Feeding and feedwater piping

1. Every miniature boiler must be provided with at least one feed pump or other mechanical feeding device except if the following conditions exist: a. If the boiler is connected to a water main or system having sufficient pressure to feed the boiler at any time while under pressure. b. If the fuel burned is such that all heat input can be discontinued instantaneously by the operation of a valve, cock, or switch, thereby permitting the boiler pressure to be quickly lowered to a point where water can be introduced from the connection of the water main. c. If the boiler is operated without extraction of steam (closed system) in which case the boiler is filled, when cold, through the connection or opening provided in accordance with the following rule. 2. Each miniature boiler must be fitted with a feedwater connection that may not be less than one-half inch [12.7 millimeter] iron pipe size. The feed piping must be provided with a check valve near the boiler and a valve or check between the check valve and the boiler. 3. Feedwater may be introduced through the blowoff connection if the boiler is operated without extraction of steam (closed system). 4. Feedwater may not be introduced through the water column or gauge glass connections while the boiler is under pressure.