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 following:
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 the operator.
When starting the injector. first open the water supply valve (fig. 1-13B) about one full turn. Nest 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 water.
The water supply should not be hotter than 120F 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.
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.
Q9. Blowdown valves are installed at what location in a boiler?
Q10. How often should the fusible plugs in a boiler be renewed?
Q11. 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 important?
Q15. What is the function of the guard valve on a boiler?
Learning Objective: Identify the automatic controls commonly used on boilers and describe the function of each.
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 control valve.Continue Reading