This  feed  water  heating  arrangement  is,  in  basic  principles  of
construction  and  operation,  similar  to  the  appliance  previously  de-
scribed, and  differs  only  in  detail.  The  arrangement  of  the  va-
rious units  of  the  system  is  shown  in  Fig.  203.  It  may  be  seen
from  the  illustration  that  the  spray  valve  delivers  the  feed  water
to  the  boiler  at  its  highest  point,  in  the  dome.  By  this  means  the
feed  water  reaches  the  water  surface  of  the  boiler  at  practically
the  steam  temperature,  and  secures  increased  efficiency  and  de-
creased upkeep  of  the  boiler,  due  to  uniformity  of  temperature
maintained.
THE  LOCOMOTIVE   UP  TO  DATE


485


Without  this  valve,  shown  in  Fig.  204,  the  heater  installa-
tion would  be  handicapped  by  the  fact  that  the  water  fed  to  the
boiler  when  the  engine  is  standing  would  be  comparatively  cold.
When  chalky  waters  are  prevalent,  the  heating  of  the  feed  water
to  the  steam  temperature  has  also  a  pronounced  effect  on  the
character  of  the  scale,  which  is  deposited  as  a  fine  sludge,  and
may  be  readily  washed  out..
Fig.  203.
Names  of  Parts  as  Applied.
A  Heater  F  Pump  Discharge

B  Pump  G  Discharge  from  Heater

C  Spray  Valve  H  Pump  Steam

D  Exhaust  Steam  to  Heater  J   Pump  Exhaust
E  Pump  Suction

The  body  of  the  valve  is  of  gunmetal,  the  spindle  of  steel,
and  the  valve  and  seat  of  monel  metal.  The  valve  is  so  con-
structed as  to  be  easily  accessible  for  examination  at  any  time.
The  Pump.
