Design and Installation of Fixed Automatic Sprinkler Fire Extinguishing Systems - Code of Practice

IS 15105 - Scope: Key Formulas, Tables & Specifications

Scope Overview

IS 15105 covers hydraulic design and installation of sprinkler systems, including pipe sizing, orifice plates, and hazard classifications.

Key Tables & Specifications

Important Formulas (General Guidance)

• Orifice Flow Rate (Q):
  [ Q = C_d A \sqrt{2 \Delta P / \rho} ]
  Where:

  • (C_d) = discharge coefficient
  • (A) = orifice area
  • (\Delta P) = pressure drop across orifice
  • (\rho) = fluid density

• Pressure Loss in Pipes (Hazen-Williams):
  [ h_f = 10.67 \times \frac{L}{C^{1.85} d^{4.87}} \times Q^{1.85} ]
  Where:

IS 15105: Key Definitions & Tables Summary

1. Light Hazard Class (Clause 5.1.1)

• Applies to non-industrial occupancies with rooms/corridors ≤ 125 m², bounded by masonry or RCC walls to the roof.
• Examples: Hospitals, Hotels, Libraries, Schools, Offices.
• If area > 125 m² or not fully bounded, classify as Moderate Hazard.

2. Pipe Distribution Losses (Table 1, Clause 4.3.2)

• Details pressure loss calculations for pipe runs.
• Includes pipe size, length, number of turns, equivalent length, and pressure loss (mBars).
• Use total equivalent pipe length and pressure loss for hydraulic design.

3. Orifice Plates (Clause 12.2.3 & Table 16)

• Thickness depends on pipe nominal bore:

  Pipe Nominal Bore (mm)	Orifice Plate Thickness (mm)
  ≤ 80	3
  80 - 150	6
  150 - 200	9

• Use Tables 32 & 33 for orifice size, flow rate, and pressure loss relation.

4. Sprinkler Size & K Factor (Clause 15.3 & Table 35)

• Orifice sizes: 10, 15, 20 mm.

• K factor formula:
  [ K = \frac{Q}{P^{0.5}} ] where
  ( Q ) = flow rate (l/min),
  ( P ) = pressure (bar).

• Typical K factors:

5.

IS 15105: General Requirements - Key Formulas, Tables & Specifications

1. Design Density, Flow Rate & Pressure for High Hazard Installations (Clause 8.2.3.1)

• Use 15 mm (K=80) or 20 mm (K=115) sprinklers.
• Design density (l/min/m²), flow rate (l/min), and pressure (bars) vary with floor area per sprinkler.
• Refer to Tables 6 to 9 for detailed values.

2. Key Tables Summary

3. Pump Selection (Clause 9.1.4, Table 10)

Important Notes:

• When upgrading from moderate to high hazard, use parameters from these tables.
• Pressure values are at the highest sprinkler level.
• Design density is critical for adequate sprinkler coverage.

flowchart LR
    A[Hazard Type] --> B[Select Sprinkler Size & K-factor]
    B --> C[Determine Floor Area per Sprinkler]
    C --> D[Refer Tables 6-9 for Density, Flow & Pressure]
    D --> E[Select Pump Capacity & Delivery Pressure (Table

IS 15105: Classification of Hazards

Hazard Classes (Clauses 11.2.1 to 11.2.3)

Key Specifications:

• Fire Load Density (MJ/m²) is a key parameter for classification.
• Light Hazard: Fire load < 500 MJ/m²
• Moderate Hazard: Fire load between 500 - 2500 MJ/m²
• High Hazard: Fire load > 2500 MJ/m² or presence of highly flammable substances.

Application:

• Classification affects design of fire protection systems (sprinklers, alarms).
• Determines minimum fire resistance ratings and spacing of fire suppression devices.

flowchart LR
    A[Occupancy] --> B{Fire Load Density}
    B -->|< 500 MJ/m²| C[Light Hazard]
    B -->|500-2500 MJ/m²| D[Moderate Hazard]
    B -->|> 2500 MJ/m² or Flammable Materials| E[High Hazard]

Use this classification to select appropriate fire safety measures per IS 15105.

IS 15105: Design Density & Area of Operation (AMAO)

1. Design Density (Clause 3.10):
[ \text{Design Density} = \frac{\text{Discharge of sprinklers (l/min)}}{\text{Area covered (m}^2)} ]

• Unit: l/min/m² (liters per minute per square meter)
• Minimum density of water discharge for sprinkler design.

2. Table 3: Minimum Design Density & AMAO (Clause 8.1)

3. High Hazard Design Parameters (Clause 8.2.3.1):

• Flow rate and pressure depend on floor area per sprinkler and sprinkler K-factor.
• Use Tables 6 to 9 for detailed flow and pressure values for 15 mm (K=80) and 20 mm (K=115) sprinklers.
• Example (Table 6 snippet for 9 l/min/m²):

4. Orifice Plates for Hydraulic Balance (Clause 13.6.1, Table 32)

Summary:

• Use Table 3 for basic

IS 15105: Building Areas to be Sprinkler Protected – Key Specifications

1. Maximum Area Coverage per Sprinkler

2. Extent of Sprinkler Protection (Clause 6.2)

• Specifies areas within buildings that require sprinkler protection based on occupancy and fire hazard.
• Typically includes all areas except small, low-risk zones.

Summary Table for Quick Reference:

Note: For detailed design, refer to the full clauses for exact conditions and exceptions.

flowchart LR
    A[Building Area] --> B{Type of Sprinkler}
    B -->|Sidewall| C[Max Area: 9-17 m²]
    B -->|Other Types| D[Max Area: 12-21 m²]
    A --> E{Storage Rack?}
    E -->|Single Row| F[Max Area: 10 m²]
    E -->|Double Row| G[Refer to Clause 11.2.3.1]

This ensures compliance with IS 15105 for sprinkler design coverage.

IS 15105 - Sprinkler Types and Characteristics

1. Sprinkler Types (Clause 15.2.1)

• Conventional pattern
• Spray pattern
• Ceiling or flush pattern
• Concealed pattern
• Side wall pattern

Selection must conform to Table 34 based on hazard class.

2. Sprinkler Sizes and Hazard Classes (Table 34 Summary)

3. K-Factor and Flow Equation (Clause 15.3)

[ K = \frac{Q}{P^{0.5}} ]

• K = K-factor (l/min·bar^0.5)
• Q = Flow rate through sprinkler (l/min)
• P = Pressure at sprinkler entry (bar)

4. Sprinkler Sizes, Threads & K-Factors (Table 35)

Summary

• Choose sprinkler type per hazard and Table 34.
• Use orifice size 10, 15, or 20 mm.
• Calculate flow with ( Q = K \sqrt{P} ).
• Refer Table 35 for K-factor values and thread sizes.

flowchart LR
    A[Hazard Class] --> B{Sprinkler Type}
    B --> C[Conventional]
    B --> D[Spray]
    B --> E[Ceiling/Flush]
    B --> F[

IS 15105: Hydraulic Calculations & Pipe Sizing Key Points

1. Hydraulic Calculation Inputs (Clause 4.3.3 & 13.1)

• Area Identification & Hazard Class
• Density of Discharge (mm/min)
• Area of Maximum Operation (AMAO) (m²)
• Number of Sprinklers in AMAO
• Sprinkler Orifice Size (mm)
• Max Area per Sprinkler (m²)

2. Sprinkler Data (Clause 4.3.3 b)

• Sprinkler node/reference number
• Nominal K-factor (l/min/bar^0.5)
• Flow rate (l/min)
• Inlet pressure (bar)

3. Pipe Data (Clause 4.3.3 c)

• Pipe node/reference
• Nominal bore (mm)
• Hazen-Williams constant, C (typ. 120 for steel)
• Flow rate (l/min)
• Velocity (m/s)
• Length (m)
• Static head change (m)
• Inlet & outlet pressure (bar)
• Friction loss (bar)
• Flow direction

4. Key Formula: Hazen-Williams Equation for Head Loss

[ h_f = 10.67 \times \frac{L}{C^{1.85} \times d^{4.87}} \times Q^{1.85} ]

Where:

• (h_f) = head loss (m)
• (L) = pipe length (m)
• (C) = Hazen-Williams constant
• (d) = internal diameter (m)
• (Q) = flow rate (m³/s)

5. Velocity Calculation

[ v = \frac{4Q}{\pi d^2} ]

Where:

• (v) = velocity (m/s)
• (Q) = flow rate (m³/s)
• (d) = internal diameter (m)

Diagram: Hydraulic Calculation Workflow

flowchart TD
    A[Define Design Area & Hazard Class] --> B[Calculate AMAO & Sprinkler Count]
    B --> C[Select Sprinkler K-factor & Orifice Size]
    C --> D[Determine Flow & Pressure per

IS 15105 - Fire Pump and Engine Requirements Summary

Fire Pump Capacity & Pressure (Clause 9.1.4, Table 10)

Engine Requirements (Clause 9.3.2.1 & 9.3.2.3)

• Engine Type: Compression ignition, mechanical direct injection.
• Starting: Must start at 7ºC without aids (wicks, ether).
• Cooling: Naturally aspirated, supercharged or turbocharged; air or water cooled with multiple belts for fan/pump drive.
• Operation: Continuous full load for 6 hours at site elevation.
• Governor: Adjustable to maintain speed within ±10% under all loads.
• Instrumentation: Built-in tachometer and hour counter.

Engine Power Rating (Clause 9.3.2.3)

The bare engine horsepower (HP) rating shall be the higher of:

• a) 20% above max brake HP to drive pump at duty point, or
• b) Brake HP to drive pump at 150% of rated discharge.

Key Formula for Engine HP Selection:

[ \text{Engine HP} = \max \left(1.2 \times \text{Brake HP at duty}, \ \text{Brake HP at } 1.5 \times \text{rated discharge}\right) ]

flowchart LR
    A[Nature of Risk] --> B[Select Pump Capacity & Pressure

IS 15105: Key Formulas, Tables & Specifications for Materials and Components

1. Orifice Plates (Clause 12.2.3)

• Use Tables 32 & 33 for orifice size, flow rate, and pressure loss.
• Orifice plate thickness depends on pipe nominal bore (Table 16):

• Orifice design example (Table 32) for 50 & 65 mm pipes:

2. Sprinkler Location (Table 15, Clause 12.1.4)

• Minimum horizontal distance from pipe center line and max height of sprinkler deflector:

3. Pressure Loss in Distribution Pipes (Table 1, Clause 4.3.2)

• Pressure loss calculated by pipe length + equivalent length of turns.
• Pressure drop from orifice plates reduces static head gain.

4. Hazard Classification & Design Densities (Clause 5.1.1 & 8.2.3.1)

• Light hazard: rooms ≤125 m² bounded by masonry/RCC.
• High hazard sprinklers (15 mm K=80) flow & pressure (Tables 6-9):

| Min. Density (l/min/m²) | Flow Rate (l/min) | Pressure at Design Point (Bars) for Various Floor Areas (m²) |

IS 15105: Sprinkler Installation and Spacing - Key Points

1. Sprinkler Coverage and Spacing (Clause 11.2 & 11.13.4)

• Maximum spacing between sprinklers depends on storage category:

  • Category I/II: Horizontal spacing × vertical spacing ≤ 9 m²
  • Category III/IV: Horizontal spacing × vertical spacing ≤ 5 m²

• This ensures adequate water distribution over the hazard area.

2. Precalculated Sprinkler Arrays (Clause 12.4)

• Use standard arrays for pipe sizing and hydraulic calculations.
• Arrays specify sprinkler positions and flow rates for efficient design.

3. Supporting Arrangements (Clause 10.3.15)

• Sprinklers must be supported per Fig. 15 (typical arrangements).
• Supports ensure stability and correct orientation.

Summary Table: Sprinkler Spacing Limits

Formula for Maximum Spacing:

[ S_x \times S_y \leq A_{max} ]

Where:

• (S_x) = horizontal spacing (m)
• (S_y) = vertical spacing (m)
• (A_{max}) = max allowable area (9 or 5 m² depending on category)

flowchart LR
    A[Start: Determine Storage Category] --> B{Category I/II?}
    B -- Yes --> C[Max spacing area = 9 m²]
    B -- No --> D[Max spacing area = 5 m²]
    C --> E[Calculate spacing: Sx × Sy ≤ 9]
    D --> E[Calculate spacing: Sx × Sy ≤ 5]
    E --> F[Design sprinkler layout accordingly]

For detailed pipe sizing and hydraulic design, refer to Clause 12 and standard hydraulic calculation methods.

Hydraulic Balancing & Orifice Plates (IS 15105)

Key Specifications (Clause 12.2.1)

• Orifice diameter ≥ 0.5 × internal pipe diameter.
• Applicable only for pipes ≥ 50 mm nominal bore.
• Material: Brass or stainless steel, plain central hole, burr-free.
• Thickness as per Table 16 (refer IS 15105).
• Identification tag with nominal pipe size & orifice K factor.

Design of Orifice Plates (Clause 13.6.1 & Table 32)

(Partial table for key values; use full Table 32 for detailed design)

Important Formula

The orifice K factor relates pressure loss to flow rate and is used in hydraulic balancing:

[ \Delta P = K \times \frac{\rho V^2}{2} ]

• (\Delta P) = pressure loss (Pa)
• (K) = orifice K factor (from Table 32)
• (\rho) = fluid density (kg/m³)
• (V) = velocity (m/s)

Summary

• Select orifice diameter from Table 32 based on desired pressure loss.
• Confirm orifice diameter ≥ 0.5 × pipe internal diameter.
• Use K factor for pressure loss calculations in balancing.
• Ensure material & thickness per IS 15105.

flowchart LR
    A[Pipe Diameter ≥ 50mm] --> B[Select Orifice Diameter ≥ 0.5 × Pipe ID]
    B --> C[Refer Table 32 for Orifice Diameter & K

IS 15105: Miscellaneous Design Parameters - Key Formulas & Tables

1. Orifice Plate Design (Clause 13.6.1, Table 32)

• Use these for hydraulic balance in medium grade pipes (IS 1239 sizes 50 & 65 mm).
• K Factor relates to pressure loss and flow characteristics.

2. Pipe Pressure Loss & Equivalent Length (Table 1, Clause 4.3.2)

• Total equivalent pipe length = Actual pipe length + Equivalent length of fittings/turns.
• Pressure loss (mBar) calculated at design flow rate.
• Use equivalent length of turns = 2 m per elbow/bend/tee.

3. Light Hazard Installation Parameters

• Light Hazard Class: Rooms ≤125 m² bounded by masonry/RCC walls (Clause 5.1.1).
• Max Pipe Length & Sprinkler Count (Table 18):

• Pressure Loss per Unit Length (Table 20):

IS 15105: Pressure and Flow Measurement Devices - Key Points

1. Pressure and Flow Requirements (Clauses 8.2 & 8.3.1)

• Devices must measure pressure and flow accurately to ensure system performance.
• Flow rate and pressure loss relationships are critical for device sizing.

2. Orifice Plates (Clause 12.2.3)

• Flow rate and pressure loss are calculated using Tables 32 and 33 (not fully provided here).
• Orifice size directly affects flow and pressure drop.

3. Orifice Plate Thickness (Table 16, Clause 12.2.1)

4. Sprinkler Location Alongside Feed Pipes > 65 mm (Table 15, Clause 12.1.4)

Note: Dimensions may be interpolated.

5. Pressure Gauges (Clause 14.10)

• Must be suitable for the pressure range and environment.
• Accuracy and durability per system requirements.

Summary Formula for Orifice Flow (General):

[ Q = C_d A \sqrt{\frac{2 \Delta P}{\rho}} ]

Where:

• ( Q ) = Flow rate
• ( C_d ) = Discharge coefficient (from tables)
• ( A ) = Orifice area
• ( \Delta P ) = Pressure drop across orifice
• ( \rho ) = Fluid density

flowchart LR
    A[Pressure Source] --> B[Orifice Plate]
    B --> C[Pressure Drop \(\Delta P\)]
    C --> D[Flow

IS 15105: Special Sprinkler Applications - Key Formulas & Tables

1. Sprinkler Location Near Large Pipes (Table 15, Clause 12.1.4)

Minimum horizontal distance from pipe center line vs. max deflector height:

2. Orifice Plate Thickness (Table 16, Clause 12.2.1)

3. Orifice Plate Flow & Pressure (Clause 12.2.3)

• Use Tables 32 & 33 for orifice size, flow rate, and pressure loss relations.
• Formula (general):

[ Q = K \sqrt{P} ]

Where:

• (Q) = Flow rate (l/min)
• (K) = Orifice coefficient (depends on orifice size)
• (P) = Pressure loss (bar)

4. High Hazard Sprinkler Design (Clause 8.2.3.1 & Tables 6-9)

• Design density: 9.0 to 30 l/min/m² depending on hazard.
• Sprinkler K-factors: 80 (15 mm) & 115 (20 mm).
• Flow rate and pressure depend on floor area per sprinkler and hazard class.

Example (Table 6 for 15 mm K=80 Sprinklers):

IS 15105: Corrosion Protection Key Points

1. Corrosion Protection Specifications:

• Welded fittings must be galvanised or suitably coated after welding to resist chemical/electrolytic corrosion (Clause 10.2.3).
• In corrosive vapour areas, sprinklers require corrosion-resistant coatings; petroleum jelly can be applied except on fusible links or glass bulb bodies (Clause 15.6.4).
• Pipework in corrosive environments should be stainless steel or adequately protected (Clause 10.3.9).

2. Protective Coating Recommendations:

• Use galvanisation or special coatings based on the environment.
• Avoid coating fusible links and glass bulb bodies to maintain functionality.

3. Related Tables (For Reference):

(From Table 16, Clause 12.2.1)

Summary Diagram: Corrosion Protection Workflow

flowchart TD
    A[Welded Fittings] --> B{Environment}
    B -->|Corrosive| C[Galvanise or Coat]
    B -->|Non-Corrosive| D[Standard Protection]
    C --> E[Apply Coating Post-Welding]
    E --> F[Check Sprinkler Components]
    F --> G{Component Type}
    G -->|Fusible Link/Glass Bulb| H[No Coating]
    G -->|Others| I[Apply Petroleum Jelly or Coating]

Note: Always select corrosion protection based on specific chemical exposure and environmental conditions per IS 15105 guidelines.

IS 15105 - Maintenance of Sprinkler Installation (Clause 17 & Table 38)

Key Maintenance Activities & Frequencies

Important Notes:

• Alarm gong assembly must be checked every 3 months.
• Regular hydraulic performance checks and physical inspection for pipe support and orientation are essential.
• Maintain detailed periodic maintenance charts for system reliability.

Visual Summary (Mermaid Diagram):

graph TD
  A[Sprinkler Installation Maintenance] --> B[Daily Checks]
  A --> C[Weekly Checks]
  A --> D[Quarterly Checks]
  A --> E[Annual

IS 15105: Testing & Inspection Procedures - Key Points

Initial & Periodical Testing (Clauses 18.2 & 17.6)

• Initial testing ensures system compliance before commissioning.
• Periodical testing maintains system reliability and performance.

Periodical Testing & Maintenance Chart (Table 38, Clause 17.6.5.3)

Alarm Gong (Clause 18.6.2)

• Check audibility ≥ 85 dB above background noise.
• Functionality tested quarterly or as per local practice.

Summary of Important Specifications:

• Daily running tests for pumps and engines (5 min).
• Weekly checks for reservoir level, gland packing, battery status, motor lubrication, and alarm valves.
• Quarterly lubrication and cleaning.
• Annual flow tests and calibration of gauges.
• Overhaul every 2 years.

Diagram: Periodical Testing Frequency Overview

gantt
    title Periodical Testing & Maintenance Schedule
    dateFormat  YYYY-MM-DD
    section Daily
    Pump Running Test         :active, daily, 2024-01-01, 1d
    Engine Running           :active, daily, 2024-01-01, 1d
    Gauge Pressure Check    :active, daily, 2024-01-01, 1d