Question

The differential pressure transmitter of a flow meter using orifice reads $50{\text{kg/m}}^2$ for a particular flow rate. If the flow rate is quartered (within the range of orifice), the corresponding reading of differential pressure transmitter across orifice in ${\text{kg/m}}^2$ is _________?

• A. 3.125

Answer 1

The correct option is A 3.125
The flow rate is directly proportional to the square root of difference pressure.

$Q\propto \sqrt{\Delta P}$

$\therefore \frac{Q_1}{Q_2}=\sqrt{\frac{\Delta P_1}{\Delta P_2}}$

$\text{Now given}{Q}_2=\frac{1}{4}{Q}_1$

$\therefore \frac{Q_1}{\frac{1}{4}{Q}_1}=\sqrt{\frac{50}{\Delta P_2}}$

$\Rightarrow 4=\sqrt{\frac{50}{\Delta P_2}}$

$\Rightarrow 16=\frac{50}{\Delta P_2}$

$\Delta P_2=\frac{50}{16}=3.125{\text{kg/m}}^2$