Chapter 11-BOILER FITTINGS AND CONTROLS 



SUPERHEATER 



GENERATING BANK 



BOTTOM BLOW VALVE 



OVERBOARD 



DISCHARGE 



VALVE- 



r— GUARDING 

 \ VALVE 



SURFACE 

 BLOW VALVE 



-SIDE 

 WALL 

 TUBES 



SIDE 



WALL 



HEADER 



FROM OTHER BOILER 



SKIN OF SHIP 



38.58 



Figure 11-25.— Boiler blow piping for single-furnace boiler. 



the studs after the gage has warmed up. (Notice 

 the numbering of studs in figure 11-28; the 

 numbers indicate theproper sequence of tighten- 

 ing the studs when assembling the gage.) 



On some boilers of recent design, a bi- 

 color water gage is used. Bi-color gages show 

 RED in the portion of the glass which is filled 

 with steam and GREEN in the portion of the 

 glass which is filled with WATER. The bi-color 



gage glass works on the simple optical prin- 

 ciple that a ray of light bends (or refracts) a 

 different amount when it passes through steam 

 than when it passes through water. 



Each water gage is connected to the steam 

 drum through two cutout valves, one at the top 

 and one at the bottom. The bottom cutout valve 

 connection contains a ball-check valve. The 

 ball rests on a holder. As long as there is 



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