Q. Has the independent pump sufficient capacity to supply the boiler with water under all conditions?
A. Yes, always, when running at a reasonable speed.
Q. Why should an injector be furnished if the pump will supply the boiler?
A. Many times through carelessness or otherwise the pump is prevented from working by dirt, straw, chips and other obstructions which find their way into the pump and hold the valves from their seats. In this case it is necessary to take the pump apart and remove the obstructions wherever found, which would necessitate stopping the engine and allowing the steam to go down, involving a large loss of time. Whereas if the engine is also supplied with an injector, should the pump fail, the injector can immediately be started and the pump examined at leisure without loss of time and avoiding all danger of explosion.
Q. Should the supply of feed water be continuous while the engine is running?
A. Yes. Gauge the speed of the independent pump so that it will furnish the required amount of water to the boiler. Regulate the feed of a cross-head pump, by the suction valve. By so doing, the boiler steams easier, the flues are not so liable to leak, and a uniform steam pressure can be easily maintained more economically.
Q. How is a boiler supplied when engine is in motion?
A. By the independent or cross-head pump.
Q. When should the injector be used in preference to the independent pump?