Pipe Sizing and Pressure Drop — online
Pressure drop or allowable flow for liquid, gas and steam lines, with fittings, elevation, choked-flow and flashing checks and a size table over every NPS of your schedule.
Yellow cells are inputs; orange cells are choices; blue cells choose the unit. Select or hover over an input to see its help in the box below the toolbar. The sheet is the same as the Excel tool (USD 29) — the Guide, method and references are in the Excel file.
What this pipe sizing and pressure drop calculator does
Size a line, or check one that is already running, for liquids, gases or steam. The tool also tells you when a gas line will choke or a liquid will flash. Pressure drop or allowable flow for liquid, gas and steam lines, with fittings, elevation, choked-flow and flashing checks and a size table over every NPS of your schedule.
- Any fluid. Water and steam, gases and gas mixtures, hydrocarbons, solvents, glycols and brines, oils and petroleum fractions from the built-in fluid library, or your own density and viscosity.
- Pipe and friction. NPS ½ to 36 inch in schedules 5S to XXS or your measured bore; Darcy–Weisbach with the Colebrook equation, laminar flow and the transition region.
- 27 fittings and valves. Elbows, tees, valves, entrances and exits with their K values, plus strainers or equipment as extra losses.
- Gas and steam lines. Average density for small drops, isothermal flow for long lines and adiabatic flow with friction for plant lines, with the choking check and Mach number.
- Size table. The same flow in every size of your schedule, with the smallest size that meets the velocity and pressure-drop guides for 15 services.
- Flow for an allowed drop. The flow a line can pass for the pressure drop you have, and a one-page report for the calculation file.
What you enter
- Calculate
- Gas flow method
- Fluid
- Phase
- Properties
- Temperature
- Inlet pressure
- Solution strength (glycol, brine …)
- Watson characterisation factor K
- Kinematic viscosity at 40 °C (oil)
- Kinematic viscosity at 100 °C (oil)
- Density (your value)
- Viscosity (your value)
- Molar mass (gas, your value)
What you get
- Actual volume flow at the inlet
- Density at the inlet
- Viscosity
- Velocity at the inlet
- Reynolds number
- Darcy friction factor
- Friction pressure drop per 100 m of pipe
- Straight pipe
- Fittings, valves and other losses
- Elevation
- Total pressure drop
- Outlet pressure
- Velocity at the outlet
- Mach number, inlet / outlet
How it was checked
Perry's Example 6 (fittings and valves) gives the same tank level, 0.74 m against 0.73 m; Perry's Example 8 (choked air flow) gives 2.73 kg/s against 2.7 kg/s; 17 of 17 checks against an independent model within tolerance.
Related
- Free quick calculator — a simpler free version for a fast estimate.
- Calculation guide — the equations behind this tool, with a worked example.
- Pipe Sizing and Pressure Drop Excel tool — USD 29, keep the workbook and its Guide.
- All 40 online tools
Questions
Is the pipe sizing and pressure drop calculator free?
You can enter and check all your data free. The full results, findings and printable sheet are unlocked with a 3-run pack (USD 9), a monthly subscription to all 40 online tools (USD 15) or a yearly one (USD 99).
Are the results the same as the Excel tool?
Yes. The online tool runs the formulas of the Pipe Sizing and Pressure Drop Excel workbook, checked cell by cell against the Excel file.
Which units can I use?
SI, US customary and British units — choose the unit next to each input.