Well, in the FWIW column.
Here is a website that does a pretty thorough job of explaining UN spec steel drums. I am sure there are others / better / worse / whatever out there.
http://www.myerscontainer.com/UN%20I...ection%201.pdf
Some basic salient points I thought I would add in the short version.
Find the UN marking on the drum in question, it will have that funny little symbol at the front.
If you see an S in that string, then the drum is designed for solids, not liquids.
If you go find the "packing group" an X, Y or Z in that string (spelled out in the attachment, an X is the better of the 3, generally translating into thicker stronger safer.
If you go to page 24, it will explain show how to check test pressures, which they are mostly concerned with the vapor pressure of the products contained, but again, as a general statement, higher numbers stronger drum.
What I thought I would add.
When reconditioning steel drums (that are suitable) often times the final check is a pressure check, with air, and those pressure testers are usually operated between 2 and 7 PSI.
Is it safe to pressurize an old, used, non rated drum? Not in my opinion, it is not worth the risk.
Then again, I don't run PVC airlines in my shop either, and plenty of folks do and it works fine for them.
All the safety stuff really boils down to "are you willing to accept the risk"
Personally, I have had tanks and drums fail on me at different points, and different circumstances, and have had to deal with failures that others have induced. It has the potential to be catastrophic.
If I was going to do it, I would certainly insure that I had a pressure releif valve of some type in the system so that when things went wrong, I had a modicum of control there.
My personal stuff, I have an electric pump in a 55 gallon drum.
My work stuff, seems like we have about one of everything
As a side note, yesterday, had a fun one, watching a class being given, and the young student did not get a sampling coupler (much like an air or hydrualic coupler) properly latched on the back of the fuel truck. 100
GPM over all flow, neck down into a 3/8" tube makes a heck of a mess, and is inconvienent at best when the person on the deadman freezes up, and the guy who opened the valve jumps away...
Little bit of appropriate NCO type voice inflection went a long way to fixing the problem though.