Compressed Gas Cylinder Codes and Markings Guide - By Myles TenBroeck 
 
PSI-PCI Inc. has compiled a very handy reference guide to help indentify the cylinders you are working on. Codes and markings can be tricky, this reference helps spell it out. Includes over 50 years of manufactures markings, hydrostatic test information, and how to read your cylinders. A must have for any indivual performing visual inspections on cylinders.