150 STEAM BOILERS 



Rapidity in Cleaning Fires. Rapidity in cleaning fires is of 

 great importance, as during the operation a large volume of 

 cold air enters the furnace and chills the metallic surfaces with 

 which it comes in contact; consequently, the boiler is damaged, 

 however slightly. It is the greatest advantage of shaking 

 grates that they allow the fire to be cleaned without opening 

 the furnace door; the inrush of cold air and consequent chilling 

 of the plates, etc. is thus avoided. 



Before starting to clean fires, the steam pressure and the 

 water level should be run up as high as is safe and the feed 

 should be shut off in order to reduce the loss in pressure v/hile 

 cleaning. The condition of the fire during cleaning and the 

 opening of the furnace doors cause the pressure to drop quite 

 rapidly, but the rapidity and the amount of drop will be reduced 

 by taking the precautions mentioned and cleaning quickly. 



Drop of Pressure During Cleaning. The amount of drop 

 in pressure while cleaning fires depends on several conditions. 

 For example, with a boiler that has a small steam space and, 

 in addition, is too small for the work required of it without 

 forcing, it is to be expected that the drop in pressure will be 

 much more than if the reverse conditions exist. Furthermore, 

 it may be necessary to clean fires while steam is being drawn 

 from the boiler, instead of being able to clean at a time when 

 the engine is stopped. In that case a greater drop must be 

 expected than when cleaning while no steam is being drawn 

 from the boiler. It is advisable when possible to do the clean- 

 ing at a time when no steam is being drawn from the boiler or 

 when the demand for steam is light. 



FIRING WITH LIQUID FUEL 



Number of Oil Burners Required. The number of oil 

 burners to be installed in a given boiler depends on the type of 

 burner to be used and .the width of the furnace. The object 

 to be attained is a uniform distribution of heat throughout the 

 furnace. A straight-shot burner will produce a long, compact 

 flame, whereas a fan-tailed burner will produce a wide, short 

 flame; hence, one burner of the latter class may be sufficient for 

 a furnace that would require two burners of the former class. 

 One fan-tailed burner will ordinarily be sufficient for a furnace 



