From: kimberln@crl.com (J. Kimberlin)
Newsgroups: rec.crafts.metalworking
Subject: Re: Acetalene vs Propane brazing
Date: 19 Mar 1996 17:15:28 -0800

In article <DoIqMA.4vw@uicc.com>, Bob Neidorff <neidorff@uicc.com> wrote:
>Peter Brooks (brooksp@hpcc01.corp.hp.com) wrote:
>: I think an acetylene regulator is all wrong for propane; if only because
>: propane is run at a lower pressure in its tank.
>
>This is NOT a likely case, but I feel it necessary to say.
>
>VERY IMPORTANT: Do not run a propane regulator on acetylene.
>Acetylene regulators contain special gaskets that are immune
>to the solvent fumes found in acetylene.  Propane is purer,
>so propane regulators do not need these special gaskets.
>Acetylene can ruin a propane-only regulator, cause leaks,
>and otherwise cause danger to the user.


Bob, this is an important issue.  It is true that one can use an 
acetylene regulator on propane, but it is equally true that the acetone 
in the acetylene regulator may eventually swell any butyl or other rubber 
o-rings or gaskets in a propane regulator.  If one can find a regulator 
using teflon or other fluorocarbon gaskets and diaphram components, one 
might be able to simply interchange the regulator from acetylene to propane.

People tend to use the acetylene tank until it is empty.  The basic rule 
is not to let an acetylene tank go lower than 75 psig before refilling.  
Once the tank goes below 50 psig, acetone vapors emerge and get into the 
regulator.  If we could be sure that no one let the tank get below 75 
psig before refilling, then the propane regulator *might* be used.  This 
is not the usual case for people exhibiting the normal economic.  Thus 
your warning is certainly worthwhile.

In any case a real shop person would not want to use a recreational 
vehicle type propane regulator in the shop.  I use one of these on my 
locomotive but not in the shop where one needs a full fledged single or 
double stage regulator with 2 gauges.

JerryK