Effects of moisture on plasma cut???

[Jcar]

I think I'm having problems with moisture in the air system that feeds my plasma table. Typically I have a nice smooth edge. However, tonight I was running a long program and started seeing my edge quality degrade to what I can best explain as something that resembled a rough sawn edge. Does anyone have pictures or a description of the effects of moisture on a plasma cut edge?

Thanks,

[carbidecraters]

Originally Posted by Jcar I think I'm having problems with moisture in the air system that feeds my plasma table. Typically I have a nice smooth edge. However, tonight I was running a long program and started seeing my edge quality degrade to what I can best explain as something that resembled a rough sawn edge. Does anyone have pictures or a description of the effects of moisture on a plasma cut edge? Thanks,

I can only tell you my personal experience. Letting moisture through omy system makes the little tip inside get eaten away fast and that little actuator goes out quick as well. The cuts ended up going down in quality and its almost like the plasma searched for the ground...kind of like what you are explaining.

[xjdubber]

its more of a chain reaction, the moisture wears out the consumables quicker and you get a crappy cut quality. Did you actually watch the machine troughout the whole job? Torch height control issues can give you the same problems.

[jimcolt]

Moisture can create a few different issues in a plasma torch. If you are using air as the plasma gas....then it is very likely that you will encounter moisture in the air sooner or later! When operating off an air compressor...the moisture that is present in the ambient air is amplified.

Often, moisture from a compressor carries other forms of foreign material such as oil (from the compressor), rust or other coating from the plumbing....and any other types of particulate that could be in the air near the compressors air intake.

Air plasma torches are designed to use clean, dry, compressed air. Air is roughly 80% nitrogen and 20% oxygen (there are small amounts of other gases present in air)...and the high temperature physics that make the plasma arc work are designed around this gas mix.....when water is added, the water breaks down into it's elements, basically oxygen and hydrogen.....the hydrogen is consumed....but causes issues that can cause rapid wear on the nozzle orifice, and the increased oxygen content causes rapid erosion of the hafnium emmitter (the little silver slug in the end of the electrode) that is the arc attachment point. Most other foreign materials break down into a form of carbob that can cause stray paths for the plasma arc to follow.....eventually shorting out parts of the torch that must be non conductive, such as the swirl ring,retaining cap, and torch body insulation materials.

A little moisture now and then often does not show an immediate effect on cut quality....but over time can damage the torch and the consumables to the point that they must be replaced.

A refrigerated air dryer upstream of the plasma system....sized adequately for the plasma air flow rate is worth its weight in consuamble parts and torch heads! Many use the low cost unit from Harbor Freight with good luck....it is usually less than $350 (US)....and seems to be reliable. There are other units available from Graingers in the $700 to $1000 range.

Jim Colt