Question

Blow back is:

a) number of minutes the valve operated before closing
b) volume of steam discharged
c) difference between the popping and closing points of the safety valve
d) pressure when valve closes

Answer 1

c) difference between the popping and closing points of the safety valve. Blow back is the difference between the popping and closing points of the safety valve.

Step-by-step explanation:

The term 'blow back' refers to the difference between the popping and closing points of the safety valve. When the pressure in a system exceeds the set limit, the safety valve pops open to release the excess pressure. Once the pressure decreases to a certain point, the valve closes again. The blow back is the difference between these two points, indicating the amount of pressure that is released before the valve closes.