PDFWAC 296-104-320

Installation—Where should the discharge from safety pressure relief devices, blow offs and drains be directed?

Discharge from safety pressure relief devices, blow offs and drains shall be directed to a safe point of discharge to prevent injury to personnel and property. Discharge lines from boilers, accumulators, or headers, with a capacity of 1,000 pounds of steam per hour or more, shall be directed outside of the building.
For hot water heater discharge lines as defined in WAC 296-104-010 that do not exceed 120 gallons or 200,000 Btu/hr input the following requirements shall be followed:
The discharge piping serving a temperature relief valve, pressure relief valve, or combination of both shall have no valves, or obstructions, or means of isolation and be provided with the following:
(1) Equal to the size of the valve outlet and shall discharge full size to the flood level of the area receiving the discharge and pointing down.
(2) Materials shall be rated at not less than the operating temperature of the system and approved for such use.
(3) Discharge pipe shall discharge independently by gravity through an air gap into the drainage system or outside of the building with the end of the pipe not exceeding 2 feet (610 mm) and not less than 6 inches (152 mm) above the ground and pointing downwards.
(4) Discharge in such a manner that does not cause personal injury or structural damage.
(5) No part of such discharge pipe shall be trapped or subject to freezing.
(6) The terminal end of the pipe shall not be threaded.
(7) Discharge from a relief valve into a water heater pan shall be prohibited.
Exception:
Where no drainage was provided, replacement water heating equipment shall only be required to provide a drain pointing downward from the relief valve to extend between 2 feet (610 mm) and 6 inches (152 mm) from the floor. No additional floor drain need be provided.
[Statutory Authority: Chapter 70.79 RCW. WSR 18-23-092, § 296-104-320, filed 11/20/18, effective 1/1/19. Statutory Authority: RCW 70.79.030, 70.79.040, 70.79.150, 70.79.290, 70.79.330, 70.79.350, and chapter 70.79 RCW. WSR 04-01-194, § 296-104-320, filed 12/24/03, effective 1/24/04; WSR 02-23-036, recodified as § 296-104-320, filed 11/13/02, effective 12/14/02. Statutory Authority: RCW 70.79.030 and 70.79.040. WSR 98-22-024, § 296-104-310, filed 10/28/98, effective 11/28/98; WSR 97-20-109, § 296-104-310, filed 9/30/97, effective 10/31/97; Part V, § 3, filed 3/23/60.]