Question

The pressure drop across an orifice plate for a particular flow rate is 5 kg/m². If the flow rate is doubled (within the operating range of the orifice), the corresponding pressure drop in kg/m² is
1. 2.5
2. 5.0
3. 20.0
4. 25.0

Answer 1

Correct Answer - Option 3 : 20.0

Given that,

Pressure drop (ΔP₁) = 5 kg/m²

Flow rate (Q) is doubled.

= Q₂ = 2Q₁

The relation between pressure drop and flow rate is,

\(Q \propto \sqrt {{\rm{\Delta }}P}\)

\(\Rightarrow \frac{{{Q_1}}}{{{Q_2}}} = \;\sqrt {\frac{{{\rm{\Delta }}{{\rm{P}}_1}}}{{{\rm{\Delta }}{{\rm{P}}_2}}}}\)

\(\Rightarrow \frac{{{Q_1}}}{{2{Q_1}}} = \;\sqrt {\frac{5}{{{\rm{\Delta }}{{\rm{P}}_2}}}}\)

⇒ ΔP₂ = 5 × 4 = 20 kg/m²