An explosion and fire hazard was encountered. The design of the Wood's metal thermal safety device on a cyclopropane cylinder was found to contribute to human carelessness that endangered me and several bystanders. Alternative thermal safety devices that are superior in design and avoid this occurrence are already in use. Since a previous report in 1968 no definitive action on eliminating this hazard has been taken by the distributors of flammable anesthetic gases. Until this design fault is eliminated from distribution all personnel and patients are at potential risk.