This calculator determines the pressure drop of a compressible gas or vapour through a pipeline. The calculator can model isothermal and adiabatic flow.

Compressible Line Sizing Calculator Guide

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**Show Instructions**

The calculator determines the frictional pressure drop through a line assuming either isothermal or adiabatic compressible flow.

The assumption of compressible flow is reasonable for gases and vapours where the calculated pressure drop is greater than 10% of the upstream pressure.

- Enter the line number, source and destination of the line
- Select the flow type - isothermal or adiabatic:
- Isothermal flow is usually assumed for long pipes
- Adiabatic flow is usually assumed for short, insulated pipes
- Enter the fluid details and physical properties
- Choose the nominal diameter and schedule of the pipe from the drop down lists
- The calculator will determine the inside diameter of the selected pipe
- Enter a length for the pipe
- Enter an absolute roughness for the pipe. Typical values:
- Commercial steel: 0.046 mm
- Drawn tubing (brass, lead, glass): 0.002 mm
- Asphalted cast iron: 0.122 mm
- Galvanized iron: 0.152 mm
- Cast iron: 0.259 mm
- Enter the quantities of each type of fitting for the pipe if known
- If the type and quantities of each fitting are unknown, enter a fitting factor. Typical factors for 50 metre long lines:
- 3" diameter and smaller: 1.5
- 4" and 6" diameter: 2.0
- 8" diameter and larger: 2.5
- Click the "Calculate" button
- The calculator will determine the outlet pressure and the frictional pressure drop through the line
- An error will be given if the specified flow rate is too high to be achieved through the pipe with the available pressure drop. In this case:
- Reduce the flow rate
- Increase the pipe diameter
- Increase the inlet pressure