makezine.com/52
Getting Started with Propane and Fire Effects
Materials
» Propane cylinder, standard 20lb
(5gal)
» Propane regulator, low pressure
such as a gas BBQ regulator
» Ball valve, gas rated, 38" FIP ×
38" FIP
» Propane hose, high pressure, ¼"
MIP × 38" FFL
» Brass bushing, 38" MIP × 38" FIP
» Brass bushing, 38" MIP × ¼" FIP
» Teflon tape, yellow (gas-rated)
» 38" flare plug fitting (optional)
to fit hose end, for leak testing
Tools
» Adjustable wrenches (2)
» Safety glasses
» Spray bottle
» Dish soap
» Towel
LEAK TESTING
1. Put your safety glasses on. Verify that the ball
valve is turned off.
2. Attach the regulator’s QCC fitting to the propane
cylinder without Teflon tape. If your regulator has a
large plastic grip around the fitting, it is threaded by
hand. If there’s no hand grip, tighten with a wrench,
but do not overtighten; some regulators won’t
supply propane at all if overtightened.
3. Open the cylinder valve all the way and then back
off about a half turn.
4. Using a little soapy water in your spray bottle,
spray the fittings from the cylinder to the ball valve
(Figure
C
). Check for bubbles. If you see any,
depressurize and tighten the joint until they stop. A
valuable addition is a 3/8" flare plug to cap the end of
the hose; this will allow you to test the ball valve-to-
hose connections as well.
5. Close the cylinder valve all the way and then
open the ball valve to vent the line.
That’s all there is to constructing a low-pressure
source for all kinds of fun flame projects.
51makershed.com makezine.com 51
TAPING AND TIGHTENING
THREADED FITTINGS
TAPING JOINTS
I’m a taper, not a doper. Therefore, most of
the joints in my book, other than the flare
fittings, rely on yellow Teflon tape to become
gas-tight. Taping a joint correctly is easy to
do. Four wraps of tape clockwise around the
fittings will do the job. Use your thumb to hold down
the first wrap so it doesn’t slip. Wrap with enough
tension to allow the threads to make a sharp
crease (but don’t overdo it), and don’t let any tape
hang over the inner passageway of the fitting.
When the wrapping is completed, pull the tape
until it breaks itself off at the back of the threads.
If you take apart a taped joint, use a wire brush
to get all of the old tape out of the threads (on both
the male and female sides of the joint). Never
retape over old tape. Tape is relatively cheap. Pull
a joint apart and retape if you need to; it’s better to use a
little extra tape than to have an unsafe joint.
TIGHTENING
How tight should you tighten threaded fittings? Unfortunately,
the answer is, Tight enough to stop the gas from leaking.”
This isn’t typically described in terms of torque — its
something you develop a feel for. I typically tighten a taped
NPT fitting until it starts to feel like it won’t turn much more,
and then I give it a turn or two more. Thats vague, because the
difficulty varies tremendously between fittings (and people’s
ideas of difficult). So tighten it and then leak-test under
pressure to get a feel for it.
The important tip here is to always use a wrench to brace a
part you don’t want to have move. Use the second wrench to
tighten the next part into it.
WHITE TEFLON TAPE. It’s too thin, so it
shreds and clogs your valves and fittings.
Use yellow gas-rated Teflon tape.
CAST IRON BUSHINGS. They’re too brittle;
they’ll crack under torque, then leak gas.
Use brass bushings.
HOSE CLAMPS. Theyre not rated for gas
pressures. Use pre-fitted propane rated
hose instead.
PLASTIC VALVES.
Typically designed for
water or other liquids at pressures far
below gas ratings. Plastics may also be
corroded by propane. Use brass valves.
COMPRESSED AIR FITTINGS. They’re
unrated for gas pressures, and they
frequently have rubber seals that will
corrode under contact with propane. Use
gas-rated fittings with appropriate seals.
Low-pressure source block diagram.
C
CAUTION
DONT USE
Leak-test the low-pressure source.
Tim Deagan, James Burke
Tim Deagan
M52_048-55_SB_F1.indd 51 6/13/16 1:09 PM

Get Make: Volume 52 now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.