade yours in the future.
Reply to
Denis G.
ooohhhh! Nice idea! Or once could use a heater core from something like a Ford Van..they are rectangular and could hold 2 muffin fans one above the other.
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Reply to
Gunner Asch
Thank you and all the others.
Looks like "suck it and see" (or in this case blow it and see) policy is in order. OTOH I wondered about this gizmo:
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which could be conveniently placed between the tool and the line.
BTW the compressor is oil-less. The tool oiling is achieved by droping oil into the tool inlet. I assume that there is no blow back of this oil to contaminate the line? Considering the frequency with which I will be using the brad nailer I am reluctant to go with anything more elaborate.
As far as "painting" is concerned, airbrush is about the size of it.
Reply to
Michael Koblic
Technically you're probably right, but practically I don't think that it's a big concern in this case. I worry more about corrosion eating the bottom of the tank. That probably also voids the certification of the tank, but few amateurs have the means to measure wall thickness on these things. Good ultrasonic thickness gauges are a bit pricey.
Reply to
Denis G.
Somewhere in my spare parts I have a new stainless steel core about the size of a heater core. It has a mount for a pair of fans, and was made to cool an industrial laser. I picked it up for $5 about 15 years ago. :)
Reply to
Michael A. Terrell
When my central air system was replaced, I kept the old A coil. Still haven't found the round "TUIT" to check them out and hook them up. Gerry :-)} London, Canada
Reply to
Gerald Miller
A crude solar heater?
Reply to
Michael A. Terrell

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