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U TUBE MANOMETER CALCULATOR

U-tube manometer diagram

U-tube manometers are used to measure the gauge pressure at point A relative to the atmosphere. The chamber fluid with density ρ1 is separated from the atmosphere by a second fluid with density ρ2. The gauge pressure at A can be written as:

pA(gage) = ρ2 g h2 − ρ1 g h1
or   pA(gage) = γ2 h2 − γ1 h1

pA(abs) = ρ2 g h2 − ρ1 g h1 + patm
or   pA(abs) = γ2 h2 − γ1 h1 + patm

If the chamber at A contains only gas, the term γ1 h1 is usually negligible and the equations simplify to:

pA(gage) ≈ ρ2 g h2   (or γ2 h2)
pA(abs) ≈ ρ2 g h2 + patm   (or γ2 h2 + patm)

KNOWN PARAMETERS
INPUT PARAMETERS
Density ρ₁
Density ρ₂
Specific Weight γ₁
Specific Weight γ₂
Gravity g
Depth h₁
Depth h₂
Atmospheric Pressure patm

Note: If fluid 2 is below point 3, then enter negative height values for h₂.

Note: Use dot “.” as decimal separator.

RESULTS
Pressure A Gauge pA(gage) -- bar
Pressure A Absolute pA(abs) -- bar

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Reference