As you recently intoned, RIX has compressors (and amplifiers) for pumping O2. The SA6 is not recommended for this, or for pumping any type of dry gas. Doing so will cause the compressor to overheat. The overheating problem you describe for this type compressor is caused by a lack of humidity at the inlet (the SweetAir6 is water lubricated). One solution is to inject water vapor into the stream. A fogger and 'T' coupling should do it. The trick is to avoid injecting too much air which can dilute the O2 or Nitrox. The vapor should be injected upstream, into the blender if possible, or downstream from the inline demand regulator for O2. The conversion will turn the RIX SA6 compressor into something more than an expensive engineering curiosity. It'll still be expensive but-- oh, I forgot, you don't wish to discuss cost.
'Expert'? If you check, you will see I describe myself as a 'tinkerer', that's all.
The subject of this thread is filtration of the output of surplus, used compressors. I've jumped in because I know there are a lot of divers who cannot afford a 'Cadillac' because they've previously asked for guidance on an inexpensive compressor. I would like to see compressors in the hands of more divers to encourage independence and adventure. If I can encourage this by allaying some fears then my job is done. The engineering advice is, as always, gratis.
Edit: I forgot to mention; A final filter is desirable for any compressor to suppress excess humidity. However, when pumping oxygen, the filter cartridge must contain no carbon and the last filter pad in line before exit of the gas should be a clean 40 micron or better. The Navy requires 5 micron and if these are available to you that's what should be used. Of course, never pump anything richer than 36% Nitrox with an oiled compressor.
Pesky
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