N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 4-5.3

Current through Register Vol. 46, No. 50, December 11, 2024

Section 4-5.3 - Relief valves for low pressure hot water boilers

(a) Capacity. A low pressure hot water boiler shall include a relief valve or valves of a capacity such that with the heat generating equipment operating at maximum the pressure cannot rise more than 20 percent above the maximum allowable working pressure if that is 30 psi gage or less, nor more than 10 percent if it is more than 30 psi gage. If the steam relieving capacity in pounds per hour is calculated, it shall be determined by dividing by 1,000 the maximum Btu output at the boiler nozzle obtainable from the heat generating equipment, or by multiplying the square feet of heating surface by the values given in the table in section 4-5.2(a) of this Subpart.

(b) Increased capacity. When operating conditions are changed or additional boiler heating service is installed the valve capacity shall be checked and increased if necessary to meet the new conditions. Necessary additional valves may be installed on the outlet piping, providing there is no intervening valve nor other branching pipes between the additional valves and the boiler.

(c) Accumulation test. If the total capacity of relief valves is not otherwise ascertained they shall be subjected to an accumulation test.

(d) Type. Required relief valves shall be of the valve. The seats and disks of relief valves shall be of material suitable to resist corrosion. No materials likely to fail due to deterioration or vulcanization when subjected to any temperature, not exceeding 275° F. shall be used for any part.

(e) Setting. One required relief valve shall be set to relieve at a pressure at or below the maximum allowable working pressure of the boiler and so arranged that it cannot be reset to relieve at a pressure higher than the maximum allowable working pressure of the boiler. Any additional valve or valves may be set to relieve at pressures not exceeding by more than 20 percent the lowest pressure to which any other valve is set.

(f) Size. No required relief valve shall be smaller than 3/4 inch nor larger than 41/2 inch standard pipe size. The inlet opening shall have an inside diameter equal to or greater than the seat diameter. In no case shall the minimum opening through any part of the valve be less than 1/4 inch diameter or its equivalent area.

(g) Lifting device. Each relief valve shall have a substantial device which will positively lift the disk from its seat at least 1/16 inch when there is no pressure on the boiler.

N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 4-5.3