Is it safe to continuous blend nitrox using an older compressor? I have read that you need to change to synthetic oil but I have also read that changing to synthetic in an old compressor can lead to problems. Can I just blend usin it as is if I am mixing well under 40%?
Continuous Blending with an old compressor.
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I think the general consenus is that you should use synthetic oil because of it's higher flash point for pumping nitrox.
It is true that during the change over you may experience problems because the synthetic oil may dislodge carbon deposits etc inside the compressor. This may cause some problem with the high pressure piston/valves.
Usually it is suggested that the oil be changed several times during the change over. Running the compressor for short periods and changing the oil on the initial phase while using the sythetic oil. Basically put the synthetic in and run the compressor for only a few hours and then change the oil again. Then run it for a few more hours and change the oil a second time. After the second oil change you can run the compressor longer (perhaps 10 hours) before changing the oil again. After that the usual 25-50 hour interval between oil changes should be ok.
There is of course always the chance the deposits could damage the compressor even with the change over method noted above.
Skippy31
It is true that during the change over you may experience problems because the synthetic oil may dislodge carbon deposits etc inside the compressor. This may cause some problem with the high pressure piston/valves.
Usually it is suggested that the oil be changed several times during the change over. Running the compressor for short periods and changing the oil on the initial phase while using the sythetic oil. Basically put the synthetic in and run the compressor for only a few hours and then change the oil again. Then run it for a few more hours and change the oil a second time. After the second oil change you can run the compressor longer (perhaps 10 hours) before changing the oil again. After that the usual 25-50 hour interval between oil changes should be ok.
There is of course always the chance the deposits could damage the compressor even with the change over method noted above.
Skippy31
This is an old Bauer Capitano that came out of a fire dept. It has allot of hours on it but it works just fine. I'm sure over the years there are built up carbon deposits. If it was safe to mix Nitrox as is I would try it but for my limited need I'm not sure I want to chance messing up a good compressor by changing over to synthetic. What do you think the odss are? Is it 100:1 or something like 5:1?
fweber
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What are the ODDS? Are you really going to let a bunch of people guessing over the internet, decide this for you? And even then, what "ODDS" would you find acceptable? And if you happen to be that "1"?
Originally, Nitrox was only blended in Oilfree compressors. Since then, people have begun using Synthetic lubicrated compressors. Some have even successfully converted older compressors to running Syn.
But, to take an admittedly old, high hour, mineral oil lubed compressor and start continuously mixing through it, just isn't something I would expect anyone I respect to endorse. And if they did, I don't know that I could continue to respect their opinions.
Originally, Nitrox was only blended in Oilfree compressors. Since then, people have begun using Synthetic lubicrated compressors. Some have even successfully converted older compressors to running Syn.
But, to take an admittedly old, high hour, mineral oil lubed compressor and start continuously mixing through it, just isn't something I would expect anyone I respect to endorse. And if they did, I don't know that I could continue to respect their opinions.
pescador775
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Catchaser, don't worry so much. Fire departments usually practice regular maintenance. Unscrew the top of the intermediate condenser and inspect. If your compressor has been running on mineral oil you will find deposits of wax. Clean the wax out of the blow off valve (use a probe or solvent) and the brass strainer. Pay attention to reassemble correctly. There may also be some deposits in the third stage valves. Don't worry about this unless the valves are clicking loudly. Bauer warns about changing over to synthetic but this is mostly theory. The main concern is possible clogging up of the cooling lines as the new synthetic oil, which has a polarized molecule and acts as a solvent, dissolves some of the gunk. Don't worry about carbon specifically. There can be deposits on the pistons and valves but the amount is likely to very little, 10 or 15 grams. The sump will contain some black stuff. Drain the old oil and insert a liter of Chemlube 800 (40W) or Chemlube 501(30W). Run the compressor for a while and drain, refill. That's it, you are good to pump Nitrox 36. First time you pump the gas, watch the oxygen level. An old compressor will have more blowby at high pressure requiring the oxygen to be dialed down a little as the fill progresses. If you want to be adventurous, get the 30W "food grade" oil from NUVAIR. That is what I use in my Capitano.
pescador775
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About the food grade oil, this is a synthetic mineral oil which contains no wax. However, it does contain high pressure anti-friction additives among other things. The type that I recommend is NUVAIR 455. This oil is identical to Ultrachem's high tech stuff, Omnilube 455; it does not have strong solvent properties but since it is very resistant to oxidation is not likely to produce significant deposits of any kind, nor will it stir up existing deposits to a significant degree.
What I did was run synthetic diester (Bauer oil) to flush some of the gunk left over from the original petroleum oil, then changed over to synthetic mineral oil, food grade. I can't say how much, if any, residue was removed by this procedure but have seen no problems either way.
What I did was run synthetic diester (Bauer oil) to flush some of the gunk left over from the original petroleum oil, then changed over to synthetic mineral oil, food grade. I can't say how much, if any, residue was removed by this procedure but have seen no problems either way.
pescador775, thanks for the information. Your right, I need to just do it and stop over analyzing it. I tend to be a worry wart about this kind of stuff. 
The valves don't click so I will probably be fine. I'll clean out the blow off and switch it over. I do like the idea of the synthetic mineral oil, that might be a closer oil to what these compressors were originally designed to use.
The valves don't click so I will probably be fine. I'll clean out the blow off and switch it over. I do like the idea of the synthetic mineral oil, that might be a closer oil to what these compressors were originally designed to use.The Curly One
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I think it is always a good idea to run a good synthetic oil such as Chemlube 751 or 800. I agree with Pescador, do not worry or over analyze it just put the good oil in there and run it.
The Chemlube 751 and 800 is a full synthetic with a much higher flashpoint than a mineral base oil with better lubrication to. I think the Chemlube 751 and 800 are the only oils that Bauer or ALKIN use and approve of. That should tell you something.
Do NOT ever put that "Food Grade" stuff in an ALKIN compressors. Using the wrong oil will definatly cause problems and gum up your valves.
The 751 is the same weight as the 800 (40wt)but the 800 has a different additive packege and has about 5* higher flashpoint. But it costs about $10 more per gallon. 751 is good for most all applications for breathing air.
The Chemlube 751 and 800 is a full synthetic with a much higher flashpoint than a mineral base oil with better lubrication to. I think the Chemlube 751 and 800 are the only oils that Bauer or ALKIN use and approve of. That should tell you something.
Do NOT ever put that "Food Grade" stuff in an ALKIN compressors. Using the wrong oil will definatly cause problems and gum up your valves.
The 751 is the same weight as the 800 (40wt)but the 800 has a different additive packege and has about 5* higher flashpoint. But it costs about $10 more per gallon. 751 is good for most all applications for breathing air.
pescador775
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Not to put too fine a point on it but here is the scoop. Bauer got stung by reports of poisonous gas being generated by diester oils like 751 in their compressors. Broadly speaking, this is a rare occurence; the two incidents which I have proof of were in Florida and Georgia, the second became public because of a lawsuit, the first due to an investigation and air testing following a serious incident and was widely reported. In response, Ultrachem and Anderol came up with some tougher, less volatile oils. The Anderol oil may be hard to locate but Ultrachem is producing a thick, high flash triester oil called "800". That is what Bauer recommends (we are talking Bauer here, right). Bauer confirmed that the 800 gives better performance in their machines when run under heavy load 24/7. However, they are tight lipped about NITROX, a legal thing probably. This stuff can be found at paintball shops and the like. I guess Global is carrying it by now. I avoid the issue altogether by using a synthetic mineral oil. Chemlube 455 is not like the stuff sold by Global and UBS, it is far more advanced than other synthetic "fluids" sold under various names like EZ1000, etc. BTW, one of the largest NITROX pumpers in Florida uses only FG oil in their equipment. Either way, catman, leave the worrying to guys like me who actually enjoy researching this stuff. LOL.
PS: After draining synthetic diester for the first time, besides inspecting the insides of the intermediate condenser, also remove the oil line from the pump. This line incorporates a small inline filter or screen. Blow some air through this thing to verify it has good flow then screw it back into place. Five minute job.
PS: After draining synthetic diester for the first time, besides inspecting the insides of the intermediate condenser, also remove the oil line from the pump. This line incorporates a small inline filter or screen. Blow some air through this thing to verify it has good flow then screw it back into place. Five minute job.
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