STEAM BOILERS 125 



steam be taken from another steam pipe. The suction pipe 

 should be as straight as possible and must be air-tight. In 

 connecting up an injector, the pipes should be cleaned by 

 blowing them out with steam before making the connection, 

 "because if a small bit of dirt gets into the injector it will inter- 

 fere seriously with its operation. 



Injector Troubles. In the discussion of injector troubles as 

 given in succeeding paragraphs, the suction pipe, strainer, 

 feed-delivery pipe, and check- valve are considered as parts of 

 the injector. In searching for the cause of a trouble, therefore, 

 the suction and delivery pipes should be carefully inspected as 

 well as the injector. 



Failure to Raise Water. The causes that prevent an injector 

 from raising water are: 



1. Suction Pipe Stopped Up. This is due, generally, to a 

 clogged strainer or to the pipe itself being stopped up at some 

 point. In case the suction pipe is clogged, steam should be 

 blown back through the pipe to force out the obstruction. 



2. Leaks in Suction Pipe. This prevents the injector form- 

 ing the vacuum required to raise the water. To test the 

 suction pipe for air leaks, plug up the end and turn the full 

 steam pressure on the pipe; leaks will then be revealed by 

 the steam issuing therefrom. Have the suction pipe full of 

 water before steam is turned on, as the presence of small 

 leaks will be revealed better by water than by steam. 



3. Water in the Suction Pipe Too Hot. A leaky steam 

 valve or leaky boiler check- valve and leaky injector check- 

 valve may be the cause of hot water or steam entering the 

 source of supply and heating the water so hot that the injector 

 refuses to handle it. 



4. Obstruction in Tubes. There may be an obstruction in 

 the lifting or combining tubes; or, the spills (or openings) in 

 the tubes through which the steam and water escape to the 

 overflow may be clogged up with dirt or lime. 



Injector Primes, but Will Not Force. In some cases an 

 injector will lift water, but will not force it into the boiler; or, 

 it may force part of it into the boiler and the rest out of the 

 overflow. When it fails to force, the trouble may be due to 

 one or the other of the following causes: 

 10 



