FARM MOTORS 



bonates and sulphates of lime. These vary with the loca- 

 tion and can be dealt with properly only after experiment. 

 Generally, however, they are thrown down in the boiler 

 in the form of a soft mud and can then be disposed of 

 by blowing out and washing the boiler with a strong 

 stream from a hose. The presence of other impurities, 

 such as oils or organic matter, or even sulphates of lime, 

 makes these lime scales hard and adhesive. Removing 

 the water from the boiler while still hot will cause these 

 scales to bake or dry on the parts, in which case it is 

 very difficult to remove them. Wherever it is possible, 

 run some soft water through the boiler for a few hours 

 before cooling down to clean. The acids will act upon 

 the limes and loosen them from the tubes, etc. 



Since the lime impurities of water are thrown down at 

 a temperature of about 200 F., there are devices on the 

 market which allow the feed water to mingle with the 

 exhaust steam. This heats the former to a temperature 

 sufficient to throw out the lime parts. 



497. Boiler cleaning. It is essential that a boiler be 

 kept clean both inside and out. Authorities have stated 

 that one-tenth inch of scale will require 15 per cent more 

 fuel. Boiler scale is a non-conductor of heat; conse- 

 quently, the flues must be kept hotter to affect the water 

 as much with scale as without. 



The frequency of washing a boiler can only be deter- 

 mined by experience with the water used and the sur- 

 rounding conditions. Usually a traction boiler should 

 be cleaned once a week, but there are wide variations 

 from this rule. 



Often when there is considerable mud in the water it 

 can be blown out by means of the lower blow-off valve. 

 It is good practice to fill the boiler extra full at night; 

 then in the morning when the sediment has settled and 



