Nevada Administrative Code
Chapter 455C - Boilers, Elevators and Pressure Vessels
BOILERS AND PRESSURE VESSELS
Boilers
Section 455C.256 - Feeding

1. Each boiler must have a supply of feed water that will allow it to be fed at any time while under pressure.

2. A boiler having more than 500 square feet of water heating surface must have at least two means of feeding water, one of which must be a feed pump. A source of feed directly from water mains at a pressure of 6 percent greater than the set pressure of the safety valve with the highest setting may be used as one of the means of feeding water. Boilers fired by gaseous, liquid or solid fuel in suspension may be equipped with a single means of feeding water if means are furnished for the shutoff of heat before the level of water reaches the lowest safe level.

3. The feed water must be introduced into the boiler in such a manner that it will not be discharged close to riveted joints of the shell or furnace sheets, directly against the surfaces exposed to products of combustion or to direct radiation from the fire. The feed piping to the boiler must be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler. If two or more boilers are fed from a common source, there must also be a stop valve on the branch to each boiler between the check valve and source of supply. If a globe valve is used on feed piping, the inlet must be under the disc of the valve.

4. In all cases where returns are fed back to the boiler by gravity, there must be a check valve and stop valve in each return line. The stop valve must be placed between the boiler and the check valve, and both must be located as close to the boiler as is practicable.