Question

Given that: Specific gravity of mercury = 13.6; intensity of pressure = 40 kPa

Express the intensity of pressure (gauge) in various units (S.I)
1. 0.3 bar, 3.077 m of water, 0.15 m of mercury
2. 0.4 bar, 4.077 m of water, 0.299 m of mercury
3. 0.5 bar, 5.077 m of water, 0.339 m of mercury
4. None of the above

Answer 1

Correct Answer - Option 2 : 0.4 bar, 4.077 m of water, 0.299 m of mercury

Concept:

Pressure = 40 kPa

1 bar = 10⁵ Pa ⇒ 100 kPa

⇒ 40 kPa = 0.4bar

In terms of water head:

P = ρgh

For water, ρ = 1000 kg/m³, g = 9.81, P = 40 kPa

\( \Rightarrow h = \frac{{40 × {{10}^3}}}{{1000 × 9.8}} = 4.08\;m\;\)of water 

In terms of Mercury head:

For Mercury, ρ = 13.6 × 10³ kg/m³, P = 40 kPa

\( \Rightarrow h = \frac{{40 × {{10}^3}}}{{13.6 × 1000 × 9.8}} = 0.30~m\;of\;mercury\)