Section 408.4296. Bottom blowoffs or drain valves.

(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                 Blowoff Safety or Relief Valve Capacity                         Valves

Lb. of Steam per Hour              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.

History: 1979 AC.