2 . The steam supply line from the boiler
3 . The water overflow line
4. The water supply line from the reservoir
The controls for the injector (fig. 1-13) include the
A. Steam supply valve
B. Water supply valve
C. Discharge valve to the boiler
D. Check valve in the discharge line
As you might expect. some degree of skill is needed
to start the injector. After the injector begins to operate.
however, it continues automatically until shutdown by
When starting the injector. first open the water
supply valve (fig. 1-13B) about one full turn.
quickly turn the steam supply valve (fig. 1-13A) all the
way open. At this point, steam rushes into the combining
tube of the injector As the steam speeds past the water
supply opening. it creates a suction that draws water
through the opening into the combining tube. Water and
steam are now mixed together inside the injector and the
pressure opens a valve that leads to the boiler.
Meanwhile. there is an excess of water in the injector; this
excess is discharged through the overflow valve. As the
nest step of the procedure, slowly turn the water supply
valve (fig. 1-13B) toward the closed position until the
overflow stops. The overflow valve has now closed and
all of the water being picked up from the supply line is
going into the boiler. Remember, this feedwater system
is used on boilers only as a standby method for feeding
The water supply should not be hotter than 120°F for
the injector to operate. When several unsuccessful
attempts are made to operate the injector. it will become
very hot and cannot be made to prime. When you should
encounter this problem. pour cold water over the injector
until it is cool enough to draw water from the supply when
the steam valve is opened.
HANDHOLES AND MANHOLES
Handholds and manholes provide maintenance
personnel access into a boiler to inspect and clean it
internally as needed. These handholds and manholes will
be covered in depth when boiler maintenance is
discussed later in this volume.
Figure 1-14 provides a graphic presentation of
important boiler accessories. Refer to it as you study the
table 1-2 which gives a brief description of each
accessory, its location, and function.
Learning Objective: Identify the automatic controls
commonly used on boilers and describe the function of
Automatic controls are a big asset since they reduce
manual control of the furnace. boilers. and auxiliary
equipment. For this reason. Utilitiesman personnel
should be able to recognize and understand the basic
operations of different types of boiler operating controls.
The types of controls the Utilitiesman should become
familiar with are as follows: float. pressure, combustion.
flame failure. and operation controls.
The float in a boiler control works on the same basic
principle as the float in a flush-tank type of water closet.
Float, or level, control depends on the level of fluid in a
tank or boiler to indicate the balance between the flow out
of and the flow into the equipment and to operate a
controller to restore the balance.
A float is often used to measure the change in fluid
level and to operate the controlled valve to restore the
balance. It may be arranged to increase the flow when the
fluid level drops. Figure 1-15 shows one of the methods
used to accomplish this. Here, the float is connected to the
Q9. Blowdown valves are installed at what location in
Q10. How often should the fusible plugs in a boiler be
The two connections to the boiler of a water
column are at what locations?
Q12. What are the three types of water level controls
most often encountered by Seabees?
Q13. The electrode probe type of feedwater control has
what total number of electrode sensors?
Q14. What boiler fitting is considered the most
Q15. What is the function of the guard valve on a boiler?