1. (1) On all boilers, except electric steam boilers having a normal water content not exceeding 100 gallons, and those used for traction and/or portable purposes, when the allowable working pressure exceeds 100 psi, each bottom blowoff pipe shall have two slow-opening valves, or one quick-opening valve or cock at the boiler nozzle followed by a slow-opening valve. All valves shall comply with section 14-9.28(b)(4) and (5) of this Subpart.
2. (2) By “slow-opening valve” is meant one which requires at least five 360-degree turns of the operating mechanism to change from full-closed to full-opening, and vice versa.
3. (3) On a boiler having multiple blowoff pipes, a single master valve may be placed on the common blowoff pipe from the boiler, in which case only one valve on each individual blowoff is required. In this case either the master valve or the individual valve or cocks must be of the slow-opening type.
4. (4) Two independent slow-opening valves, or a slow opening valve and a quick-opening valve, or a cock may be combined in one body provided the combined fitting is the equivalent of two independent slow-opening valves, or a slow-opening valve and a quick-opening valve or a cock so that the failure of one to operate could not affect the operation of the other.

5. (5) All water walls and water screens which do not drain back into the boiler and all integral economizers shall be equipped with drain or blowoff valves conforming with the requirements of subdivisions (a) and (b) of this section and also of sections 14-9.27(b) and 14-9.28(a) of this Subpart.

   (b)

6. (1) The bottom blowoff pipes of every traction and/or portable boiler shall have at least one slow- or quick-opening blowoff valve or cock conforming to the requirements of ASME.
7. (2) Only one blowoff valve, which shall be of a slow-opening type, is required on forced circulation and electric steam boilers having a normal water content not exceeding 100 gallons.
8. (c) A bottom blowoff pipe when exposed to direct furnace heat shall be protected by firebrick, or other heat-resisting material, so arranged that the pipe may be inspected.
9. (d) An opening in the boiler setting for a blowoff pipe shall be arranged to provide free expansion and contraction.
10. (e) Blowoff pipes shall be located so as to prevent scalding.
11. (f) Bottom blowoff valves shall be tested daily when the boiler is in operation.

(a)