Clean & Dry Compressed Air - Very Important

Important information to prevent common issues faced by many getting started in cnc plasma cutting.
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Pspider Support
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Joined: Tue Jul 22, 2008 3:26 pm

Clean & Dry Compressed Air - Very Important

Post by Pspider Support » Wed Jun 10, 2020 12:42 pm

Many of the common problems faced by those getting started are a result of the compressed air supply delivering contaminated air to your plasma cutter. When this happens the plasma arc will incinerate the contaminants, the arc will become unstable and burn much hotter. This condition will destroy your torch consumables quickly if not immediately and you will never achieve a quality cut. Not only does this destroy expensive consumables and produce poor cut quality, it also contaminates your torch lead assembly. We hear the following all the time from new operators:

"I just put in a new set of consumables so that can't be the problem"

Consumables can be damaged or destroyed on the very first pierce with contaminated air.

"I bought a filter at Home Depot so that can't be the problem"

Common hardware store air filters will remove some particulate and moisture but typically are small capacity and only effective for a short period of time. Fine for air tools but not for your plasma cutter.


If you are following the manufacturers cut charts and not achieving smooth, clean cuts with minimal dross, the first place I would look is at your air supply. Signs that your air is contaminated with compressor oil, water, particulate, etc. are black and/or grey stains inside your nozzle deposited in swirling pattern towards the hole in the center. These same swirling stains will likely be found around the main body of your electrode. These are deposits from the contamination burning up inside the nozzle.

A 1 micron filter element will be effective in removing raw water, oil vapor, and fine contaminates and deliver much cleaner air. Adding a larger 3-5 micron filter in front of your fine 1 micron filter will dramatically extend the life of your 1 micron filter element since the air will have the larger contaminates already removed. After filtering the air you will need an air dryer to eliminate humidity in the air supply before delivering it to your plasma cutter. The 2 most common air dryers used for this purpose are desiccant dryers and refrigerated dryers.

Desiccant Dryers
Desiccant dryers are affordable to purchase and have a lower dewpoint than a refrigerated unit which will deliver dryer air, the downside is that the desiccant needs to be dried or replaced once saturated with moisture. The more desiccant your dryer holds, the more moisture it can absorb and you will have to dry it less often. The desiccant filter/dryer unit sold here holds 5lbs of desiccant which typically would need to be dried on a monthly basis depending on humidity and hours of use. Its a good idea to have 2 batches of desiccant for your dryer so one batch can be dried and stored while your using the second batch.

Refrigerated Dryers
Refrigerated dryers require electricity to operate, will cool the compressed air to remove the humidity and are for the most part maintenance free. For shops operating a plasma table all day every day this a good option as you will never have to stop and dry desiccant. Keep in mind a refrigerated dryer will still require that you filter the incoming air to remove oil vapor, raw water, and particulate before the dryer. Refrigerated dryers are very effective but have a higher dewpoint and will not dry the air as much as a desiccant dryer.

Regardless of what type of dryer you choose to use it is important to install it 20' or further from the outlet of your air compressor for best performance. This will allow the hot compressed air to cool before before entering your dryer so your desiccant will last longer and your refrigerated dryer will cool the air to a lower tempurature. Installing dryers with new clean air lines is also a good idea.

A popular all in one filter/dryer is the Sharp 6760 3 stage dryer sold here shop/dryer_sharpe6760.html This 3 stage unit shown below incorporates a 3 micron stage 1 filter, 1 micron stage 2 filter, a desiccant dryer with 5lbs of desiccant capacity, pressure reuglator, ball valve, and fittings.

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For those who choose to use a refrigerated dryer the first 2 filtering stages of the 6760 can be found here shop/filter_sharpe705fc.html This 2 stage unit shown below incorporates a 3 micron stage 1 filter, 1 micron stage 2 filter, pressure reuglator, ball valve, and fittings.

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In addition to filtering and drying the air after the compressor it is important to drain your compressors pressure tank on a regular basis. We suggest starting out every couple days to get an idea of how much water your tank accumulates over time and you can adjust your schedule from there so there is little to no water in your tank at any time. This will prolong the life of your filtering consumables and allow your compressor to operate efficiently. Smaller compressors that run more often will typically generate more heat which will produce more water so get an idea of what you need and set your tank draining schedule.

Good luck and have fun :Yay

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