1915] 



on Gaseous Explosions 



275 



the increasing rate but actual contact with the walls ; so it was con- 

 sidered that when the rate of rise of pressure became less towards 

 maximum pressure, this was due to the fact that the vessel at this 

 point was entirely filled with flame. The first part of the rising line 



5 6 



TIME SECS, 



Fig. 5. — Explosion and Paet Cooling Curves of Various Mix- 

 tures OF Gas and Air at initial pressure of 34*5 lbs. per 

 sq. in. absolute. (Bairstow and Alexander). 



Explosion in a Closed Vessel. (Bairstow and Alexander). 



Initial pressure 34*5 lbs. per sq. in. 



Initial temperature ...... 17° C. 



Mixture containing from 7-79 per cent to 14*98 per cent gas. 



Fraction of 



total volume 



occupied by gas, 



per cent 



Maximum pressure 



observed, 



lbs. per sq. in. above 



atmos. 



Time to reach 



maximum pressure, 



in seconds 



7-79 

 9-23 

 10-72 

 12-05 

 13-5 

 14-98 



97 

 193 

 210 

 245 

 263 

 272 



0-8 



0-24 



0-13 



0-07 



0-05 



0-04 



Maximum 

 temperature of 

 explosion, °C. 



540 

 1350 

 1540 

 1790 

 1930 

 2010 



occurred while the vessel contained part flame, part gas mixture as yet 

 untouched by the flame. The flame spread relatively slowly at first, 

 but as it spread it compressed the unburned gases into a smaller space 

 before it and raised the temperature by compression. This raised 

 the rate of flame travel and also diminished the distance through 

 which the flame had to travel. As a consequence, after the start of the 



