Abstract: On May 10, 2008, an employee was working at a facility operated by a manufacturer or processor of prepared foods. He was assisting a coworker in shutting down and disassembling the facility's Depot #4 so that it could be cleaned. As part of the process, he removed a Definox brand control valve unit from the production line. This valve had an internal coil spring that closed the valve. Compressed air from an external supply overrode the spring force to hold the valve open. He held the valve with his left hand, placing his left thumb between the seal and the partially opened butterfly. As he turned, holding this unit in his hand, the flexible air line supplying compressed air to the valve came off its socket. The butterfly valve shut due to the internal coil spring tension. This action amputated approximately 0.5 inches of his left thumb, including bone loss. Employee #1 was admitted to Washington Hospital, in Oakland, CA, where he was treated and discharged on the same day, May 10, 2008.