Acetylene Pressure v. Temperature.

[Shade Tree Welder]

There was a claim on WeldingWeb.com that Acetylene Pressure in a full tank will drop to zero at -7°F. So knowing different but not sure of the data and unable to find such date online quickly. And the low temperature being -4°F here this morning. I have collected some data. The 28°F, data points were collected a few days ago. Both low temp readings were taken ~6AM before dawn with my regulator, which has not been recently calibrated but was sufficient for this experiment. My cylinders are stored outside on the Northeast corner of my shop. Both cylinders are as filled by my LWS.

............ #4 Cylinder ......... #5 Cylinder
60°F .......... 235 ................... 225
28°F .......... 170 ................... 150
-4°F .......... 135 ................... 110

Just FYI for everyone.

So even though the pressure and ability for the cylinder to supply a known CFH of acetylene has dropped, it is not zero and even at very cold temperatures you can still get ~1/2 of the performance of a warm tank.

PS. Pressures are in psig.

[GWIZ]

Acetylene.
The boiling point is (minus) -84 C = -119º F

So at minus -119º F, I would say your bottle would be close to zero pressure.
BUT I don't know how the acetone in the bottle will effect the pressure.

http://physchem.ox.ac.uk/MSDS/AC/acetylene.html

Acetone.
http://www.ehs.utoronto.ca/Resources...1/whmis11c.htm

[USMCPOP]

Well, I checked a copy of The Horseless Age (June 20, 1900 edition), and that said "Again, acetylene can be produced and satisfactorily used at almost any temperature, while gasoline requires heating in cold weather." They were talking about headlamps, LOL. Also about running a car on it

http://books.google.com/books?id=wQo...LF7A#PPP373,M1

Here's an acetylene vapor pressure curve. http://encyclopedia.airliquide.com/i...r_Pressure.GIF

Unfortunately, the numbers didn't correlate, presumably because this was pure acetylene and not dissolved in acetone. I came up with about twice the pressure you did at -4. Oh well.

This is a pretty fascinating passage from an old book: http://books.google.com/books?id=RTE...GH0CI9-nXOSSdc