Question

What does ‘a’ in psia mean?

(a) Pressure is measured below absolute pressure

(b) Pressure is measured above absolute pressure

(c) Pressure is measured below absolute zero

(d) Pressure is measured above absolute zero

I got this question by my college director while I was bunking the class.

Origin of the question is Effect of Acceleration in  Suction and Delivery Pipes on Indicator Diagrams topic in division Indicator Diagrams of Fluid Mechanics

Answer 1

Right choice is (d) Pressure is measured above absolute zero

Explanation: All the units in NPSH are psi units. The psi units are kilopascal, bar, pounds per square inch etc. The ‘a’ in psia indicates that the pressure is measured above absolute zero which is a perfect vacuum.