512 



Farm Mechanics. 



to escape, thus relieving the pressure and at the same time 

 warning the engineer by the sound of the escaping steam. 

 The position of -the safety 

 valve is represented at 5, Fig. 

 244. 



Care should be taken by 

 the operator to see that this 

 valve 'is in good working or- 

 der 'by raising it gently at 

 times to see that it has not be- 

 come set in some way. The 

 weight which has been pro- 

 vided by the manufacturers 

 to hold the valve against the 

 steam pressure should never 

 be made heavier by loading 

 or so set that it will oppose a 

 greater pressure than the 

 maximum intended for the 

 boiler. 



In Fig. 247 is represented 

 the Kunkle lockup pop safety valve operated by a spring 

 instead of a lever and weight. 



641. Care of the Boiler. In order to get the best results 

 from a boiler it is necessary that the flues be often cleaned 

 in order that there may be no soot or ashes to prevent the 

 heat coming in direct contact with the metal. How often 

 this should be done must depend entirely upon circum- 

 stances. Oftentimes it should be done daily, at any rate 

 the flues should be kept clean and the draft perfect. 



Periodically it is necessary to clean the interior of the 

 boiler to remove the scale and sediment which accumulates 

 from the water used in making the steam, (649). Ho\r 

 often this must be done will depend entirely upon the 

 character of the water. In some cases it must be done 

 once a week but with clean soft water it may not be 

 required oftener than once in six months. 



FIG. 247. Kunkle lockup pop safety 

 valve. 



