Overall, acetylene is safer, as it is lighter than ambient air and
does not out gas and pool to the floor, as does propane. However,
with propane, it depends on the size of the tank you use. If you use
the very tiny propane tanks, about 1 foot in length, these are quite
safe and don’t vent. The larger B size will, as will the BBQ style.
Acetylene in the B size (about 2.5 feet) is fine.
When to change your tank? Acetelyne is mixed with acetone. At 25psi,
I usually make the change at that point.
When switching out tanks, always, always, always, (did I say
always?), make a leak test. When I get my tanks refilled, I check
them right then and there with my hoses and regulators at the welding
supply where I get my gas. I have found, one more than one occasion,
where leaks were present on the square fitting where the tank key
turns on the gas. Welding suppliers, clink and clank tanks all day.
They don’t care the way we care, (well maybe they do). However, when
I am driving home with gas in the back seat in its little seat belt
with the window cracked open, I want to know that the tank is working
properly before I become a scene in an action blow up thriller.
Yes, it is fine to drive with your tanks in your car. You drive with
a gas tank in your car. However, up end your tank and let it settle
for at least an hour. This gives the acetone a chance to rest back
into the bottom.
I use a double regulator, meaning one that measures the gas pressure
in the tank and one to measure the gas pressure in the line to my
torch. Now that little T bar on the regulator? When you turn off your
gas and bleed the line, unscrew the T bar on the regulator, meaning
turn it counter clockwise, like you are turning down the volume on
your tuner. I find more people, cranking the regulator tight thinking
this is the “off” position. No, this is the “on” position.
A regulator contains an interior rubber diaphram which detects how
much pressure is being REGULATED through your settings. If you leave
your regulator in the “on” or cranked in position, eventually you
will wear out the diaphram and you will lose the sensitivity on your
For those using oxy/fuel for the first time and trying to figure out
the order to turn on the fuel and the propellant (oxy), just remember
This stands for:
Gas on (light it up)
Oxy on (regulate flame)
To turn off:
Oxy off (to cut off the propellant)
Gas off (to cut off the fuel)
Strikers for Gas/Oxy. I don’t use them. I find that the gas pools
too much in the striker compartment and WOOSH when the spark hits. I
really like the little automatic battery operated clicky things that
give off a continuous spark. There is a nice round one with four
access points. Nice design. A little gas and it ignites away. Great
for people who are lefties, as the strikers are designed for
For Smith Air/acet users. About once a month, check the integrity of
the two “O” rings and make sure there are no cracks. This torch tip
depends on a very tight fit between the torch tip and handle. The
handle will get hot, if the o rings are not working properly.
Bleeding lines. After the gas is turned off, I light my torch and
when the flame is gone, so is the gas. Turn your torch off and back
off the regulator.
Lastly, something that people don’t address enough. Flashback
arrestors. Get’em, use em. Especially if you are going to solder at
home, or anywhere.
Hoses, check for leaks here too. I had leaking aceteylene in my
basement, and couldn’t for the life of me figure out where it was
coming from. I did leak tests, regulator checks, fitting checks,
nothing was making sense. Then I did a close inspection of my rubber
hose. Ah. Seems that my cat Heloise found that the rubber was a
perfect toy to munch on, and I found tiny cat tooth punctures in my
If your hose on your straight Prestolite or Smith air/acet has been
around for more than five years, replace your hoses. The rubber can
break down and become brittle. If you don’t believe me, ask the
famous sculptor Albert Paley who nearly burned to death using
propane/oxy on one of his large sculptures, and an old hose cracked
and ignited the gas for 20 feet, right up to his face. He’s ok, but
old hoses should be checked.
I know this is a long discourse on a simple question, but I suspect
there are newbies lurking and this is for you folks.