Pipe Sizing & Pressure Drop

mechanical

Selects pipe size and calculates pressure drop for a given fluid, flow rate, and pipe material. Supports Darcy-Weisbach and Hazen-Williams methods. Pulls real fluid properties, pipe dimensions, friction factors, and fitting loss coefficients from reference tables.

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Fluid*

Fluid name matching the fluid-properties reference table (e.g. 'water', 'air', 'ethylene_glycol_50'). Used to look up density and dynamic viscosity at the specified temperature.

Temperature C

Fluid temperature for property lookup. Affects density and viscosity, which drive Reynolds number and friction losses. Typical: 4-90 C for water systems, -40 to 200 C for process fluids. If omitted, defaults to 20 C.

Flow Rate M3 S*

Volumetric flow rate through the pipe. Typical: 0.001-0.1 m3/s for building systems, 0.1-1.0 m3/s for mains and process headers.

Pipe Material

Pipe material and condition, used for Hazen-Williams C lookup and roughness estimation. Examples: 'carbon_steel_new', 'stainless_steel', 'PVC', 'cast_iron', 'ductile_iron', 'copper', 'HDPE', 'galvanized_steel'. If omitted, defaults to carbon_steel_new.

Pipe Schedule

ASME pipe schedule for wall thickness and ID lookup. Common schedules: '5', '10', '40', '80', '160', 'STD', 'XS', 'XXS'. Schedule 40 is standard for most building and process piping. If omitted, defaults to Schedule 40.

Pipe Length M

Total equivalent straight length of the pipe run in meters. Used to compute major (friction) head losses. Does not include minor losses from fittings (those are added separately). Total straight-run length. Typical: 10-100 m for building, 100-5000 m for distribution. If omitted, defaults to 100 m.

Fittings

List of fitting types to include for minor loss calculation. Each fitting's K factor is looked up from the pipe-fittings reference table. Examples: 'elbow_90_std', 'tee_branch', 'gate_valve', 'check_valve_swing'. If omitted, no minor losses are included.

Method

Friction loss method. Darcy-Weisbach is general-purpose and valid for any fluid and flow regime. Hazen-Williams is empirical, limited to water near 60 F in turbulent flow, but widely used in fire protection and water distribution. If omitted, defaults to darcy-weisbach.

Max Velocity M S

Maximum allowable fluid velocity for pipe size selection. Typical: 1.5-3.0 m/s for water in buildings (ASHRAE), up to 6 m/s for fire mains, 15-25 m/s for steam, 0.5-1.5 m/s for suction lines. If omitted, defaults to 3.0 m/s.

Roughness Mm

Absolute pipe roughness override in millimeters. If omitted, roughness is estimated from pipe_material. Typical: 0.045 mm for new carbon steel, 0.0015 mm for copper/PVC, 0.26 mm for cast iron, 1.0 mm for concrete.

Reference data

This calculator pulls live values from the following engineering reference tables in the database.

pipe sizes
fluid properties
hazen williams c
pipe fittings

About this calculator

Pipe Sizing & Pressure Drop is part of the Engineering Database calculator suite. Each tool runs deterministic calculations against authoritative reference data and code-compliant methods, so results are reproducible and traceable to source standards.

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Reference data

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