Shop Air Supply Cleaning
Shop Air Supply Cleaning
(OP)
Well now that we finally have close to what we think is a root cause, I figured that I'd aske the compression pros.
Our plant makes thin stamped parts, our customer has alerted us to a problem with residue on the surface of the parts. This residue seems to be compressor oil. Our shop air system is fed with Atlas Copco compressors I think they are screw type. (standard shop air ~100to 120psi)
There is a robot that uses air blowoffs as part of its handling. What are the different levels of fitering I can reccommend to my boss as ways to prevent air from reaching the robot?
(Currently I have some minor experience in asssuring I have clean dry air for the lab. I have had sucess with wilkerson using a 5micron dryer/filter followed by a .5micron oil coalescing filter.)
Nick E.
metallurgist/trouble shooter....
Our plant makes thin stamped parts, our customer has alerted us to a problem with residue on the surface of the parts. This residue seems to be compressor oil. Our shop air system is fed with Atlas Copco compressors I think they are screw type. (standard shop air ~100to 120psi)
There is a robot that uses air blowoffs as part of its handling. What are the different levels of fitering I can reccommend to my boss as ways to prevent air from reaching the robot?
(Currently I have some minor experience in asssuring I have clean dry air for the lab. I have had sucess with wilkerson using a 5micron dryer/filter followed by a .5micron oil coalescing filter.)
Nick E.
metallurgist/trouble shooter....





RE: Shop Air Supply Cleaning
First of all, if you value the quality of the stamped parts you are producing and selling, then I would strongly advise you to use an adsorption system downstream of the screw compressor discharge. I'm presuming the screw compressor you're using is OIL-FLOODED and, if so, this should have alerted everyone to what would happen if the air were applied on the parts. If you want quality parts you must employ quality air.
I would have assumed you were using dry air as a "blowoff" and, as such, also an adsorption dryer. This would automatically remove the water and the oil in the compressed air coming from the compressor. However, if that's not the case, you can install an oil sorber - a fixed bed of either activated alumina or another adsorbent such as activated carbon. I favor the use of activated alumina in these cases because I suspect your operation is not continuous, around the clock and the quantity of air used is relatively low in total quantity. Using activated alumina, you can visually "see" the trapped and adsorbed oil on the adsorbent and this allows you to monitor the depletion of the adsorbent and change it out before the oil "breaks through" - a term meaning that the oil in the air passes through the entire bed due primarily to the bed's loss of sorptive ability. You can also use activated carbon, but it's impossible to detect the oil's progress in the carbon.
You would normally use a batch vessel (or cannister, if your amount of air is really low) and manually change the adsorbent before it depletes. The time it takes to deplete is dependent on your usage of air. Find the root cause is not difficult. Many times you can prove the oil contamination by blowing the air into a pad made of tissue paper. The oil stains are obvious when the contamination is heavy.
Hope this experience helps. I've solved this problem many times by using adsorbers with either activated carbon or activated alumina. I know I can produce food-grade quality air with this operation.
RE: Shop Air Supply Cleaning
Once you get the screw working perfectly, then the media in the filter that Montemayor recommends will last longer and work better.
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
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RE: Shop Air Supply Cleaning
RE: Shop Air Supply Cleaning
RE: Shop Air Supply Cleaning
Atlas-Copco makes both flooded and dry screw compressors. If you have the later the problem is inlet air or a seal failure on the inlet to the first stage.
RE: Shop Air Supply Cleaning
But remember the old adage. Clean dry instrument air is an oxymoron.
rmw