Nikom Chimnok on sun 5 mar 00
I was happy to read the story below, because it goes to show that you CAN
heat gas tanks and live to tell about it. In fact you can heat them again
and again, and live to be a doddering old geezer. It isn't the safest thing
in the world to do, but you CAN get away with it, especially if you're smart
and attentive.
I first saw propane tanks being heated in Alaska, where people start their
cars at 60 below with weed burners. Crankcase oil at this temperature is
congealed, and batteries have little power, so standard practice is to keep
a gas tank in the house overnight, then drag it out in the morning and stick
a weed burner into a length of stovepipe with an elbow that exits beneath
the oil pan. But if the tank is almost empty, it'll chill right down till
the fire goes out, so you pull the weed burner out and warm the tank till
the flame is steady again, then resume heating the oil pan. This works.
A much safer solution is to have a heated garage, and this is what
university professors do. Wild young men who live in shacks, however, do
not. Oddly enough, I never heard of anyone dying this way, tho numerous
radiator hoses have been burnt.
And now I work at a factory in Thailand, where we fire every other day a
kiln that uses 6 tanks of gas per firing. Three tanks are manifolded
together, and they sit in a tank of water with a gas cookstove beneath,
warming the water. Five years now, and no accidents.
But to get a wider perspective, I interviewed our Number One Fireman, who
hails from Lampang, a pottery city in Northern Thailand where there are 200
factories with 10000 workers making slipcast junk for Hallmark and Walmart
and outfits like that. I asked him if he'd ever heard of an accident. "Yes,"
he answered, "but all the people got out alive."
He said the problem in Lampang is big big kilns, where they're heating 10
and 20 tanks at a time: too many to watch. The water gets too hot, the
pressure gets too high, and the regulator starts leaking; the gas then is
ignited by the flame underneath the water tank. This is not too
serious--just turn off the tank supplying the burner under the tank, and the
fire will soon burn itself out.
The big danger is when somebody forgets to open the valve on one of the
tanks. The rupture of a full tank of gas is a serious matter: will take the
roof off and knock the kiln down. If nobody dies it's just luck.
But for the most part, 99+% of the time, the system works fine. We have a
rule: watch the pressure gauge. We have two gauges, one before the regulator
and one after. The one before tells what the tank pressure is. Since a fresh
tank of gas reads 100 psi, we assume that's safe. When heating the water, we
turn off the gas supplying the heater at about 90 psi: margin of safety.
When trading out empty tanks for full ones, we dump hot water and add cool,
because the full ones could be over-pressurized if the water is too hot. We
practice preventative maintenance too, in that every year I go to town and
purchase new rubber gaskets for the connectors where the hoses screw into
the tanks, whether the old ones need replacing or not.
Of course we check from time to time to make sure there are no leaks. The
stern safety warning, "IF there is a leak..." has no meaning. There is
either a leak or there is not a leak, and it's easy to find that out with a
cigarette lighter (or sudsy water, if you are afraid of cigarette lighters.)
We fire in a huge open barn of a building, so there's no possibility of
pooling gas, unlike in tight little rooms. So small leaks are not a
problem--we don't stop the firing because of one. Fix them between firings.
Heating water is a lot safer than directly heating the tank, because the
water is never going to get much above the boiling point, while playing a
flame on the tank could turn the steel red, if you were stupid enough.
Please let me say that I have no objection to safer systems, either--it's
just that none are easily available here. There are no big tanks for rent.
I've recommended to the management that they buy a tank the size they have
at the service station where we get our 48 KG tanks filled, but they reject
this as too expensive. It'd be nice to have liquid burners, or in-line
evaporators with electric heaters, such as I hear are widely used in Japan,
but we don't have any of them either, so we get by. And get by pretty well,
too--no one here has ever been harmed by gas, while scores I know have died
in traffic accidents, of AIDS, electrical shocks, lung cancer and cirrhosis
of the liver.
Tho I have lived amongst fatalists for a long time, I have not become one.
Nor, while heating gas tanks do I feel exactly like a cowboy. Instead, I
feel more like Werner von Braun, I believe it was, about whom I once read
this story: In one of the early rocket launches, at about 2 minutes before
IGNITION, somebody noticed a puddle on the ground beneath the rocket. While
everyone else, assuming a leak of some kind, was yelling ABORT ABORT ABORT,
Dr. von Braun made a mad dash, ducked beneath the rocket, stuck his finger
in the puddle, stuck his finger in his mouth, pulled it out and yelled
"Condensation!", simultaneously giving them a thumbs up. The launch was on.
I'm no rocket scientist, but I know how to heat a gas tank. If you're
careless and stupid (ha ha, the careless and stupid are always the last to
know it!) you shouldn't try it. But if you understand the basics of gas
behavior, and carefully attend to what you are doing, you can get away with
heating gas tanks all your life. It's less dangerous than driving cars,
because you are in complete control, and never need to worry about drunks
smashing into you.
So much on the subject of heating gas tanks.
Nikom
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At 18:15 3/3/00 EST, you wrote:
>----------------------------Original message----------------------------
, at 4
>am...dutifully armed with my propane torch I head out to apply gentle heat
>to the bottom of that tamk. I know my hands shook , and as I lay out there
>trying to apply some heat to this tank my life flashed before my
>eyes,,literally,,,,,I even remember talking to myself out loud,,,and said
>"What the (expletive deleted) are you doing this for?,,,you are a crazy
>women."
>No I did not blow myself up,,,,and the firing got done,,,,,and my kids still
>have a mom...
>Paul Lewing wrote:
>
>> ----------------------------Original message----------------------------
>> I once had a studio partner who, after the water bath didn't work any
>> more, would warm the tank up by pulling a burner on a flexible hose out
>> of the kiln and pointing it at the tank. This is a good way to make
>> yourself eligible for the Darwin Awards. Those are given to people who
>> take themselves out of the gene pool in particularly spectacular and
>> foolish ways.
>> Paul Lewing, Seattle
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