U-Tube Differential Pressure Manometers

Pressure measuring devices using liquid columns in vertical or inclined tubes. Calculate differential pressure using vertical or inclined U-tube manometers with adjustable specific weight, column height, and angle parameters.

Calculator

Inputs

Results

Vertical Pressure Difference-- Pa
Inclined Pressure Difference-- Pa
FluidSpecific Weight (kN/m³)Specific Weight (lb/ft³)Common Applications
Water9.862.4Most common, air flow measurement
Mercury133.1849High pressure differential measurement
Oil8.554Low pressure sensitive applications
Alcohol7.849.7Low temperature applications

Theory

Vertical U-Tube Manometer

Pressure difference is calculated as:

pd = γ × h = ρ × g × h

Where:

  • pd = pressure difference (Pa)
  • γ = specific weight of liquid (kN/m³)
  • h = liquid column height (m)
  • ρ = liquid density (kg/m³)
  • g = acceleration of gravity (9.81 m/s²)

Inclined U-Tube Manometer

For improved accuracy at low pressures:

pd = γ × h × sin(θ)

Where:

  • θ = angle of column relative to horizontal plane (degrees)
  • Inclining the tube increases measurement accuracy by increasing the effective column length

Example

For a water manometer with 10 mm column height at 45° inclination: pd = (9.8 kN/m³) × (10 mm) × sin(45°) = 69.3 Pa