A manometer containing an oil with a specific gravity (SG) of 0.92 is connected across an orifice plate in a horizontal pipeline carrying seawater (SG = 1.1). If the manometer reading is 16.8 cm, what is the pressure drop across the orifice?

Solution :

Given :

1) S.G of Oil = 0.92

$\rho_{oil}$ = 920 kg/m³

2) S.G of Seawater = 1.1

$\rho_{seawater}$ = 1100 kg/m³

3) Difference in level (h) = 16.8 cm

&= 0.168 m

Required Concept

Below is the diagram to understand the concept required to to understand this problem

Hence the difference in the pressure between inlet and outlet , when both are at same level is given by,

$\Delta P= g × h × (\rho_{seawater}– \rho_{oil})$

Note that, we considered the inlet and outlet where the manometer is connected

$\Delta P= 9.81 × 0.168 × (1100– 920)$

$\Delta P =294.65 N/m²$