hi agian, my teacher has asked me to write another question on this forum, ok why if your not suppose to go over 15psi working pressure on a acetylene tank, then why do they have it were u can go over 15psi, u would think if ur not suppose to go over 15psy they would make it wer u cant....... hope for ur answers
I'll take a shot at this one!
I assume it gives you the allowance because 15 psi is a gauge pressure measurement. Absolute pressure = Gauge pressure + Atmospheric pressure.
Atmospheric pressure is estimated at 14.7 psi - but changes with elevation and temperature surroundings.
If they could make a gauge that reads the gauge and absolute pressure, then perhaps they could design a pressure adjusting screw that would limit at either 15 psi gauge, or 29.7 psi absolute. I'd assume this would be quite expensive.
Just a thought,
vicki
Raw Acetylene will explode, detonate, auto ignite or decompose violently (how ever you want to say it) at pressures greater than 15PSI.
When Acetylene is put in to the cylinders it is mixed with Acetone to help stabilize it. That allows you a bit more lead way.
yes, my teacher has told the class that acetylene is unstable at pressures above 15psi.
Ron has the right idea, it's unstable at pressures over 15psi.
John Wright
If you have single stage regulators the pressure on the high side has an effect on the low side. If you set the regulator to 15 psi on a new tank it would read much less as the tank approached empty. You would compensate for this by adjusting the regulator to keep the pressure correct. If you then changed to a new tank without readjusting (you should back off the adjusting screw completely when changing to a new tank) it would read over 15 psi but you needed the adjustment space so you could empty the previous tank. Dual stage regulators are much less effected.
As the regulator wears you might need some adjustment space to compensate.
If you use the regulator for some other fuel gas (like propane) the 15psi limit doesn't apply.
Bill
I believe the regulators are capable of delivering more than 15 psi because the actual adjustment screw positions can vary with the tank pressures. Even though 2 stage regulators smooth out the pressures so that adjustment is not needed very often you could have a regulator set for a bottle that is almost empty and then not remember to back off the screw when changing to a full bottle. Then you could have pressures over 15 psi.
Secondly, the regulators can be used for other gases, such as MAPP, that can be used at full cylinder pressure.
Chet Guilford
HEY ALL,
all the dangers of acetylene had made me a year ago switch to MAPP.
my main reason is my torchs are carried in my trailer and if someone crashed into it, the acetylene could explode from just shock. the MAPP goes like 4x farther and the cylinder is 100x lighter (exxagerated somewhat)
rich
Hey Rich, do you use MAPP for welding or just for cutting. I know that alot of people use it for cutting, but I'm curious how well MAPP works for welding.
hey hooks,
i use it for cutting, brazing and heating. some say it can weld, some say not. i personally have no need to gas weld. the regulator is the same, you just need the "T" grade hose and tips.
rich
MAAP gas is actually hotter in terms of total BTU's produced, because of the hotter secondary flame. This makes it better for cutting and heating, while the hotter cone of the acetylene flame makes it better for welding because of the hotter primary flame (inner cone).
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