All ammonia refrigeration systems containing more than 100 pounds (45.36 kg) of ammonia shall be provided with a hand-operated emergency valve. Such device shall be connected to the low side of the refrigeration system and be located where the emergency valve is readily available for Fire Department use. Valves shall be identified and operation for the use of the emergency valve shall be provided at the location of the valve. Discharge from above hand operated emergency valve shall be into a mixing chamber made from ASTM Schedule 40 black iron pipe with weld cap ends. The mixing chamber shall have a minimum length of 72 inches (1.288 m) and a nominal pipes size as found in column "A" of Table 18-28-1107. Dumped refrigerants shall flow into the mixing chamber through an inlet tube extending longitudinally into the mixing chamber for a minimum length of 64 inches (1.6256 m). The inlet tube shall be made of ASTM Schedule 40 black iron pipe and shall have a nominal pipe size as found in column "D" of Table 18-28-1107. The downstream end of the inlet tube shall be capped with a weld cap fitting and the sides of the inlet tube near the weld cap fitting on the downstream end shall be perforated with one-quarter (1/4 inch) (12.2 mm) drilled holes spaced on 1-inch (25.4 mm) centers and arranged in rows. The minimum number of perforations in the inlet pipe shall relate to the system refrigerant charge in accordance with column "C" of Table 18-28-1107. Flushing water shall be supplied through a 3 inch (76.2 mm) Fire Department approved cast iron Siamese fitting, or equivalent with two flappers, welded into the side of the mixing chamber on a 45-degree angle to its longitudinal axis near the inlet end.
The effluent mixture of water and refrigerant shall flow longitudinally out of the discharge end of the mixing chamber through an ASTM Schedule 40 black iron pipe welded into the end cap of the chamber. The nominal pipe size of the discharge pipe shall be as found in column "B" of Table 18-28-1107. The discharge pipe shall connect to the city sewer through a solid connection without intervening valves or traps.
Pounds (lbs.) of Ammonia | A | B | C | D |
100 – 1,000 | 6 inches | 3 inches | 144 | 2 inches |
1,001 – 2,000 | 6 inches | 3 inches | 216 | 3 inches |
2,001 – 5,000 | 6 inches | 4 inches | 216 | 3 inches |
5,001 – 10,000 | 8 inches | 4 inches | 216 | 3 inches |
(Amend Coun. J. 11-8-12, p. 38872, § 326; Amend Coun. J. 11-9-16, p. 36266, § 36)