A health physics technician (HPT) discovered that a scaler in an analytical laboratory was out of P-10 gas (90%Ar and 10% CH4). The HPT went to the building where auxiliary gas cylinders are stored. He located a P-10 gas cylinder and turned to search for a hand-cart. There were no hand-carts present, and the technician had to get one from another room. When he returned to the cylinder storage area, he loaded the wrong cylinder. It contained hydrogen gas instead, however, the two cylinders were next to each other and they were basically identical. The empty cylinder was then replaced by the full one and the scaler was purged for several minutes before it was used. The alpha channel worked well, however, the beta channel did not respond. An instrument technician was contacted to identify any possible electronic failures in the instrument and he discovered that the gas was hydrogen rather than the P-10 gas. The hydrogen cylinder was shut off, disconnected and removed. The correct P-10 cylinder was located and connected to the scaler.
All chemicals, including gases, should be clearly labeled and expiration dates (if applicable) identified. Incidents are more common when incompatible chemicals are mixed or when chemicals are stored/transferred using incompatible equipment. Personnel should ensure that labels are read and understood prior to mixing, dispensing, or transferring chemicals.