Design and Installation of Fixed Automatic High and Medium Velocity Water Spray System - Code of Practice

IS 15325 - Scope: Key Tables & Specifications

1. Pipe Sizing for Water Spray Rings (Clause 6.5.5.1)

2. Sprayer Spacing & Angles (Clause 6.5.3.2)

• Sprayers spaced based on cone angle and distance from tank surface.
• Example longitudinal spacing for 90° cone angle sprayer at 0.65m from tank:

• Use sprayer application charts (C, D, E) for 'K' factor vs vessel diameter.
• If exact 'K' factor unavailable, select next higher.

3. Electrical Clearance (Clause 5.2.1.5)

• Clearance is air distance between spray components and live parts.
• For installations protected against overvoltages, reduced clearances apply (see Table 1).

Summary Diagram: Pipe Sizing Decision Flow

flowchart TD
    A[Determine Flow Rate] --> B{Top or Bottom Ring?}
    B

IS 15325 Key Definitions & Specifications Summary

1. Sprayer Distribution & Spacing (Clause 6.5.3.2)

• Sprayers arranged in horizontal rows spaced based on cone angle and distance from tank surface.
• Longitudinal spacing (m) depends on sprayer angle and distance from tank (0.65m, 0.55m, 0.45m).

• K-factor relates sprayer discharge rate to vessel diameter; use next higher K-factor if exact not available.
• Sprayer application charts (C, D, E) link K-factor and vessel diameter for different sprayer distances.

2. Pipe Sizing for Rings (Clause 6.5.5.1)

• Top ring pipe size depends on total sprayer flow between vertical feed pipes:

• Bottom ring pipe size depends on average flow in module ≤10m:

3. Design Checks (Clause 6.7.1.9)

• Cross-check vessel drawings with:
  • Plan, elevation, site plan
  • Protrusions (valves, drains,

IS 15325: Principle of Operation for Transformer Spray System

Key Points from Clauses:

• Sprayer Distribution (6.5.3.2):
  Sprayers are arranged in horizontal rows with spacing depending on the cone angle and distance from tank surface (0.45m, 0.55m, 0.65m).
  Use the following table for longitudinal spacing (m) based on cone angle and sprayer distance:

• K-Factor & Cone Angle:
  Sprayer charts (C, D, E) relate K-factor (spray intensity) to vessel diameter and sprayer distance. If exact K-factor unavailable, use next higher value for adequate coverage.

• Pressure Requirement (6.9.3):
  Adequate pressure must be maintained for effective spray coverage; refer to detailed design for pressure values.

• Design Inputs (5.2.1.3):
  Cross-check transformer dimensions, oil quantity, equipment layout, and sprayer characteristics (K-factor, cone angle, LPM discharge, effective reach) for system design.

Summary Formula for Sprayer Spacing:

[ \text{Spacing} = f(\text{Cone Angle}, \text{Distance from Tank}) ]

Use the above table values directly for design.

Conceptual Mermaid Diagram:

flowchart LR
    A[Transformer Dimensions] --> B[Select Sprayer Cone Angle]
    B --> C[Determine Distance from Tank Surface]
    C --> D[Use Table for Sprayer Spacing]
    D --> E[Select Sprayer with Appropriate K-factor]
    E -->

IS 15325: System Components and Materials – Key Specifications

1. Electrical Clearance (Clause 5.2.1.5)

Minimum air clearance between water spray components and live electrical parts to avoid hazards:

Note: Special care near transformers for spray pipe layout.

2. Pipe Sizing for Water Spray Systems (Clause 6.5.5.1)

• Top Ring Pipe Diameter (Table 2):

• Bottom Ring Pipe Diameter (Table 3):

3. Additional Notes

• System design must ensure hydraulic efficiency and maintain required clearances.
• Piping and hydraulics (Clause 6.9.5) must support flow rates and pressure as per design.

flowchart TD
    A[Water Spray System] --> B[Top Ring Pipes]
    A --> C[Bottom Ring Pipes]
    B -->

IS 15325: Electrical Clearances and Safety (Clause 5.2.1.5)

Key points on Electrical Clearances:

• Clearance is the air gap between live uninsulated electrical parts and water spray equipment.
• Minimum clearances ensure safety during water spray system operation.
• Values comply with the National Electrical Code of BIS.

Table 1: Minimum Electrical Clearances (mm)

Note: Clearance applies to live parts at other than ground potential.

Additional Safety Specifications:

• Transformer Protection:
  • Obstructed parts require separate water spray projectors.
  • Pipes extended >600 mm need separate supports.
• Fire Barrier Walls:
  • 355 mm brick or 200 mm RCC, extending 600 mm above equipment.
  • Minimum clear separation depends on transformer oil capacity (6 m to 15 m).

Summary Diagram (Clearance Concept)

graph LR
  A[Live Electrical Part] --- B[Air Clearance (min. distance)]
  B --- C[Water Spray Equipment]
  B --- D[Safety Zone]

Use these clearances strictly to prevent electrical hazards during water spray firefighting operations.

IS 15325: Key Design & Installation Requirements for Transformer Spray Systems

1. Design Information to Cross-Check (Clause 5.2.1.3)

• Transformer dimensions: Length, Width, Height
• Bushing location & height
• Oil conservator tank size & location
• Switch boxes, tap changers, explosion vents, piping obstructions
• Transformer ratings: kVA, Voltage, Oil quantity
• Cable routing & floor details (concrete, asphalt, etc.)
• Elevation above grade & barrier walls
• Radiator/cooler bank siting
• Pipe colors for protection/detection
• Sprayer characteristics: K-factor, cone angle, discharge (LPM), reach

2. Installation Requirements (Clause 4.5.2)

| Indicators | Show open/closed valve position | | Priming | Facility to prime valve seat space | | Leakage | Prevent backflow into instrument air | | Instructions | Durable plate with startup/shutdown |

3. Pipe Sizing for Spray Rings (Clause 6.5.5.1)

Top Ring Pipe Size (Table 2):

Bottom Ring Pipe Size (Table 3):

IS 15325: Inspection, Testing & Maintenance Key Points

1. Periodical Testing and Maintenance (Clause 7.2 & 7.3)

2. Operating Instructions (Clause 7.2.1.2)

• Operating & maintenance instructions must be available at control equipment and fire station.
• Trained personnel should be assigned for operation and maintenance.

3. Electrical Clearance (Clause 5.2.1.5, Table 1)

IS 15325 Key Specifications for Water Supply and Pumping Capacity

1. Effective Reservoir/Tank Capacity (Clause 6.2 & 6.9.6)

• Above top of pump casing (positive suction):

  • If flammable fluid/solvent hold-up < 200 m³ at one location:
    Capacity ≥ 90 minutes of installed pumping capacity
  • If hold-up > 200 m³ at one location:
    Capacity ≥ 150 minutes of installed pumping capacity

• Above foot valve seat (negative suction):
  Capacity ≥ 40 minutes of aggregate pumping capacity for the spray system.

2. Location Definition (Clause 6.2)

• All storage vessels within 50 m are considered one location for capacity calculation.

Summary Table

Important Notes

• Installed pumping capacity = sum of capacities of all pumps serving the system.
• Ensure effective capacity is exclusive (deduct unusable volume).
• Capacity measured above pump casing or foot valve seat depending on suction type.

flowchart LR
    A[Storage Vessels] -->|Within 50 m| B(Location)
    B --> C{Hold-up Volume}
    C -->|< 200 m³| D[Reservoir Capacity = 90 min pump capacity]
    C -->|> 200 m³| E[Reservoir Capacity = 150 min pump capacity]
    F[Spray System (Negative Suction)] --> G[Reservoir Capacity = 40 min aggregate pump capacity]

This ensures adequate water supply for firefighting and safety systems as per IS 15325.

Protection of Specific Hazards per IS 15325 focuses on maintaining safe electrical clearances around water spray and fire protection equipment to prevent electrical hazards.

Key Points from IS 15325:

1. Electrical Clearance (Clause 5.2.1.5 & Table 1)

• Clearance = air distance between water spray equipment (pipes, nozzles) and live uninsulated electrical parts.
• Minimum clearances depend on system voltage and overvoltage protection.
• Clearances ensure safety during normal and fire-fighting operations.

2. Equipment Protection (Clause 6.4.5.7)

• Equipment must be located to maintain these clearances.
• Special care for transformers (indoor/outdoor) affected by spray networks.

3. Structural Protection (Clause 6.4.6)

• Structures must be designed to protect critical equipment from fire hazards and water spray damage.

Summary:

• Maintain minimum electrical clearances per Table 1.
• Locate equipment to avoid spray contact with live parts.
• Design structures to protect equipment from hazards.

flowchart TD
    A[Water Spray Equipment] -->|Maintain Clearance| B[Live Electrical Components]
    B --> C{Voltage Level}
    C -->|Low Voltage| D[Min Clearance 150-700 mm]
    C -->|High Voltage| E[Min Clearance 700-3500 mm]
    F[Transformer] -.->|Special Clearance| B
    G[Structural Protection] --> B

This ensures safety against electrical hazards

IS 15325: Fire Barrier Walls – Key Specifications & Tables

1. Fire Barrier Wall Construction (Clause 5.2.3.5a)

• Material & Thickness:
  • Brick wall: 355 mm thick
  • RCC wall: 200 mm thick
• Height: Extend at least 600 mm above highest equipment point to be protected.

2. Clear Separating Distances (Clause 5.2.3.5b)

• If spacing is less than above, fire barrier walls are mandatory.

3. Aggregate Water Demand (Clause 5.2.3.5c)

• Without walls or clear distances, water flow and pressure must be designed for the aggregate fire demand of all transformers combined.

4. Fire Barrier Definition (Clause 3.12)

• Continuous wall/floor designed to limit fire spread.

Summary Diagram: Fire Barrier Wall & Equipment Layout

graph LR
  A[Transformer 1] ---|6m+| B[Transformer 2]
  B ---|6m+| C[Transformer 3]
  subgraph Fire Barrier Wall
    FW[355mm Brick / 200mm RCC Wall]
  end
  A --- FW --- B

Additional Notes:

• Structural steel exposed to flame should be wetted at ≥ 10.2 l/min/m² (Clause 6.4.6.3).
• Sprinkler pipes must be supported structurally to maintain performance under fire (Clause 6.4.7.1).

This ensures fire safety by preventing fire spread between transformers via physical barriers or adequate spacing, supported by proper water spray design.

IS 15325: Zoning and Control of Water Spray Areas – Key Points

1. Sprayer Spacing (Clause 6.5.3.2a)

• Longitudinal spacing of sprayers (m) depends on discharge angle and distance from tank surface:

2. Sprayer Application Charts (6.5.3.2b)

• Charts C, D, E relate K-factor (spray intensity) to tank diameter and sprayer distance.
• If exact K-factor unavailable, use next higher value.
• Interpolation allowed if sprayer distance varies.

3. Protection Density (Clause 6.4.2)

• Water application density depends on:
  • Type of flammable liquid
  • Protection objective (e.g., controlled burning, exposure protection)
  • Ceiling height and fire area
  • Container type

4. Piping & Support (Clause 6.4.7.1)

• Pipes must be supported by building structure capable of holding water-filled pipes under fire conditions without impairing sprayer performance.

Summary Formula for Sprayer Spacing (approximate):

[ S = f(\theta, d) ]

Where:

• ( S ) = Sprayer spacing (m)
• ( \theta ) = Discharge angle (°)
• ( d ) = Distance from tank surface (m), typically 0.45, 0.55, or 0.65 m

Conceptual Mermaid Diagram: Sprayer Layout

graph TD
    A[Tank Surface] -->|0.45m| B[Sprayer Row 1]
    A -->|

IS 15325: Piping Layout and Supports - Key Points

1. Piping Layout (Clauses 6.5.4, 6.6.4, 6.4.7)

• Layout must ensure minimum stress on pipes due to thermal expansion.
• Provide adequate clearance for insulation, maintenance, and thermal movement.
• Avoid sharp bends; use long-radius bends to reduce stress.
• Supports should allow axial movement where thermal expansion occurs.
• Maintain proper slope for drainage and venting.

2. Pipe Supports (Clauses 6.7.3, 6.5.4)

• Supports must carry weight of pipe + fluid + insulation.
• Types: rigid supports, spring supports, guides, anchors.
• Spacing of supports depends on pipe size and material (refer to Table below).

3. Typical Support Spacing (Example Table)

4. Key Formulas

• Load on Support (W):
  [ W = W_{pipe} + W_{fluid} + W_{insulation} ]

• Thermal Expansion (ΔL):
  [ \Delta L = \alpha \times L \times \Delta T ]
  where
  (\alpha) = coefficient of thermal expansion,
  (L) = length of pipe,
  (\Delta T) = temperature change.

flowchart LR
    A[Piping Layout] --> B[Allow Thermal Expansion]
    A --> C[Provide Clearance]
    B --> D[Use Expansion Loops]
    C --> E[Maintenance Access]
    F[Supports] --> G[Carry Loads]
    F --> H[Allow Movement]
    G --> I[Spacing per Diameter]

Summary: IS 15325 emphasizes proper layout to minimize stress and specifies support types and spacing to safely carry loads and accommodate thermal

IS 15325 Key Points on Detectors and Sprinkler Heads

1. Detection System (Clause 4.3)

• Detects fire by sensing smoke, heat, or radiation.
• Sprinklers act as detectors in most water spray systems.
• Specialized detectors (smoke, ROR) acceptable if design details provided.
• Applications: general areas, vessels, transformers, spot protection.

2. Sprinkler & Sprayer Specifications

Piping & Support (Clause 6.4.7.1)

• Pipes must be supported by building structure.
• Structure must support water-filled pipes and not impair sprinkler performance during fire.

Sprayer Discharge Angle vs Height (Clause 6.4.7.1)

• Discharge angle affects coverage; typical 100° angle used for sprayers below 1 m height.
• For heights above 13 m, deflectors on sprinklers are mandatory.

Sprayer Spacing (Clause 6.5.3.2)

• Use next higher K-factor if exact not available.
• Sprayer application charts relate K-factor, vessel diameter, and sprayer distance.

3. Design Considerations (Clause 6.4.3.8)

• Cross-check detailed drawings: layout, structure, piping, valves.
• Hydraulic calculations require node drawings.
• Include characteristic curves of sprayers/sprinklers (K-factor, orifice size, spray angle).
• Provide chemical properties of liquids handled.
• Document design philosophy clearly.

Typical Sprinkler Design Parameters

| Parameter | Typical Value/Note | |-----------------------|

IS 15325: Spare Parts and Equipment Reliability - Key Points

1. Spare Parts Requirements (Clause 4.2.3.13)

• Fuel filters, elements & seals: 2 sets
• Lubricating oil filters, elements & seals: 2 sets
• Belts (if used): 2 sets
• Complete set of engine joints, gaskets & hoses: 1 set
• Injector nozzles: 2 nos.
• Piston rings (per cylinder): 1 complete set
• Valves: 1 inlet valve & 1 exhaust valve

2. Equipment Protection (Clause 6.4.5.7)

• Ensure proper protective measures are in place to maintain reliability and prevent damage.

3. Spare Parts Readiness (Clause 4.2.2.19)

• Keep necessary spare parts including a set of fuses in a glass-fronted box at pump house, ready for immediate use.

4. Sprayer Distribution & Reliability (Clause 6.5.3.2)

• Sprayers spaced according to discharge angle and distance from tank.

• Use higher K-factor if exact match unavailable.
• Protect vessel ends by appropriate sprayer placement.

Summary Diagram: Spare Parts Supply Flow

flowchart LR
    A[Engine System] --> B{Spare Parts Supplied}
    B --> C[Fuel Filters (2 sets)]
    B --> D[Oil Filters (2 sets)]
    B --> E[Belts (2 sets)]
    B --> F[Engine Gaskets & H

IS 15325 - Key Details on Annexes and Committee Composition

• Annex A: Lists referenced standards incorporated by reference. These standards' editions at publication are binding, but users should check for the latest versions.

  • Example: Fire safety codes, material standards, etc.

• Annex B: Details the Committee responsible for the standard formulation:

  • Fire Fighting Sectional Committee, CED 22
  • This committee includes experts from government, industry, and academia specializing in fire safety.

• Clause 5.2.3: Refers to General Layout and Design principles, but specifics are in the main text, not annexes.

Summary Table

For detailed formulas or design tables, refer to the main clauses of IS 15325 or related referenced standards in Annex A.