THE BOILER 



The stop-cocks that are placed in some steam-gage 

 siphons should always be left open. 



The Pop Safety Valve. The safety valve opens when 

 the pressure reaches a certain point, allowing the excess 

 steam to escape and closes 

 when the pressure has been 

 reduced a few pounds. The 

 valves are usually set at 

 the factory to blow off at 

 one hundred and thirty 

 pounds. If a change of 

 pressure be desired, un- 

 screw the jam nut at the 

 top and apply the key, pro- 

 vided for this purpose, to 

 the pressure screw. For 

 more pressure, screw 

 down; for less, unscrew. 

 After having obtained the 

 desired pressure, screw 

 the jam nut down tight on 

 the pressure screw. To 

 regulate the opening and closing action of the valve, take 

 the pointed end of a file and apply it to the teeth of the 

 regulator. If the valve closes with too much loss of 

 boiler pressure, move the regulator to the right. This can 

 be done when the valve is at the point of blowing off. 



FIG. 35- SECTIONAL VIEW 

 OF POP VALVE. 



