Mich. Admin. Code R. 408.4296 - Bottom blowoffs or drain valves

Rule 296.

(1) Each boiler shall have a bottom blowoff or drain pipe connection fitted with a valve or cock connected with the lowest water space practicable, with the minimum size of blowoff piping and valves as shown in table 296.

Table 296

Size of Bottom Blowoff Piping and Valves

Minimum Required Safety or Relief Valve Capacity Lb. of Steam per Hour Blowoff Valves Size, Inches
Up to 500 3/4
501 to 1,250 1
1,251 to 2,500 1 1/4
2,501 to 6,000 1 1/2
6,001 and larger 2

To determine the discharge capacity of relief valves in terms of Btu, the relieving capacity in pounds of steam per hour is multiplied by 1,000.

(2) Any discharge piping connected to bottom blowoff and/or bottom drain connection shall be full size to the point of discharge.


Mich. Admin. Code R. 408.4296
1979 AC

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