Step-by-Step Fire Pump Calculation (With Example) | Fire Fighting Design Guide

Fire pump calculation is a critical part of any fire fighting system design. Whether you are designing for a residential G+5 building or a commercial project, selecting the correct pump ensures adequate pressure and flow during emergencies.

This guide explains step-by-step fire pump head calculation with a practical example, based on IS 2189 and NBC 2016.

📐 What is Fire Pump Head?

Fire pump head is the total pressure required to deliver water from the source to the most critical point in the system.

It includes:

• Static Head
• Friction Loss
• Residual Pressure

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🧮 Fire Pump Head Formula

$H = H_s + H_f + H_r$H=Hs​+Hf​+Hr​

Where:

• Hs = Static Head
• Hf = Friction Loss
• Hr = Residual Pressure

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🏢 Step-by-Step Fire Pump Calculation (With Example)

🔹 Step 1: Calculate Static Head

👉 Static head = vertical distance from pump to highest outlet

Example:

• Building height = 18 m (G+5)

✔ Static Head = 18 m

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🔹 Step 2: Calculate Friction Loss

Friction loss depends on:

• Pipe length
• Pipe diameter
• Flow rate

👉 For small residential buildings, assume:

✔ Friction Loss = 5–10 m

Example:
✔ Take = 7 m

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🔹 Step 3: Add Residual Pressure

Residual pressure ensures proper water discharge at hydrant.

✔ As per standards:

• Minimum = 7 kg/cm² (~70 m) for hydrant (but small buildings may use lower practical values depending on design approach)

👉 For G+5 practical design:

✔ Residual Pressure = 15 m

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🔹 Step 4: Total Pump Head

Now calculate:

• Static Head = 18 m
• Friction Loss = 7 m
• Residual Pressure = 15 m

👉 Total:

✔ Total Head = 40 m

Fire Pump Head Calculator

Calculate

📊 Fire Pump Flow Requirement

For G+5 residential building:

• Hydrant System: 228 LPM
• Hose Reel: 36 LPM

👉 Total recommended pump capacity:
✔ ~250–300 LPM

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🏭 Recommended Fire Pump Brands

India:

• Kirloskar Fire Pumps
• Crompton Greaves

International:

• Grundfos
• KSB Pumps

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FAQ

Q1: What is minimum fire pump head for G+5 building?

👉 Typically 35–45 m depending on losses.

Q2: How to calculate fire pump capacity?

👉 Based on number of hydrants and flow requirement.

Q3: Is friction loss always required?

👉 Yes, it ensures accurate pump sizing.

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