Calculating Pressure Drop

Please use a decimal point and not a comma to indicate the decimal place!

The green rows indicated contain results.

The calculation is valid for smooth pipes.

  • SI - unit
  • US - unit
  • Flow rate
    V
    m³/min
    Nominal pipe length
    L
    m
    Nominal pipe inside diameter
    Id
    mm
    Working pressure absolute
    p
    bar
    Pressure drop
    Δp
    bar

The nominal length of the pipework is calculated by adding the straight pipe runs and the equivalent length of each joint or fitting.

The equivalent lengths of the joints and fittings can be calculated from the list or simply estimated as 60% of the straight runs, i.e. total length = total straight runs x 1.6.




Calculation Equivalent pipe length
  • SI - unit
  • US - unit
  • Pipe diameter
    DN
    equivalent length[m]
    Number
    Elbow
    1.5
    Elbow R=2d
    0.3
    Elbow R=d
    0.4
    T-piece through
    0.5
    T-piece branch
    1.5
    Seated valve
    5
    Butterfly / ball valve
    0.3
    Check valve
    2
    Reduction piece (DN): 20
    0.5
    Equivalent lengths of joints and fittings:
    m
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