Abstract: At approximately 3:00 p.m. on May 23, 2003, a customer brought in a compressed gas cylinder to be filled approximately 30 minutes prior to the incident. Witness #3, the manager, put the cylinder to one side and instructed Employee #1, a part-time employee, to fill the cylinder. Witness #3 said when he returned from a delivery about 30 minutes later Employee #1 had connected the cylinder to a hose manifold and was filling the cylinder with helium. When the gauge pressure on the manifold read between 1,100 and 1,300 psi, the cylinder exploded, seriously injuring Employee #1. He said the label and markings on the dropped off cylinder were unreadable and the entire cylinder was painted black. Witnesses #2, who was not an employee, and #3 confirmed that the cylinder had been painted black and the marking were unreadable. Later a representative from a compressed gas supplier determined that the cylinder that exploded was a low pressure acetylene cylinder. Employee #1 was transported to St Francis Medical Center in Lynwood, California, where he remained at least five days with a compound fracture of his lower left leg and tendon damage to his left forearm.