The best way to protect your studio from a fuel gas flashback, and
this applies to any gas, not just natural gas, is to use a UL
Approved Combination Check Valve and Flashback Arrestor. All major
distributors have a product of this type in their catalogs and they
cost less than $100 for a pair. One flashback arrestor goes on the
torch hose and the other goes on the oxygen hose.
If your torch has threads at the handle base then you want "torch
mount" flashback arrestors which will screw right onto the torch
handle. Many torches have "B" size threads but if your torch, for
example a Midget, has "A" threads (similar appearance but smaller
size) you can get "A" to "B" adapters at your welding/fuel gas supply
store. Torches used for casting would use torch mount flashback
If your torch has barbed fittings, where you slide the hose on then
use a clamp ring, then you want "regulator mount" flashback
arrestors. These flashback arrestors are connected at the regulator
for the oxygen tank, and either on the black pipe for natural gas or
the regulator for propane. Hoke and Smith "Little" torches would use
regulator mount flashback arrestors.
The difference between these two types of flashback arrestors is
which direction gas is supposed to flow, and which direction of gas
flow is stopped by the arrestor. If you use the wrong one it will
block gas from reaching your torch!
Jewelers do not blow themselves up everyday and many people have an
attitude that "It won't happen to me", but that fact is there are
accidents. You can read more about the dangers of flashbacks at
jewelry manufacturers in New York City here:
To digress a little...
Scott Geller, of Safety Performance Solutions, has studied behavior
attitudes toward safety and puts people into two groups. One group
looks at safety in terms of problem avoidance - they act to avoid a
problem. If you think you are unlikely to be touched by the problem
or the price of solving the problem is more than the cost of the
problem, you are willing to live with a situation that others would
say is unsafe. If you think you will not experience a flashback or
the cost to install a flashback arrestor is more than the
consequences then you are unlikely to install one.
Another group of people looks at safety as a means to success and
associates it with positive outcomes. Working safely is just part of
an overall equation that includes good tools, good design and good
materials to produce a quality product. A safe workplace contributes
to working conditions that produce superior jewelry.
You can find a longer article about this topic in the July issue of
MJSA Journal on page 36.
National Fire Code regulations require a flashback arrestor on any
torch using fuel gas (whether acetylene, propane, natural gas, or
anything else) and oxygen, but whether you put a flashback arrestor
on your torch will depend a lot on your attitude toward safety.
G-TEC Natural Gas Systems