If acetone got into an acetylene regulator, could it cause
sputtering? How about leaks? My regulator has the gauge needle going
up and down when I try to run it. I did a leak check and gas was
leaking at the connection between the tank and the regulator. Could
it be bad tank threads? An undertightened regulator? This is for a
little MC tank. I find it really hard to try to tighten the nut
without the bottle turning.
Thanks for your help,
You didn't get any other replies, probably because most folks would be
afraid to give advice on this one. This situation is potentially so
dangerous that they probably don't want to get involved. I know I
wouldn't unless I say this: Either throw the regulator away immediately
or take it and the tank to your welding supplier for advice.
I assume that you must have been using the tank on its side to need
to ask this question.
How do you figure that? An MC tank is barely larger than a propane torch tank
only holds 10cf in the standard fill. Hard to imagine much of anything so
that one would be afraid to give advice. (Lack of a round tuit is the reason
delay) Hard to imagine much danger, period.
I used to own a compressed gas distributorship. Does that count?
Bad assumption. Especially on MC and E tanks, too rapid a withdrawal will cause
acetone carryover. In any event, I've never had any problems operating an MC
its side and firing either a Prest-o-lite or a mini oxyacetyelene torch, both low
demand applications. Too little acetone too tightly bound to matter much.
You didn't say how much the pressure is varying. Aged regulator needle valve
(neoprene or equiv) will get soft. This results in the needle sticking,
the force needed to unseat the needle. The result can be pressure pulsations
of smooth linear regulation. The seat has to be resistant to acetone because the
acetylene is saturated in acetone vapor when it exits the tank.
I've seen otherwise OK regulators that would pulse when the tank was almost
that's the case here then your regulator might be OK.
NO, bad threads are not involved. No CGA gas fitting relies on the threads for
sealing. The seal is a metal-to-metal joint and the threaded nut simply
force necessary to hold the two mating parts together. Only a snug fit is
you're having trouble holding the tank then you're tightening WAY too tight.
The tank fitting has a concave spherical mating surface and the spud (the part
screwed into the regulator, also called the nipple) has a mating convex surface.
must be clean, smooth and symmetrical to achieve a seal. Inspect both for burrs,
dirt, digs and warpage. If you tighten the nut finger-tight and then spin the
regulator back and forth a little, you should see a continuous shiny band of
brass on both the tank and spud. If you don't see these shiny rings then one or
mating surfaces probably have been damaged, either from dropping or
Given how cheap MC regulators are, I'd not spend much time on this. Do just
to verify that the tank valve's mating surface is OK, then toss the regulator
John De Armond
See my website for my current email address
Answering "how do you figure that?" A friend of mine brought a failed
acetylene regulator to a meeting a couple of years ago. He told about
how quickly the regulator caught on fire and how hard it was to get to
the valve that was in the middle of the fire. Acetylene is one of
the most dangerous flammable gases I know about. And you certainly
don't want a regulator to tell you that you've got 15 psi when it's
I wasn't running the tank on its side, I was transporting it on its
side and only waited for about an hour before attempting to use it.
This is a little peanut rig that I bought new and hadn't used for
several years. It worked fine the last time I used it. I guess I'll
take it in.