From: John De Armond
Newsgroups: rec.pyrotechnics
Subject: Re: Grease in O2 regulators...(Was Re: Old cutting torches)
Message-ID: <dj1v1pp@dixie.com>
Date: 3 May 93 02:31:31 GMT

moroney@world.std.com (Michael Moroney) writes:

>khartman@fnalo.fnal.gov (Ken Hartman) writes:

>>	While we're on the subject of Acetylene and torches, can someone
>>explain the rule:  Never grease or oil an Oxygen regulator.  I understand
>>the reason (an oxidizer combined with a fuel), but I don't see how simple
>>contact could start a fire without some form of heat to initiate the reaction.

>Check a freshman chemistry book of equilibrium constants and how rates of
>reactions depend on the concentration of ingredients.  Then consider that
>an oxygen cylinder is 2000-3000 psi pressure of pure oxygen, while air at
>normal pressure is a little over 3 psi partial pressure of oxygen.  Or up to
>1000 times the concentration of oxygen.

That is not the issue.  Oil in the presence of high pressure oxygen at
ambient temperature will not ignite without outside influence.  The issue
is the heat generated from the sudden compression of whatever low pressure
oxygen exists in the regulator when the high pressure valve is opened.
Adiabadicly compressing room temperature oxygen to 2200 psi generates
well over 1000 degrees F of heat.  The combination of high pressure, high
temperature and high oxygen content.

While on the subject, even where the regulator is absolutely clean, slamming
the high pressure valve open can cause a regulator explosion.  The needle
valve in the regulator is almost always tipped with a polymer, typically
Teflon.  The heat of compression can ignite this tip.  With the valve
burned away, full tank pressure is applied to the regulator diaphram and
body which promply explodes.  I saw many regulators blown up in just
this manner when I had the store.

John