bleed the line (unlit, using ventilation) until both dials read
“0”
screw out the T-stem
make sure the knob is closed on the torch, before hanging it up.
I once called Smith Torches to ask about the practice that some
people have, of burning the excess gas, and they said that it is a
dangerous practice, because the flame can back down the hose, and
start a fire/explosion in the regulator or tank.
So, I would like to either:
-call attention to the danger of the practice of burning off the
excess fuel Or
-Hear from an expert why the expert I spoke to years ago was
incorrect. I wonder whether it makes a difference if check valves are
in use, for instance.
interesting! ok now i’m getting a bit paranoid. i was taught
something different. i was told to turn off the tank in the same way
i turn it on: first cut off the supply of gas to the hose from the
tank until the regulator reads zero then turn off the supply to the
hose until that reads zero then (while flame is still burning) allow
the gas in the hose to burn out then turn off the head of the torch
once the flame is extinguished very curious as to the right
approach!
1. turn off the flame
2. turn off the tank
3. bleed the line (unlit, using ventilation) until both dials read "0"
4. screw out the T-stem
5. make sure the knob is closed on the torch, before hanging it up.
This is the correct way to shut down a torch. While a flashback
arrestor at the torch could act to prevent a hose fire or worse it is
still not good practice to deviate from the procedure you outlined.
Check valves are not flashback arrestors and should not be relied on
to act like one.
Check valves are a must in my mind to be on the safe side. In the 35
years of being a bench jeweler and instructing the craft, I have
never had an incident of back flash through the hoses to the
tank…hey I am still here aren’t I?
As long as you have your check valve in place you will be ok…but I
would shut the flame down, oxy then gas, shut off tanks, bleed the
lines and then take out the valve pressure screws. That way no flash
back and this will make your valves last longer.
bleed the line (unlit, using ventilation) until both dials read"0"
screw out the T-stem
make sure the knob is closed on the torch, before hanging it up.
I believe that any recommendations, no matter who makes them, must
be examined, so let’s take a look at the above.
1. turn off the flame.
I guess it is not a good idea to have flame going all night, so it
makes sense to me.
2. turn off the tank.
Another sensible advice.
3. bleed the line (unit, using ventilation) until both dials read
"0"
That one does not make sense. The gas is staying in your lines all
day long. Why could it not stay all night ? Lines are designed to
contain the gas.
From purely theoretical viewpoint, it is more dangerous to bleed the
lines, than leave it alone. However, if you are the one who sells
gases, then the recommendation makes sense, because your tanks are
going to be refilled more frequently.
4. screw out the T-stem.
Again, I have to ask why ? By constantly screwing the T-stem in and
out, you are screwing yourself. All you do is wearing out the
diaphragm seat, which would lead to leaks in a short order. The less
you manipulate the T-stem, the better for the T-stem it is. However,
if we use principle of “following the money” it is not hard to guess
where recommendation is came from.
5. make sure the knob is closed on the torch, before hanging it
up.
I can add to this by saying that before hanging it up, make sure that
the hook is there, and before verifying presence of the hook, make
sure that the light is on, so you can see the hook, and etc…
We know that knob is closed, because we turned the flame off in
recommendation 1.
Okay, from an old ironworker’s training that involves, primarily,
oxygen and acetylene:
first, turn off the fuel gas supply (tank valve); shut off the fuel
gas supply so that, should something happen, the supply lines have
only a non-flammable gas supply; then the oxygen tank valve; then
bleed the fuel gas out of the regulator; again rid the system of
flammable first; then bleed the oxygen regulator;
bleeding the system of both gases from the system is probably
academic but the idea is that non-atmospheric gases left in the
system can be corrosive;
then turn out the fuel gas regulator screw just until it releases
from the inside release mechanism; then turn out the oxygen regulator
screw, until you can feel that release; then shut off both torch
handle valves.
Again, some of this may be academic but it follows manufacturers and
safety guidelines.
As long as you have your check valve in place you will be ok...but
I would shut the flame down, oxy then gas, shut off tanks, bleed
the lines and then take out the valve pressure screws. That way no
flash back and this will make your valves last longer.
Again check valves are not flashback arrestors and should not give
you any sense of security in regards to flashback. Yes flashback
arrestors do have a check valve function but it is not what prevents
the flashback from passing through the arrestor. If all you have are
check valves in your rig get a flashback arrestor!
Again, I have to ask why ? By constantly screwing the T-stem in
and out, you are screwing yourself. All you do is wearing out the
diaphragm seat, which would lead to leaks in a short order. The
less you manipulate the T-stem, the better for the T-stem it is.
However, if we use principle of "following the money" it is not
hard to guess where recommendation is came from.
The safety aspect of this has nothing to do with the diaphragm life.
The issue is the abrupt flow of high pressure gas (Oxygen) past the
orifice in the flow regulation valve. An example of a typical design
is shown here
The poppet valve orifice has a very small area and high pressure
oxygen blasting in from the cylinder when the tank valve is opened
erodes the seat area of the valve and causes it to leak eventually.
In an extreme case if the tank valve is opened too rapidly the
friction of the gas passing the orifice of the valve seat can
actually cause it to burn, then you have real problems. Yes it takes
an ignorant or foolish person to open the valve that rapidly but it
has happened.
Regulators need to be serviced ocasionaly and have worn parts
replaced this is not about making money but safety in handling
hazardous materials.
I believe if you check with any valve company that sells these you
will see that the diaphragm is under pressure from a spring. Taking
the pressure off of the diaphragm from the spring will make is last
longer. So, screwing out the T-bar on the valve is a good thing.
Releasing the gases out of the line, as said before, from the torch,
releases the pressure of the gas in the line creating less
possibilities of leaks in the lines and fittings. I would rather pay
a little more for gas than replacing/repairing hoses or fittings. The
last point is that you may have turned off the flame in step 1 but by
bleeding the lines after the tanks are shut off from the torch you
have to close them again before hanging up the torch…eh don’t do
this and turn on tanks in the morning, with that cigarette lit and
you could be in for a wonderful cindering.
We know that knob is closed, because we turned the flame off in
recommendation 1.
Isn’t that a little overly sarcastic? We know that the knob was
closed as in recommendation 1, but it was then opened again as per
recommendation 3, to bleed the line, so recommendation 5 is good
advice in preparation for the next day’s start-up.
Unpopular these days. Also probably not OSHA approved, I’d guess. But
yes: Turn off oxygen valve, turn off acetylene valve and/or natural
gas stopcock. Turn off lights. Go home… For decades, now…
The poppet valve orifice has a very small area and high pressure
oxygen blasting in from the cylinder when the tank valve is opened
erodes the seat area of the valve and causes it to leak
eventually. In an extreme case if the tank valve is opened too
rapidly the friction of the gas passing the orifice of the valve
seat can actually cause it to burn, then you have real problems.
Yes it takes an ignorant or foolish person to open the valve that
rapidly but it has happened.
Let’s remember that I do not bleed lines. Given that condition, let’s
create a model.
Initial state:
Torch is shut off. Lines are pressurized. Tank is open. Regulator is
pressurized.
Let’s close tank. What changed?
If system has no leaks, absolutely nothing. Lines are still
pressurized. Regulator is pressurized as well. When we open tank next
morning, there is no rush of high pressure oxygen. Everything is the
same. That is why there is thousands of jewelers, who set their
regulators when they bought it, and never touched it again.
If you bleed the lines, than yes, when tank is open the scenario you
described is making sense somewhat. I would still question how much
damage is actually done to regulator, but the possibility does exist.
Solution is simple. Do not bleed the lines.
To address other concern about leaving lines pressurized weakens
connections and increases possibility of leaks.
My advice is to observe what happens to the lines during the day.
They are been twisted, compressed, stretched, stepped on - and with
all that abuse they do not leak. Why do you think that when you hang
your torch and go home and your lines are resting, they would develop
leak suddenly. I would have to say that the concern is misplaced. The
night is the most restful time for your lines.
This has me worried. I don’t know what everybody is referring to
when they say to screw out the T-stem. I’m obviously not doing this
step so I’m worried about leaks further down the line. I do
everything else on the list, in the order stated, but would
appreciate some advice about the T-stem. Thanks.
Unpopular these days. Also probably not OSHA approved, I'd guess.
But yes: Turn off oxygen valve, turn off acetylene valve and/or
natural gas stopcock. Turn off lights. Go home... For decades,
now...
NO NO NO John !!!
Bleed everything til your fingers hurt, disconnect the tanks and drag
them outside (1 at a time to be safe) and stash them in snow banks at
least 50 feet apart from each other. No snow… then 200 feet apart.
Consider moving to a more unpleasant climate in the interests of
safety.
If you have perfect hoses that will never leak and perfect valves
that will never leak and a perfect record of closing the valves
bubble tight then your scenario is just fine. But leaks show up when
ever not just during the day while you are in the studio. If you are
there you will probably smell the acetylene or propane or natural gas
before you have an explosive amount or at least you have a chance of
smelling it before serious trouble but if the hose gives up the ghost
at 5:15 just after you left the studio or you just did not quite get
that valve closed or maybe it is finally worn out and will not seal
bubble tight and leaks all night then the likelihood of an explosion
or fire is much greater.
So rather than relying on perfection it is safer to rely on the
steel tank and tank valve to keep the fuel gas from leaking out.
I don't know what everybody is referring to when they say to screw
out the T-stem.
it is the adjusting knob or T handle on your regulator. You just
want to back it off enough so that there is no longer any spring
pressure felt on it not really back it all the way out.
I would rather err on the side of no pressure in the lines. It only
stands to simple reason, if a leak occurs, which has happened,
whatever is in the line will get out. As the next day wears on, an
unsuspecting jeweler could be in for a nasty surprise…propane lies
on the floor and is not readily detectable unless you are down there
sniffing around. Constant pressure on the spring and diaphragm and
the lines is not a good scenario when not in use. I have owned a
trade shop for over 30 years and have done this several ways. The
best and longest lasting for the valves and the safety of all remains
in what I have stated before. Enough said on this subject, time to
move on.
This has me worried. I don't know what everybody is referring to
when they say to screw out the T-stem. I'm obviously not doing
this step so I'm worried about leaks further down the line. I do
everything else on the list, in the order stated, but would
appreciate some advice about the T-stem.
I truly appreciate the fact that everyone on this forum is concerned
with safety and is willing to assist with that, however, on this
topic it seems there are countless and extreme differences of
opinion and I for one am getting more confused than ever about how to
turn off my tanks and keep a safe environment. I am questioning
habits I never questioned before…but not sure what to replace
them with?? Can someone with a good amount of assurance (mindful
there are no guarantees as we are dealing with volatile gases) give
us the ultimate, safe instructions for turning off tanks at the end
of a session, for the various types of tanks one would use in
metalsmithing so all of us, especially novices can feel safe and not
live in constant fear of a terrible accident.
An old Navy Chief-machinist taught me a great trick- and one I use
today- Connect your car keys to the tank key. Now gremlins,
tank-mites, and “helpful” co-workers cannot turn on your tanks
without you being there- and when you are ready to leave, the tank
prompts you to get your keys to turn it off. I painted my tank-key
international orange just so I would have that visual.
-Flash arrestors and bleeding the torch after off are reccomended.
-Just my .02- Be safe and have a great day.