Question

If petrol has a density of 800 kg/m^3 and the discharge nozzle is located 8 mm above the level of petrol in a float chamber. What is the pressure differential causing airflow?

(a) 62.78 Pa

(b) 42.78 Pa

(c) 52.78 Pa

(d) 72.78 Pa

This question was addressed to me during an interview.

Query is from Petrol Engine Fuel System topic in chapter Fuel Supply System of Automobile Engineering

Answer 1

The correct option is (a) 62.78 Pa

To explain: When the fuel flow just starts ΔPf = 0 i.e. ΔPa – ghρf = 0. (ΔPf = pressure differential causing fuel flow, ΔPa = pressure differential causing airflow, h = height of nozzle above the fuel level, ρf = density of fuel) ΔPa – 9.81*(8*10^-3)*800 = 0 i.e. ΔPa = 62.78 Pa.