PRINCIPLES OF NAVAL ENGINEERING 



PRESSURE 

 SWITCH 

 STOPS PUMP 

 AT 800 PSIG 



Figure 9-22.— Fuel oil service system for forward plant, DLG 14 and DLG 15. 



147.80 



is installed to permit bypassing the fuel oil 

 heaters in unusual operating situations. Fuel 

 oil heater valves control the flow of oil into 

 the heaters and permit shifting from one heater 

 to another. 



The main fuel oil valve controls the flow 

 of fuel oil in the line leading to each boiler. 

 The emergency quick- closing valve can be 

 operated from both the upper level and the 

 lower level at the boiler front. In some installa- 

 tions, a latched-open solenoid valve, arranged 

 for local tripping, is installed adjacent to each 

 burner supply manifold; where a solenoid valve 

 of this type is installed, it takes the place of 

 the emergency quick- closing valve. 



A micrometer valve is installed at the top 

 of each burner manifold. The micrometer valve 

 is used for the manual control of fuel oil pres- 

 sure; thus it is the valve that controls the amount 



of oil being burned in the boiler furnace. From 

 the burner manifold, a small flexible line goes 

 to each burner. A small valve called a burner 

 root valve is installed in each burner line to 

 permit shutting off the supply of oil to any burner 

 that is not in use. And finally, an atomizer 

 valve is installed on each burner at the atomizer 

 connection. This valve allows oil to go through 

 the atomizer and be sprayed out into the boiler 

 furnace in such a way that combustion takes 

 place. 



At the lower end of each burner manifold, 

 a recirculating valve is installed. By means of 

 these valves and the recirculating line, fuel oil 

 can be returned from the burner manifold to 

 the suction side of the fuel oil service pump. 

 The recirculating line is used to circulate oil 

 through the fuel oil heaters and thus bring the 

 oil up to the proper temperature for lighting 



224 



