162 MARKET DAIRYING 



Care of Injector. An injector will become coated 

 with sediment or scale the same as the boiler and must, 

 therefore, be frequently cleaned. This is best done by 

 immersing it in a solution of one part muriatic acid and 

 ten parts water. Allow to remain in this solution until 

 the scale becomes soft enough to permit washing out. A 

 clean injector rarely causes trouble but if trouble does 

 occur it may be due to : (i) low steam pressure; (2) too 

 hot water; (3) leaks in pipes and injector; (4) clogging 

 of water pipe; (5) wet steam; (6) poor working condi- 

 tion of check and overflow valves; (7) clogging of feed 

 pipe where it enters the boiler. 



The injector is commonly used to feed water into the 

 boiler because it is cheap and simple, and occupies little 

 space. 



Pumps. There are two kinds; (i) those run with 

 steam directly, and (2) those run by the engine. The 

 latter is the more economical and handles hot water with 

 less trouble. It has one disadvantage, however, and that 

 is it does not work unless the engine is running. With 

 good pumps, especially those run by the engine, good 

 work may be expected when the feed water has been heat- 

 ed to 200° F. with the exhaust steam from the engine. 

 With the injector such high temperatures are not per- 

 missible, hence the greater economy of the pump. The 

 great saving of fuel by feedmg water hot into the boiler 

 is illustrated by experiments made by Jacobus which 

 show that with a direct acting pump 12.1% fuel is saved 

 by heating the feed water from 60° to 200° before pump- 

 ing it into the boiler. With injectors the feed water used 

 usually has a temperature of about 60° F. 



Steam. Water is practically a non-conductor of heat. 

 This means that it cannot conduct its heat to its neighbor- 



