Safety appliances: Capacity.

1. The capacity of a safety valve that is designed primarily for steam or vapor service must be rated in pounds per hour. 2. The capacity of a relief valve that is designed primarily for liquid service must be rated in British thermal units per hour. The capacity of a relief valve used for liquid service with cold water may be rated in gallons per hour. 3. The capacity of a safety relief valve that is designed for use in steam or vapor and liquid service must be rated in pounds per hour when used for steam or vapor service and in British thermal units per hour when used for heated liquid service. 4. A pressure relief valve that is used for air service must be rated in PSIG and square cubic feet per minute.