My new Victor torch set came with the backflow preventers already
mounted on the torch.
A Google search located an Oregon government safety site that said the
backflow preventers must be installed at the torch.
This Oregon government site says the same thing, on page 12.
The California site below says they can be located in either place, but
the document is refering to a system in which acetylene is piped around
the shop, not where bottles are used, which I assume is your case.
Based on my review, I believe that mounting the backflow preventers at
the torch is standard industry practice, unless someone can produce an
official document that says otherwise. Obviously you could buy an extra
set and install them at both ends, but that is probably overkill, given
that backflow preventers were not even standard practice until
My philosophy is to follow standard industry practice, I generally
figure that standard industry practice is reasonably safe. Personal
opinions are all over the map, you can find someone to support any
position, including that the earth is flat. Industry practice is
usually more of a consensus of experts, a safer bet.
Tod Eng> Where do I put the backflow preventer on my torch set? At the regulator end
They should be at the torch end. Backflow preventers are not fire
suppression arresters. They prevent the higher pressure oxygen gas from
flowing into the acetylene hose should the torch tip become fouled or
blocked. Mostly when your torch is set up for cutting. If the oxygen
gets into the acetylene hose or regulator then fire is the least of
your worries. BOOM BOOM time.
Same reason you should also de-pressurize your hoses when your done for
the day. Acetylene can migrate from the acetylene hose into the oxygen
hose over a long period of time.
Play safe and be happy
Torch end. Putting them at the tank end does no good. Their purpose is to prevent
mixing of gases in the hoses, so combustion can't occur in the hoses. The very
high pressures in the tanks prevent backflow through the regulators, so backflow
preventers don't do anything for you if placed at the tank end of the hoses.
It isn't. The only place mixed gases can be forced into a hose
is at the torch end of the hose. If the tip becomes blocked, the
higher pressure oxygen can flow through the torch mixing chamber
and back into the lower pressure acetylene hose, forming a
combustible mixture there. The check valves *at the torch*
prevent this. Check valves at the regulators don't do anything