Minor (Local) Head Loss Calculator (h = K·v²/2g)

Minor (Local) Head Loss Calculator (h = K·v²/2g) | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Math & Numbers
Input types: select, number
Output type: json
Sample coverage: 4
API ready: Yes

Overview

The Minor (Local) Head Loss Calculator estimates head loss and pressure drop caused by pipe fittings, valves, bends, entrances, exits, sudden contractions, and sudden expansions. Enter a loss coefficient K or choose a preset, then provide flow velocity, fluid density, gravity, and the number of identical fittings in series.

When to use

Estimate local head loss from elbows, valves, tees, and other pipe components.
Calculate the pressure drop caused by one or more identical fittings in series.
Compare fitting options using a preset K value or a custom loss coefficient.

How it works

1Choose a component preset or select Custom K and enter the dimensionless loss coefficient.
2Enter mean pipe velocity, fluid density, gravitational acceleration, and fitting quantity.
3The calculator applies hₘ = n·K·v²/(2g) for head loss and ΔPₘ = n·K·ρ·v²/2 for pressure drop.
4Review head loss in meters and feet, plus pressure drop in pascals, kilopascals, and bar.

Use cases

Pipe system design checks for valves, elbows, tees, and other fittings.
Pump and piping calculations that require local pressure-drop estimates.
Hydraulics coursework and fluid-mechanics examples involving velocity head and K factors.

Examples

1. Estimate loss from four standard elbows

Piping engineer

Background

A piping layout contains four 90° standard elbows. The mean flow velocity is 2 m/s, and the fluid density is 1000 kg/m³.

Problem

Calculate the combined local head loss and pressure drop from the elbows.

How to use

Select 90° standard elbow, enter K = 0.9, velocity = 2 m/s, density = 1000 kg/m³, gravity = 9.81 m/s², and quantity = 4.

componentType: elbow_90_std; K: 0.9; velocity: 2; density: 1000; densityUnit: kg_m3; gravity: 9.81; quantity: 4

Outcome

The calculator returns a head loss of 0.7339 m, or 2.408 ft, and a pressure drop of 7200 Pa, or 7.2 kPa.

2. Evaluate a fully open globe valve

Mechanical engineer

Background

A water line uses one fully open globe valve with a flow velocity of 1.5 m/s and water density of 1000 kg/m³.

Problem

Determine the valve's local head loss and pressure drop.

How to use

Choose Globe valve (fully open), leave the preset K value in use, enter velocity = 1.5 m/s, density = 1000 kg/m³, gravity = 9.81 m/s², and quantity = 1.

FAQ

What does the loss coefficient K represent?

K is a dimensionless coefficient describing the local resistance of a fitting, valve, bend, or flow transition.

Can I use a preset K value?

Yes. Select a supported component type to use its typical K value. The K field remains editable.

Can I enter my own K value?

Yes. Select Custom K and provide a nonnegative loss coefficient.

How does quantity affect the result?

For n identical fittings in series, the calculator multiplies the single-fitting loss by n.

Which density units are supported?

Density can be entered in kg/m³, g/cm³, or lb/ft³. Results include metric head-loss and pressure-drop units.

componentType: globe_valve_full; velocity: 1.5; density: 1000; densityUnit: kg_m3; gravity: 9.81; quantity: 1

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Estimate loss from four standard elbows

2. Evaluate a fully open globe valve

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3. Calculate loss with a custom coefficient