Iowa Code r. 875-92.11 - Blowoff connection requirements

This rule applies to power boilers installed prior to July 1, 1983. Each boiler will have a blowoff pipe fitted with valve or cock, in direct connection with the lowest water space practicable.

(1) When the maximum allowable working pressure exceeds 125 psig, the blowoff pipe will be at least schedule 80 from the boiler to the valve or valves and will run full size without reducers or bushings. Galvanized materials will not be used.
(2) All fittings between the boiler and valve will be steel or at least schedule 80 fittings of bronze, brass, malleable iron, or cast iron, all of which will be suitable for the pressure and temperature. In case of replacement of pipe or fittings in the blowoff lines, as specified in this paragraph, they will be installed in accordance with the rules of new installations.
(3) When the maximum allowable working pressure exceeds 125 psig, each bottom blowoff pipe will be fitted with at least a 250-pound standard valve or cock. Two valves, or a valve and a cock, should be used on each blowoff.
(4) When exposed to direct furnace heat, a bottom blowoff pipe will be protected by firebrick or other heat resisting material so arranged that the pipe may be inspected.
(5) An opening in the boiler setting for a blowoff pipe will be arranged to provide for free expansion and contraction.

Notes

Iowa Code r. 875-92.11
Adopted by IAB February 19, 2025/Volume XLVII, Number 17, effective 3/26/2025

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