Chapter 11-BOILER FITTINGS AND CONTROLS 



DIAPHRAGM 



PRESSURE FROM 

 SUPERHEATER INLET 



PIN LINKAGE 



CALIBRATION 



ADJUSTING 



SCREW 



ARMATURE 

 WELL 



SEALING PLUGS 



Figure 11-31.— Cross section of Yarway indicating unit 

 (plan view). 



98.92 



The oil drip detector periscope operates on much 

 the same principle as the smoke periscope. 



Pressure and Temperature Gages 



Boiler operation requires constant aware- 

 ness of the pressures and temperatures existing 

 at certain locations within the boiler and in 

 associated machinery and systems. Operating 

 personnel depend upon a variety of pressure 

 and temperature gages to provide them with the 

 necessary information. Pressure gages are in- 

 stalled on or near each boiler to indicate steam 

 drum pressure, superheater outlet pressure, 

 auxiliary steam pressure, auxiliary exhaust 

 pressure, feed water pressure, steam pressure 

 to the forced draft blowers, air pressure in the 

 double castings, and fuel oil pressure. Tempera- 

 ture gages are installed to indicate superheated 

 steam temperature, desuperheated steam tem- 

 perature (if the boiler has a desuperheater), 

 feed water temperature at the economizer inlet 

 and outlet, fuel oil temperature at the fuel oil 

 manifold before the boiler, and— in some ships- 

 uptake temperature. 



In some firerooms, the gages that indicate 

 steam drum pressure, superheater outlet 

 pressure, superheater outlet temperature, and 



combustion air pressure are installed on the 

 boiler front. As a rule, however, the indicating 

 units of all pressure gages are mounted on a 

 boiler gage board which is easily visible from 

 the firing aisle. Distant-reading thermometers 

 are also installed with the indicating unit mounted 

 on the boiler gage board. In some installations, 

 a common gage board is used for all the boilers 

 in one space, instead of having separate gage 

 boards for each boiler. 



Most of the pressure gages used in con- 

 nection with boilers are of the Bourdon-tube 

 type, although some diaphragm-type gages and 

 some manometers are also used in the fire- 

 room. The temperature gauges most commonly 

 used in the fireroom are direct- reading liquid- 

 in-glass thermometers and distant-reading 

 Bourdon-tube thermometers. The basic operat- 

 ing principles of these pressure and temperature 

 gages are discussed in chapter 7 of this text, 



Single-Element Feed Water Regulators 



Single-element automatic feed water regu- 

 lators are installed on many boilers which are 

 not equipped with complete automatic feed water 

 and combustion control systems. Single-element 

 regulators, unlike the multi-element control 



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