WHY HOT WATER PIPES Bl'RST 237 



WHY HOT WATER PIPES IN HOUSEHOLD PLUMBING 



BURST MORE FREQUENTLY THAN COLD 



WATER PIPES. 



F. C. BROWN AND WALDEMAR NOLL. 



Plumbers often notice that the hot water pipes in a plumbing 

 system that lead to the bathroom or kitchen bursl more fre- 

 quently than the pipes carrying cold water. It is said that the 

 ratio is at least four to one. The "Cold Water" usually freezes 

 so as to lessen the flow of water in the pipes, or to stop the flow 

 altogether, but the freezing seidoni bursts the pipes unless the 

 temperature is very low. 



In verifying the plumber's observations the exact conditions 

 as they exist in the pipes w r ere not obtained, but some of the 

 essential features were approached by substituting ulass test 

 tubes for the pipes. The freezing conditions were simulated 

 by filling one set of tubes with tap water, freshly drawn, and 

 by filling an alternate set of tubes with tap water which had 

 been boiled and then cooled to the temperature of the water in 

 the other tubes. The glass tubes were of especial advantage in 

 that the visible appearance inside the tubes gave valuable in- 

 formation on what was occurring in the respective cases. 



The tests carried out fully substantiated the phenomenon that 

 hot water pipes burst more frequently than cold water pipes. 

 On seven different occasions over fifty pairs of tubes were used, 

 filled alternately with boiled and unboiled water, brought to the 

 same temperature. They were placed in the open air when the 

 temperature was below the freezing point. The limes of freezing 

 varied from a half hour, or even less, to three or four hours. 

 The tubes were of varying size 1ml most <A' them were one centi- 

 meter in diameter. 



Of fifty pairs of tubes used twenty-two pairs burst, and in 

 eighteen pairs the boiled broke before the unboiled, and in four 

 pairs the unboiled broke first. 



The observations of the plumbers bein li verified, the next step 

 was to find an explanation of the phenomenon. One day, when 



