THE FEED WATER 29 



valve "sticks" and will not close, a very slight tap may 

 cause it to "seat," but if this does not, close the valve be- 

 tween it and boiler, then take off the cap and remove dirt 

 or scale that may be preventing it from closing tightly. If 

 no foreign matter be found, examine the valve and seat to 

 determine if the contact surfaces be perfect. If scale be 

 found adhering to either, it should be removed, but if it be 

 "pitted," regrinding is necessary. Although a slight tap 

 will often cause a check- valve to seat, it is poor practice to 

 constantly or violently hammer the valve, as the seat may 

 be distorted, and the entire valve ruined thereby. Many 

 valves are also distorted and ruined because a wrench 

 has been used on one end while screwing a pipe into the 

 other. Many valves are burst during cold weather by 

 frost. To prevent this, the angle valve near boiler must 

 be closed and the check-valve and pipe drained. 



Regrinding Check-Valves. Many engineers discard 

 leaky valves as worthless, in ignorance of the ease with 

 which they may be re-ground. The swing check is easily 

 re-ground without disconnecting it from the pipe. To re- 

 grind, unscrew angle plug, put a little flour of emery, mixed 

 with oil or soap, on the bottom of valve and turn it back 

 and forth with a screw driver until the contact surfaces 

 are perfect. 



Feed-Water Heaters. A feed-water heater heats the 

 feed water delivered by the pump, by passing it over sur- 

 faces heated with exhaust steam from the engine. In this 



