DEVELOPMENT OF HOUSE HEATING 



139 



by the point, B. Similarly, the boiling point is 180C., or 

 356F., when the pressure is 145.93 Ib. This is shown by the 

 point, C. You should study this curve till you understand it 

 thoroughly. 



2<X>'c-392'r\ 

 I80C-356F 



Q) 





/20C-248F\ 



SOC-l40r 



t>G 



A 



Pounds Pressure 



FIG. 102. The temperature-pressure curve. 



161. The Temperature of Steam in a Boiler. The common 

 steam boiler for residence heating usually carries from 3 to 8 

 Ib. of steam as indicated by the pressure gauge. Supposing 

 that the gauge on a boiler registers 6.1 Ib. By using Table VI, 

 Art. 155, or the curve, Fig. 102, we can tell the temperature 

 of the steam in the radiators. Show that the absolute pres- 

 sure is 20.8 Ib. and that the temperature of the steam is 110C., 

 or 230F. 



In such a steam heating plant as is shown in Fig. 97, the 

 boiler often carries 60 or even 80 Ib. of pressure as indicated 

 by the pressure gauge. If the gauge indicates 60 Ib., show that 



