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Propane, Acetylene etc


#1

I found todays special edition digest about propane and
acetylene very informative. I am a professional engineer with 20
yrs of experience that includes design and operation of
facilities that process propane and other hydrocarbon gasses,
and I thought I would throw in my 2 cents worth by providing
some fact and some opinion…

MY OPINION - I would never consider bringing a 20 lb propane
storage tank or an acetylene B tank into my home. I believe that
it exposes me and my family to an unacceptable level of risk. A
leak of either one of these gases in a confined and
unventillated space such as a basement workshop can cause an
explosion large enough to seriously damage your house and injure
(kill) its occupants. I agree that it is possible to have these
gasses in your home for many years without an incident, but I
believe that the consequence of a leak and explosion is too high
for me to be willing to take the risk.

SOME FACTS TO HELP YOU MAKE YOUR OWN DECISION;

  1. Propane, acetylene, butane, natural gas will all explode
    violently if mixed with air in the correct proportions and
    exposed to a spark or flame and even a hot glowing piece of
    metal.

  2. Propane and butane are heavier than air and will sink or pool
    on the ground. Acetylene weighs about the same as air, and is
    referred to as neutrally bouyant, but still behaves a bit like
    propane and butane. Natural gas is lighter than air and will
    rise.

  3. Whether a gas pools or rises makes little difference in a
    confined space such as a basement studio or a back bedroom. One
    of these gases leaking in a room with little or no ventilation
    is just about guaranteed to form an explosive mixture with air.
    Once it finds an open flame it will explode.

  4. All propane tanks are equipped with a pressure relief valve.
    This is required by law to prevent a propane tank from over
    pressuring and ripping open. When a propane tank is overfilled
    (especially in cold weather) and brought inside into a heated
    home, or left in the sunshine by a window, the liquid propane in
    the tank expands and vapourizes and starts to pressure up the
    tank. The relief valve pops open and lets some of the propane
    out of the tank to lower the pressure inside the tank. This is
    just fine if the tank is located outside as the tank
    manufacturer intended, since the propane gas will disperse
    harmlessly, but not so OK inside your home.

  5. When transporting propane tanks in your car, ALWAYS transport
    them upright and leave your trunk slightly open. Transporting or
    storing a propane tank on its side could affect the ability of
    the relief valve to work, and if the hot sun warms up the
    propane in your trunk it can cause the propane tank to rip open.
    Also, it is a good idea to leave your trunk open a bit just in
    case the propane relieves out of an upright tank.

  6. If you feel that you really must bring these gasses into your
    home, you should consult the local fire department so that you
    know if it is legal and also to get some professional advice on
    how to safely handle the gas. You should also consult your
    insurer, to make sure that they will cover you in the event of
    an incedent.

And finally a bit more opinion. I do all of my soldering in the
garage, with the doors cracked open. I am a hobiest, and have so
far been content with smaller butane and propane torches. I am
planning to move up to a Prestolite acetylene torch. I will keep
my tank outside of my house in some sort of ventilated
enclosure, and always close the valves when I am done.

MILT FISCHBEIN P.Eng.


#2

Dear Mr. Fischbein,

Your message about acetylene and propane scared me! If we do
indeed have a studio in our basement or house we have no choice
but to keep our tank inside. My understanding was that acetylene
tanks have a lead plug that melts in the event of a fire-gas
escapes and there is no explosion.I have never heard about an
explosion with acetylene and have seen many "leaky regulators.
Would it help to keep the window cracked in the studio? Thanks
Jennifer Karotkin


#3

Your message about acetylene and propane scared me! If we do
indeed have a studio in our basement or house we have no choice
but to keep our tank inside…

Jennifer,

When I worked out of my basement, I kept the propane tank
outside, on two cement blocks, with a bucket over it to protect
the regulators. I put a quick disconnect on it and hard piped it
(1/4" flexible copper tubing) to my bench. Just had to drill a
small hole in the outside wall of the house. I connected my
torch hose to the end of the tubing. My shop now is large enough
that I can keep the tank indoors now (it’s the smallest B-B-Q
type tank they make and my store is 1200 sq. ft.). If you really
must keep it in your basement, and you are concerned about
confined space, you can build a leak proof dike around it to
create an area with a volume at least equal to that of your tank.
If you have propane, you will be able to smell it if there is a
leak. The stuff they add for odor is not heavier than air, and
will be obvious.

Hope this helps.

Sharon
GoldStones, Inc.


#4
 I have never heard about an explosion with acetylene and have
seen many "leaky regulators.Would it help to keep the window
cracked in the studio?  Thanks
           .............................

Jennifer,

As I mentioned, I would never keep an acetylene tank in my home
and I suspect it is against the fire code in many areas. I do
recognize that many people do keep B tanks in their homes and
have done so for years without incident. In the recent digest on
this topic there were quite a few opinions about the safety of
using these gases. I think it would be interesting if people who
have had experiences with leaking tanks or fires or explosions
would post details of the incidents for us all to read.

You asked about leaky regulators. A small leak from a regulator
is likely to harmlessly dissipate in a room with only moderate
ventilation (such as an open window). Once the gas has
dissipated, there is little risk of explosion. Any kind of
ventilation, including keeping the window cracked open would
help.

Most gas releases happen because someone makes a mistake and the
gas starts to flow out while they are standing near the tank. If
the tank has been set up properly, (see David Arens’ excellent
note in the July 28 Digest) it is usually just a quick quarter
turn of a valve to stop the gas flow and an incident can likely
be avoided. If proper procedures are followed and tank valves are
closed when the tank is left unattended, the tank is chained so
it can’t fall etc etc, there is only a small chance that gas will
leak from the tank.

Propane tanks are an exception to the above. Due to the nature
of the pressure relief valve on the tank, it is possible for the
valve to open at any time under certain condidions and release
enough propane into your home to cause a serious explosion.

You mentioned lead plugs in your note, so here is bit of
background on lead plugs and pressure relief valves:

When a flammable gas, or liquified gas (as in the case of
propane) is stored in a sealed container, the gas can expand in
the container if heat is applied to it. As the gas expands it has
no place to go, so instead of expanding it creates pressure in
the tank. The hotter the tank gets the higher the pressure gets.
The tanks are designed to handle a certain maximum pressure
safely. If the pressure inside that tank exceeds its safe design
pressure, there is a possibility that the tank will rupture.
Manufacturers of these tanks are required by law to protect the
tanks from exceeding their maximum safe design pressure. This is
generally done by installing a device on the tank that will allow
some (or all ) of the gas to escape from teh tank, thus relieving
the pressure and preventing the tank from rupturing.

A typical 20 pound propane tank, is generally equipped with a
spring type pressure relief valve. This valve will open at
perssures in excess of the design pressure and will close once
the tank pressure is below design pressure. The amount of propane
released will be limited to that required to reduce the tank back
to a safe pressure.

Most other gas tanks, and I believe that acetylene tanks will
fit into this category, have the lead plug that you refer to. It
is called a fusible plug. This fusible plug will melt if exposed
to very high heat which it takes to overpressure the gas tank.
Once it melts, it does not reseal like the valve on a propane
tank. This means that if it melts, all of the gas inside the tank
will be released, thus preventing the tank from rupturing.

The fusible plug will only melt when the tank is exposed to the
intense heat of a fire. It takes far more heat than just leaving
the tank in the hot sun, or lighting your torch near it. I have
never heard of a fusible plug melting unless there is a huge fire
around the tank.

You may be wondering why it is a good idea to purposefully
release the contents of a flammable gas tank into a fire as this
would continue to feed the fire and make it worse. The reason is
that if there were no relief valves or fusible plugs on gas
tanks, then if a tank overpressures and ruptured, it could send
metal fragments flying hundreds of feet with a very high and
dangerous force at the same time the gas is being released.

Hopefully this sheds some light on a confusing subject and has
not made it even more confusing.

As I mentioned at the beginning, I would not keep any of these
gasses in my home and you should consult your local fire
department for laws and safety regulations pertaining to the safe
handling and storage of flammable gasses.

Milt


#5

Perhaps the people that have had significant problems with these
gases never lived to reply here.

Mike McKim


#6

Re: exploding tanks

There was a message on the bead boards the other day from a
woman who was using a propane tank upstairs in her home. She
arrived home from work to find the upstairs filled with propane.
Apparently, it was very hot that day ,(of course, upstairs was
very hot, as it tends to be). This must have made the pressure
valve you were talking about release the gas- Oh, they did manage
to solve problem with out burning down house. What do you mean by
a dike around the tank?

anne


#7

I had an experience with a leaky acetylene tank. I had a faulty
regulater that busted a couple of days after recieving it and the
tank in the mail ( from Rio). It was my first torch and I wasn’t
sure how to stop the leakage, I was only a casual hoobiest at the
time…so I just left the house. The whole “B” tank leaked out
into the house. Several hours later I went back in and open all
the windows and turned on fans everywhere. The whole thing did
not result in any tragedy.

Rio was very apolegetic and replaced the equipment …and I
learned more about how to maintain a torch…I haven’t had any
other problems in the last 8 years.

Susan


#8

Since it’s been stated the even gas from a “b” tank will pool
at the lowest point, I don’t see where a leak would be HARMLESS.
And, I can’t imagine (if the pooling truly happens) that an open
window (usually at ceiling level) is going to help air out the
problem!

Have a wonderful weekend!!!


#9
If you really must keep it in your basement, and you are
concerned about confined space, you can build a leak proof dike
around it to create an area with a volume at least equal to
that of your tank. >>

Could you elaberate (sp?) on that . . .what do you mean “leak
proof dike”??? Something like a box???

Thanks for the advice!


#10
Your message about acetylene and propane scared me! If we
do indeed have a studio in our basement or house we have no
choice but to keep our tank inside. My understanding was that
acetylene tanks have a lead plug that melts in the event of a
fire-gas escapes and there is no explosion.I have never heard
about an explosion with acetylene and have seen many "leaky
regulators. Would it help to keep the window cracked in the
studio?  Thanks Jennifer Karotkin >>

What I understood from his message is that this (and other) gas
POOL at floor level . … If one has their studio in their
basement, one doesn’t usually have windows at floor level (they
are usually found at ceiling level) which wouldn’t help promote
ventiliation. Perhaps, some sort of “vaccuum” system (with the
exhaust being outdoors?) could be a solution?

I know at least 50 metalsmiths who have used this and other
gasses in their basements for YEARS without incident . . .
figures, just when I go into it full time, all the dangers show
up! : )


#11

…Could you elaberate (sp?) on that . . .what do you mean “leak
proof dike”??? Something like a box???..

If you have ever seen the really big oil or gas storage tanks,
you will notice that there is a large concrete wall around each
one. This forms a catch basin in the event of a ruptured tank.

As a permanent saet-up, if you have a concrete or dirt floor in
your basement, you could build up a concrete wall around you
tank. Just make sure that the wall is high enough so that the
area of the ‘box’ that you make is greater than the volume of the
tank you use. If you have a wood floor, you could frame out the
box with plywood and 2x3’s and line it with something leakproof
(place the 2x’s on the outside so thay don’t get in the way of
the liner). I know plumbing supply houses sell a rubber-type
material that is used under the floor of tiled showers, but that
may be overkill. Hardware stores sell plastic sheeting in
various thickness for use as vapor barriers when insulating a
house. Probably cheaper and easier to get. Just be careful
handling it, as any puncture would make the dike useless.

If you want something easier and moveable, just get a large,
heavy duty box and line it with the plastic.

Either way, if you are using plastic lining, I would suggest
placing something in the bottom of the box on top of the lining
that would prevent the tank from tearing the plastic.

Hope this helps.

Sharon Ziemek
GoldStones, Inc.


#12
    I had an experience with a leaky acetylene tank. The whole
"B" tank leaked out into the house. Several hours later I went
back in and open all the windows and turned on fans everywhere.
 The whole thing did not result in any tragedy.

G’day Another tuppence worth; If anyone gets a bad leak like
our friend I want to suggest that whatever you do, DONT switch
on any thing electrical; and that of course includes lights and
even fans. The switch may cause enough spark to set the whole
gubbins off - and look, mum, no house!

One of the bravest things I witnessed was when a big cylinder of
hydrogen leaked. It was found in one of the labs when we came to
work one morning, and there was a pale blue flame coming from the
fitting at the outlet, and the gauge, valve, etc was red-hot!
The chap who found it promptly called the Sheffield Fire Brigade,
and two of the firemen simply carried the dreadful thing - still
burning fiercely - down six flights of stairs into the
courtyard, where they let it burn itself out. They daren’t use
the lift [elevator] for obvious reasons. It wasn’t really passing
the buck (sorry, cylinder.) or was it? The chap who found it felt
that firemen are trained to deal with all fire emergencies, and
he didn’t know what to do. He only had a PhD in chemistry.
Cheers, –

        /\
       / /    John Burgess, 
      / /
     / //\    @John_Burgess2
    / / \ \
   / (___) \
  (_________)

#13
What I understood from his message is that this (and other)
gas POOL at floor level . ..  If one has their studio in their
basement, one doesn't usually have windows at floor level
(they 

Why not put a small vent in the door, close to the floor? You
would, of course, have to put in a deadbolt way up high if you
did this, so that someone couldn’t kick in the vent in the door
and let themselves in.

anne


#14

If you have ever seen the really big oil or gas storage tanks,
you will notice that there is a large concrete wall around each
one. This forms a catch basin in the event of a ruptured tank.

You could just put the tank into a large plastic trash barrel.

Rick
Richard D. Hamilton

Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com
@rick_hamilton


#15
The whole "B" tank leaked out into the house. Several hours
later I went back in and open all the windows and turned on
fans everywhere.  The whole thing did  not result in any
tragedy.

Hi Susan,

You were lucky! Switching on any electrical device could very
well have been fatal, as there is a spark created that can
ignite the gas-air-mixture. There is the old joke about the
fireman ringing at the house they were called to because gas was
leaking…

regards, Markus


#16
If you have ever seen the really big oil or gas storage tanks,
you will notice that there is a large concrete wall around each
one.  This forms a catch basin in the event of a ruptured tank.      (snip)

Tank dikes are indeed used on large oil storage tanks, but will
not help with small propane storage tanks. Propane is a liquid
while under pressure in the tank, but turns into a gas when
released at room temperature and room (atmospheric) pressure.
When liquid propane vapourizes, the gas takes up over 200 times
more space than the liquid did. So a 20 pound propane tank which
is about one cubic foot of volume will expand to over 200 cubic
feet when released as a gas.

I am still hoping to hear form people who have had gas leak
incedents in their homes.

MILT


#17

You could just put the tank into a large plastic trash barrel.

That’s what I love about this forum! You people know how to
simplify, simplify, simplify!!!

Thanks, and hope you’re enjoying your sailing.

Sharon


#18
Your message about acetylene and propane scared me! If we do
indeed have a studio in our basement or house we have no choice
but to keep our tank inside. My understanding was that acetylene
tanks have a lead plug that melts in the event of a fire-gas
escapes and there is no explosion.I have never heard about an
explosion with acetylene and have seen many "leaky regulators.
Would it help to keep the window cracked in the studio?  Thanks

Hi Jennifer K, To the rest of you scaring the living daylights
out of each other about fuel gas and oxygen. It’s about time
you learn about time: The time it take you smell natural gas,
acetylene,etc,etc,. You should have more than enough time to
turn off the tank and figure out what’s going on. You should be
sitting right next to the tank and will either smell something,
or hear something, or feel something before there’s any real
problems. This pooling of gases only takes place if you leave
them alone without shutting then off. Observe the 5/5 rule (five
minutes or five feet). I work in a shop with many people who
are aware of something in the wind in about 30 seconds (usually a
blown out torch). In my home shop where I’m alone 5/5 always.
Timing on torches to solder simple joints;

Natural gas & compressed air…cost $… flame type: dead slowclean
Natural gas & oxygenr …cost $$…flame type:meduim clean
propane & oxygen …cost$$med.-fast…flame type:clean
acetylene & oxygen … cost$$$fast…flame type:dirty
acetylene (presto lite) … cost$…flame type:slow dirty
hydrogen & oxygen … cost$$$$$…flame type: fast clean

Pick one and get busy. Jim alpine@hay.net


#19

MMMMMmmmm, I have to agree!


#20

Why not put a small vent in the door, close to the floor?

Hi Anne,

This would work if the bottom is really horizontal or has an
inclination towards the door and is dead flat, and I know of
houses that have a drain in the bottom, so propane could pool
below the foundation of the house - one spark…

regards, Markus