Exam Question

Petroleum vapours are dangerous substances and when mixed with air can be ignited.

(a) (i) Sketch an explosimeter or combustion gas indicator which can be used to check the atmosphere of a tank or pump room. (8)

(ii) Describe the explosimeter and its operation (3)

(iii) State one reason that may cause the explosimeter to give a false reading (3)

(b) For flammable mixtures, explain the meaning of the terms lower and upper flammable limits (6)