>>136091You're looking for retest stamps on the crown of the cylinder.
At the minimum there'll be a DOT rating, manufacturer's stamp (month and year), a serial number, and the manufacturer's name.
"DOT 3AL3000" is a 3000PSI aluminum cylinder. Service pressure is indicated here.
"Luxfer" and "Catalina" are two popular aluminum cylinder mfgr's. Catalina puts a little stylized "CL" logo between the month/year stamp.
Serial number is usually 6-10 characters long, some begin with an alpha character.
Retests look similar to manufacturer stamps, except there's a "RIN" number between month and year, 4 characters in a 2x2 stamp.
A "+" means it's good for 10% overfill above service pressure. (Service pressure is always lower than test pressure.)
A star means the cyliner's good for 10-year retest, as opposed to 5-years without the star.
"UT" or "UE" means the cylinder was ultrasonically tested, instead of the traditional hydro test.
Source: worked at a company that developed a product to ultrasonically test these gas cylinders.
So, look for the latest retest stamp. If it's less than 5 years ago, it's in test. If there's a star, less than 10 years ago it's good.
