Federal regulation 29 CFR 1910.147 of the Occupational Safety and Health Administration (OSHA) details safety requirements for the control of hazardous energy during “… theservicing and maintenance of machines and equipment in which the unexpected … startup … could cause injury …” Here are a few other highlights from the regulation:
ENERGY SOURCE. “Any source of electrical, mechanical,hydraulic, pneumatic, thermal, or other energy.”
LOCKOUT DEVICE. “A device that utilizes a positive means such as a lock, whether key or combination, to hold an energy isolating device in the safe position …”
PURPOSE. “This section requires employers to establish a program and utilize procedures for affixing appropriate lockout devices . . . to prevent unexpected energization, startup or release of stored energy …”
TIMING. “After October 31, 1989, whenever major replacement, repair, renovation or modification of machines or equipment are installed, energy isolating devices for such machines or equipment shall be designed to accept a lockout device.”
In short, each piece of equipment must have a shutoff valve to isolate the equipment from its air supply. The shutoff valve must be lockable in the closed position so that it cannot inadvertently be opened. When closed the shutoff valve must have an exhaust port to exhaust downstream pressurized air.
When actuated, valves with the delayed-pressure buildup (DPB) feature allow a gradual buildup of downstream air pressure. This allows cylinders and other work elements to move slowly and more safely into their normal working positions. After downstream pressure has reached a certain level the valve opens fully and downstream pressure is at its maximum level. The DPB function is achieved by requiring the initial flow of air to pass through a restricted orifice so that the Some of the DPB valves described below also have a lockout control, so that they serve the double functions of delayed-pressure-buildup and lockout control.