Manometer (Same Fluid)

p_{1} - p_{2} = γ h

The pressure difference between two points in a continuous static fluid equals specific weight times the vertical elevation difference. Tube diameter drops out (ideal). For mixed fluids, sum γh along each leg from 1 to 2.

$p_{1}, p_{2}$ (Pa): Pressures at the two points
$γ$ (N/m³): Specific weight of the manometer fluid
$h$ (m): Vertical difference in fluid columns

Step-by-step solved example

A water manometer reads h = 250 mm. Pressure difference?

U-tube: p1 − p2 = γh for the connecting fluid column.

1. Convert h
h = 0.250 m. γ_water = 9810 N/m³.
2. Δp
p1 − p2 = 9810 × 0.250 = 2450 Pa = 2.45 kPa.
$Δ p = 2.45 kPa$

Answer: 2.45 kPa

10 practice questions

0/10 correct

1.300 mm of water. Δp =

2.100 mm of mercury (SG = 13.6). Δp ≈

3.An ideal manometer reading is independent of

4.For the same fluid, p1 − p2 equals

5.0.50 m of oil, SG = 0.80. Δp =

6.The open end of a manometer feels

7.To increase sensitivity (larger h for the same Δp) use

8.A differential manometer measures

9.20 kPa is equivalent to how much water column?

10.A U-tube with two fluids requires