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Russ, Here are a couple of old post that are close at hand : Maybe not exactly what you had in mind but at least closely related. ============================================================= From: <pdisler@io*.ne*> Date: Fri, 16 May 1997 10:30:34 -0600 Subject: Re: O2 Cleaning BS ?? Art wrote: >I've read in a few posts that O2 cleaning is BS. Can someone >elaborate. From training I understood the reason was to remove >hydrocarbons. From what I understand, these are oil based and can >basically catch fire or at least prolong a flash. I'm not a certified >gas mixer, nor do I garage mix so I don't have an in-depth knowledge >of the subject. ART, I will tell you of an experience I had on 1 occassion approx 2 years ago. I was Changing out a needle valve on my O2/He manifolded PP mixing station. The one I had purchased was supposedly O2 compatible and O2 cleaned. There was a 2.5' section of braided teflon hose between the ball valve on the K bottle and the new valve I was installing. This was definitly a mistake. The valve should have been installed RIGHT after the ball valve and I should have O2 cleaned the needle valve personaly...WHY ? Because when I had completed the installation I began to test the system. The first thing was to make sure the needle valve was closed. The second was to turn on the ball valve as slowly as possible. I barely cracked the ball valve and found rather quickly that there was only 2 positions on this particular FAULTY K BOTTLE VALVE.....OFF AND WIDE OPEN (Most have at least some degree of control) When the short section of steel braided teflon hose was pressurized and it struck the new valve there was an immediate combustion inside the hose...yes a fire inside the hose that originated right next to the new valve glowing bright red and was rapidly moving toward the K-bottle of O2. All I had time to do...all I could do... was to shut the valve and run like hell. Seconds later the hose burst and the pressure dropped a split second later. This is all that it took for me to realize that once something is ignited in pure O2...anything will burn. It also occured to me that had I not shut off the O2 K-bottle valve when I did after the hose bursted it would have continued to burn the hose as it whipped around and most likely would have been a real problem to get close enough to extingish. After this little episode... I pulled off the new needle valve, disassembled it and found a deep scorched pit in the side of the needle where some sort of tiny particle struck and caused the ignition. I also found some trace hydocarbons within the same valve body. Now I make damn sure not to repeat this mistake and I do O2 clean every component of my PP blending systems. From what I was told O2 is different than other >gasses in that it gets HOT when going from a high pressure to low. > Someone once told me that in a standard SCUBA tank, O2 rushing from >3000psi to ambient through the small opening of a tank valve can flash >to 1500 degrees F almost instantaneously if the valve were opened all >the way immediately. Don't know if this is correct or possible so if >someone knows this is BS please tell me. I was "told" this so again >I'm not sure. I did see some valves which were supposedly "melted" in >this way. > All it takes is one little spark from a piece of lint or a lot of friction from O2 flowing to rapidly and the hose is an inferno...trust me on that I have witnessed this to be true. Friction creates heat (kinda like rubbing two sticks together to make fire. Only in a pure O2 environment most anything that will burn... will burn just that much faster. Like rubber hoses, like teflon hoses, like the trace hydrocarbons found in most scuba compressors that find there way into a scuba tanks,regs,hoses,etc..... >With this in mind, the use of O2 safe o-rings and grease will not >promote or prolong a burn. I think O2 safe is basically that it will >disintegrate instead of burning. Even with O2 compatible components....the risk is only reduced. Cleaning, compatibility.... combinded with proper filling techniques should be followed to the best of ones ability....In my opinion...Sure will not hurt. I don't see any reason why this same type ignition could not occur in say a pressure gauge hose that was once used for regular air at one time or one that had not been O2 cleaned and had some trace hydrocarbons. In the low pressure side of a reg and hoses...I don't know. But I suppose its a real possibility there too. Hope I never find out the hard way. > >Unless I forgot, was grossly misinformed or really confused, this is >what I was taught in my Adv. NITROX class. Am I wrong? Why are >people saying O2 cleaning is BS? Can't speak for most people.....but I believe there is a definate and correct way to do pp fills...and O2 compatable-clean components is the first step. > "SILT HAPPENS"JD JEFF DISLER SAFE DIVING NSS 26000 ======================================================= Date: Tue, 20 Aug 1996 19:42:18 -0400 (EDT) From: "Eric Zimmerman (BIO)" <ezimmerm@ch*.ca*.us*.ed*> Subject: o2 cleaning and jackson blue just a side note that i have 1st hand experience with-a nitroxtank was returned to a friends shop after being rented and used in the keys,it was dumped and partially filled with o2, as it sat on the whip it made cracking noises and became so hot it could not be touched on the valve. The heat was enough to melt the hp seat in the valve, must have been an oily compressor in the keys. ======================================================= Chuck -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send list subscription requests to `techdiver-request@aquanaut.com'.
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