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Mechanical Engineering2D

Pressure Loss Calculator

Calculate total pressure loss in a pipeline including friction losses and fittings (K-factor method).

Inputs
Enter your values below

Sum K for all fittings: elbow≈0.9, globe valve≈6

Result
Total Pressure Loss
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Enter values and click Calculate
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Formula
(friction × length ÷ diameter + k_total) × density × velocity² ÷ 2 ÷ 1000
Result unit: kPa

ΔP = (fL/D + ΣK) × ρv²/2. K-factor method sums minor losses from fittings: elbow≈0.9, gate valve≈0.17, globe valve≈6, tee≈1.8.

Introduction

Calculate total pressure loss including both straight-pipe friction and minor losses from fittings, valves, elbows, and entrances/exits using the K-factor (resistance coefficient) method.

How This Calculator Works

ΔP = (fL/D + ΣK) × ρv²/2. K-factor method sums minor losses from fittings: elbow≈0.9, gate valve≈0.17, globe valve≈6, tee≈1.8.

Step-by-step process:

  1. Enter your input values in the calculator above
  2. The engine converts all inputs to SI base units (meters, kg, Pa)
  3. The formula is evaluated: (friction * length / diameter + k_total) * density * velocity^2 / 2 / 1000
  4. Result is formatted with the appropriate unit and precision

Calculation Example

50m pipe with K=5 fittings, water at 2m/s: 30 kPa total loss.

Inputs: friction=0.02, length=50, diameter=100, k_total=5, density=1000, velocity=2
Result: 30 kPa

Engineering Applications

  • •Pump head estimation
  • •Piping system design
  • •Fire protection systems
  • •HVAC hydronic design

Frequently Asked Questions

What are typical K-factors?

90° elbow: 0.9, 45° elbow: 0.4, gate valve (full open): 0.17, globe valve (full open): 6, ball valve: 0.05, tee (through flow): 0.9, tee (branch): 1.8.

What is the difference between K-factor and L/D?

Equivalent length (L/D) methods convert fittings to equivalent pipe length. K-factor method uses velocity head directly: h_loss = K × v²/2g. Both give same result.

How do I convert pressure loss between bar, psi, and kPa?

1 bar = 100 kPa = 14.5038 psi = 10.197 m of water column. 1 psi = 6.8948 kPa = 0.06895 bar. Use these factors to convert results when comparing with pump curves or valve datasheets.

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Engineering Disclaimer: Calculations are for reference and educational purposes only. Always verify results independently for engineering design. See full disclaimer.
Reviewed by: Industrial Engineering Team
References: ASME B31.3, ASTM A36, Perry's Chemical Engineers' Handbook