Question

A large amount of a mixture of ethylene, 1-butene, and n-pentane at 435 psia and 210°F ecaped to the atmosphere and was ignited.

FLAMMABLE LIMITS IN AIR (VOL %)
COMPONENT	LOWER	UPPER
Ethylene	3.1	32
1-Butene	1.6	9.3
n-Pentane	1.4	8.0

The concentration (vol%) of this hydrocarbon vapor in the air at the point of ignition was most nearly:

a. 50                                                         c. 5

b. 99                                                         d. 1

Answer 1

the ignition occure only when flammable matrial is with in upper and lower flammability limit means for all component between ( max 32 and min 1.4)

a) 50 this is out side the range hence not ignite more material present and oxygen deficiency

b) 99 it is also outside the range , oxygen deficiency so not ignite

c) it is with in the limit so so there is strong chance of ignition

d) 1 it is also out side the range so less material is available for ignition hence not ignite