Air Compressor Reviews

Running a Dry Air Compressor

In the next few chapters I will be explaining why running a dry air compressor is important, not only to protect the PneumaticPlus Air compressor water removercompressor itself, but also the air tools you are using, and to protect against contaminants being transferred to the finish of the product being worked on.

Contaminants that can pass down an air line


Due to the fact that dust is found in the natural environment means that when your compressor sucks in air it will also suck in dust. And, even though most air compressors have an intake filter, they cannot stop every particle of dirt from entering the machine.


Oil lubricated machines have a longer life than their oil free counterparts, but there are certain drawbacks, one of the being that oil can enter the air lines, especially when the machine is old or is used on a regular basis causing wear to the oil seals. On the plus side, if contamination is not an issue and you are using the compressor for non critical finishes, such as nailing or sanding, a small amount of oil will actually lubricate the tool.


Understanding why water is present in your air lines will give you an insight into how it got there in the first place, how to remove it, and why running a dry air compressor is so important.

Compressors take in substantial amounts of air and compress it into the tank. Water vapor occurs naturally in the air and gets sucked into the tank along with the air.

The air inside the tank is hotter than the external air due to it being pulled through the inlet tube and compressed into a small space. Hot air contains more water vapor than cold air, and when the air is sent down an air line it will cool, allowing the water vapor to condense into a liquid.

Many of the small and medium jobsite air compressors on the market today have no way of filtering water before it enters the tank. Most do have an air filter that will remove airborne contaminants such as dust and other small particles, however, this is not going to stop all dirt or water from entering the compressor.

PneumaticPlus Air compressor water remover

PneumaticPlus SAU2030M-N02G

Ensuring a Dry Air Compressor by Adding a Water Trap

Some of the static or shop compressors do come with water traps, however, When carrying out tasks such as paint spraying, sandblasting and powder coating, it is imperative that water and dirt is filtered out before it reaches the blaster or spray gun, and it is well worth adding another device as close to the air tool as feasibly possible. Placing the filter or trap away from the compressor will allow the air to cool, enabling the filter to collect more moisture.

 If you have a steel tank compressor ingress of water can rust the inside of the tank. Both rust and water can then be transferred through the system, eventually causing valves to stick and air tools to breakdown prematurely. An Aluminum tank will not rust, but you could still have problems with the transference of water and particles to your air tools.

So, if there is no way of attaching a water trap before the air enters the tank, the only alternative is to drain the tank after each use and add a trap or drier to the tool feed line or lines. At least this will prevent a lot of the moisture from reaching any air tools, prolonging their life and preventing job contamination.

Dry Air Compressor – Driers, Filters and Traps

Refrigeration Air Dryer:

The refrigerated drier is the most effective type of moisture removal device. Similar to an air conditioning unit the refrigerated drier works by cooling the air, removing the water and reheating the air to room temperature before sending it to the air tool. The only drawback is the cost. They start at around $600 and go up into the thousands. However, for a professional setup, the Refrigerated Air Drier may be a worthwhile investment.

Water trap/filters

There are many different makes and models of water traps and filters on the market. Simple models such as the Campbell Hausfeld PA2121 have a filter element that traps dirt particles and removes water. Other models such as the PneumaticPlus SAU2030M-N02G have a double trap and pressure regulator. Overall, these types of traps will remove most dirt and some moisture. Many people use a series of traps to try and maximize the effectiveness, but, each trap on a line will slightly reduce the pressure.

Campbell Hausfeld PA2121 Water Trap

Campbell Hausfeld PA2121 Water Trap

PneumaticPlus Air compressor water remover

PneumaticPlus SAU2030M-N02G

dry air compressor

DeVilbiss 130525 QC3 Desiccant Water Trap

Desiccant Trap

An absorbent trap, such as the DeVilbiss 130525 QC3 above, is filled with a material called desiccant. When air is passed through the desiccant it absorbs the moisture, providing a very effective water removal system. Though, there is one main disadvantage with this system, and that is the fact that the desiccant particles will eventually reach their absorption limit, rendering the filter useless. The desiccant can be replaced or cooked in an oven to dry it out and then be re-used.  Eventually the absorbent desiccant will need to be replaced as it will break down after being cooked a few times.

Portable Air Compressor Water Traps

If the compressor is in a static shop environment the filter/trap can be screwed to a wall or other static object, but what about portable jobsite compressors where the machine needs to be constantly moved around the work area?  Due to their relatively small output the small, portable air compressors don’t have enough CFM output to power tools such as large spray guns and sandblasters, so, job contamination may not be as much of an issue with these types of compressor.

Still, the fact remains that water, dust and air tools do not make a good combination, even if you regularly oil the tool, water can still cause a problem. So, what’s the solution for the portable air compressor users? The answer to running a dry portable air compressor is an in-line filter.

In-line Filters

TEKTON 4755 In-Line Air Compressor Water Trap

TEKTON 4755 In-Line Air Compressor Water Trap

In-line Filters such as the TEKTON 4755 Oil/Water Separator are an ideal solution for portable, jobsite air compressors. They can attach directly to the air tool or between two hoses and are so small and lightweight they don’t tend to get in the way or restrict the use of the tool in any way.

For running nail guns, inflators etc, they are an ideal solution, however,  for such projects such as paint spraying they should always be used as a secondary line of defense and used in conjunction with a main trap.

Running a Dry Air Compressor by Draining the Filters and Tank

Filters do need to be drained on a regular basis, so, get into the habit of draining your tank and filter together. Also, the air compressor intake filter should be changed in line with the manufacturer’s recommendations.

Failing to drain the tank on a regular basis will not only lead to water in the lines, it can also lead to internal rust which will eventually make the tank weaker and can have catastrophic consequences if the tank fails.

The video below demonstrates exactly why you should run a dry air compressor.


Updated: September 21, 2017 — 11:34 am
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