Design and Installation of Fixed Automatic High and Medium Velocity Water Spray System - Code of Practice
2003 Edition

IS 15325 - Scope Overview and Key Tables

1. Water Spray Ring Pipe Dimensions (Clause 6.5.5.1)

2. Sprayer Arrangement and Angles (Clause 6.5.3.2)

• Sprayers are positioned based on the spray cone angle and the distance from the tank surface.
• For instance, longitudinal spacing for a sprayer with a 90° cone angle at 0.65 m from the tank is 1.45 m.

• Reference sprayer application charts (C, D, E) to match 'K' factor and vessel size.
• If an exact 'K' factor is not found, select the next higher value.

3. Electrical Safety Clearances (Clause 5.2.1.5)

• Clearance refers to the air distance between spray components and energized parts.
• Reduced clearances apply when overvoltage protection is in place (see Table 1).

Visual Flow Diagram: Pipe Sizing Decisions

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

Essential Definitions and Specifications in IS 15325

1. Sprayer Distribution and Spacing (Clause 6.5.3.2)

• Sprayers are arranged in horizontal rows with spacing determined by the cone angle and the distance from the tank surface.
• Longitudinal spacing (meters) varies with sprayer angle and distances of 0.65 m, 0.55 m, and 0.45 m from the tank.

• 'K-factor' indicates sprayer discharge rate relative to vessel diameter; select the next higher if exact value is unavailable.
• Sprayer application charts relate K-factor and vessel size for different distances.

2. Pipe Sizing for Spray Rings (Clause 6.5.5.1)

• Top ring pipe sizes depend on total flow between vertical feed pipes:

• Bottom ring pipe sizes depend on average flow over modules ≤10m:

3. Design Verification (Clause 6.7.1.9)

• Verify vessel drawings with plans, elevations, site layouts, and note protrusions such as valves and drains.

IS 15325: Operation Fundamentals for Transformer Water Spray Systems

Highlights from Clauses:

• Sprayer Layout (6.5.3.2):
  Sprayers are positioned in horizontal rows with spacing based on cone angle and distance from tank surface (0.45 m, 0.55 m, 0.65 m).

• K-Factor & Cone Angle:
  Sprayer charts (C, D, E) connect K-factor (spray output) to vessel diameter and sprayer distance. Use the next higher K-factor if exact is not found.

• Pressure Needs (6.9.3):
  Maintain sufficient pressure for effective spray coverage; consult detailed design for values.

• Design Inputs (5.2.1.3):
  Cross-check transformer size, oil volume, layout, and sprayer parameters (K-factor, cone angle, discharge rate, effective reach).

Formula for Sprayer Spacing:

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

Use tabulated values for calculations.

Conceptual Flowchart:

flowchart LR
    A[Transformer Size] --> B[Choose Sprayer Cone Angle]
    B --> C[Measure Distance from Tank Surface]
    C --> D[Refer Table for Spacing]
    D --> E[Select Sprayer with Suitable K-factor]
    E -->

IS 15325: System Components and Material Requirements

1. Electrical Clearance Requirements (Clause 5.2.1.5)

Minimum air gap between water spray parts and energized electrical components:

Note: Extra caution required near transformers for pipe placement.

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

• Upper Ring Pipe Sizes:

• Lower Ring Pipe Sizes:

3. Additional Design Notes

• System design must ensure hydraulic efficiency and maintain all required clearances.
• Piping and hydraulic design (Clause 6.9.5) must support specified flow rates and pressures.

flowchart TD
    A[Water Spray System] --> B[Upper Ring Pipes]
    A --> C[Lower Ring Pipes]
    B -->

IS 15325: Electrical Clearances and Safety Measures (Clause 5.2.1.5)

Key Notes on Electrical Clearances:

• Clearance denotes the air gap between energized, uninsulated electrical elements and water spray apparatus.
• Minimum clearance distances are essential for safe operation during activation of water spray systems.
• These values conform to BIS National Electrical Code standards.

Table 1: Minimum Air Clearance Distances (mm)

Note: Applies to live parts not at ground potential.

Additional Safety Requirements:

• Transformer Protection:
  • Obstructed areas require dedicated water spray nozzles.
  • Pipes extending more than 600 mm must have independent supports.
• Fire Barrier Walls:
  • Constructed with 355 mm brick or 200 mm RCC, extending at least 600 mm above protected equipment.
  • Minimum spacing varies with transformer oil volume, ranging from 6 m to 15 m.

Conceptual Clearance Diagram

graph LR
  A[Live Electrical Component] --- B[Minimum Air Gap]
  B --- C[Water Spray System]
  B --- D[Safety Zone]

Strict adherence to these clearance distances is critical to prevent electrical hazards during firefighting operations.

IS 15325: Essential Design and Installation Guidelines for Transformer Spray Systems

1. Design Data Validation (Clause 5.2.1.3)

• Transformer measurements: length, width, height
• Location and height of bushings
• Dimensions and position of oil conservator tanks
• Switch boxes, tap changers, explosion vents, and piping obstructions
• Transformer ratings including kVA, voltage, and oil volume
• Cable pathways and floor type (concrete, asphalt, etc.)
• Height above ground and fire barrier wall details
• Position of radiator or cooler banks
• Color coding for pipes used in protection and detection
• Sprayer characteristics: K-factor, cone angle, flow rate (LPM), reach

2. Installation Criteria (Clause 4.5.2)

| Indicators | Show valve position (open/closed) | | Priming Facility | To prime valve seat space | | Leakage Prevention | Prevent backflow into instrument air | | Instruction Plate | Durable signage with startup and shutdown steps |

3. Pipe Dimensions for Spray Rings (Clause 6.5.5.1)

Upper Ring Pipe Diameter (Table 2):

Lower Ring Pipe Diameter (Table 3):

IS 15325: Core Guidelines for Inspection, Testing, and Maintenance

1. Routine Testing and Maintenance (Clauses 7.2 & 7.3)

2. Operating Guidelines (Clause 7.2.1.2)

• Operating and maintenance manuals must be accessible at control points and fire stations.
• Trained staff should be responsible for system operation and upkeep.

3. Electrical Clearance Checks (Clause 5.2.1.5, Table 1)

IS 15325: Key Specifications for Water Storage and Pumping Capacity

1. Required Effective Reservoir Volume (Clauses 6.2 & 6.9.6)

• For positive suction (above pump casing):

  • If flammable fluid accumulation is less than 200 m³ at a single location, reservoir capacity must cover at least 90 minutes of the total pump output.
  • If fluid accumulation exceeds 200 m³, capacity must cover a minimum of 150 minutes of pump output.

• For negative suction (above foot valve seat):

  • Reservoir volume must provide at least 40 minutes of total pumping capacity.

2. Location Definition (Clause 6.2)

• All storage tanks within 50 meters are considered one location for capacity calculations.

Summary Table

Notes

• Total pump capacity is the combined output of all pumps serving the system.
• Effective capacity excludes unusable storage volumes.
• Capacity calculations depend on the suction type (positive or negative).

flowchart LR
    A[Storage Tanks] -->|Within 50m| B[Location Defined]
    B --> C{Fluid Volume}
    C -->|< 200 m³| D[Reservoir Capacity = 90 min pump output]
    C -->|> 200 m³| E[Reservoir Capacity = 150 min pump output]
    F[Negative Suction Spray System] --> G[Reservoir Capacity = 40 min pump output]

This standard ensures sufficient water availability for firefighting and protection systems.

Specific Hazard Protection per IS 15325 emphasizes maintaining safe electrical clearances around water spray and fire protection equipment to avoid electrical dangers.

Highlights:

1. Electrical Clearance (Clause 5.2.1.5 & Table 1)

• Clearance is the air gap between water spray equipment and energized, uninsulated electrical parts.
• Minimum clearance values depend on operating voltage and presence of overvoltage protection.
• These clearances ensure operational safety during firefighting.

2. Equipment Placement (Clause 6.4.5.7)

• Position equipment to maintain required clearances.
• Special considerations apply for indoor and outdoor transformers affected by spray systems.

3. Structural Safeguards (Clause 6.4.6)

• Structures must be designed to shield critical equipment from fire and spray damage.

Summary:

• Maintain minimum electrical clearances as specified.
• Arrange equipment to prevent spray contact with energized parts.
• Employ structural measures to protect vital equipment.

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

These measures reduce electrical hazards during fire events.

IS 15325: Fire Barrier Wall Requirements and Tables

1. Construction of Fire Barrier Walls (Clause 5.2.3.5a)

• Materials and Thickness:
  • Brick: 355 mm thick
  • Reinforced Cement Concrete (RCC): 200 mm thick
• Height: Must extend at least 600 mm above the tallest equipment being protected.

2. Minimum Separation Distances (Clause 5.2.3.5b)

• Fire barrier walls are mandatory if spacing is less than these values.

3. Water Demand for Multiple Transformers (Clause 5.2.3.5c)

• If walls or clearances are insufficient, water flow and pressure must be sized for the combined fire demand.

4. Definition of Fire Barrier (Clause 3.12)

• A continuous physical wall or floor designed to restrict the spread of fire.

Diagram: Fire Barrier and Equipment Arrangement

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

Additional Notes:

• Structural steel exposed to flames should be wetted at a minimum rate of 10.2 liters/min/m² (Clause 6.4.6.3).
• Sprinkler piping should be structurally supported to maintain integrity during fire (Clause 6.4.7.1).

These provisions prevent fire propagation between transformers through physical barriers or adequate spacing combined with water spray protection.

IS 15325: Guidelines on Zoning and Water Spray Area Management

1. Sprayer Spacing Rules (Clause 6.5.3.2a)

• Longitudinal spacing of sprayers depends on spray angle and distance from the tank surface:

2. Sprayer Application Charts (Clause 6.5.3.2b)

• Charts C, D, and E relate the K-factor to tank diameter and sprayer distance.
• Use the next higher K-factor if the exact is unavailable.
• Interpolation is permitted if sprayer distances vary.

3. Water Application Density (Clause 6.4.2)

• Density depends on:
  • Type of flammable liquid
  • Protection goals (e.g., controlled burning, exposure protection)
  • Ceiling height and fire area
  • Type of container

4. Piping and Structural Supports (Clause 6.4.7.1)

• Pipes must be supported by building structures capable of bearing water-filled pipes during fire without impairing sprinkler function.

Approximate Sprayer Spacing Formula:

[ S = f(\theta, d) ]

Where:

• ( S ) = Sprayer spacing in meters
• ( \theta ) = Spray discharge angle in degrees
• ( d ) = Distance from tank surface in meters (0.45, 0.55, or 0.65 m)

Conceptual Diagram: Sprayer Placement

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

IS 15325: Guidelines for Piping Layout and Support Structures

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

• Design layout to minimize stress on pipes from thermal expansion.
• Provide adequate clearance for insulation, maintenance, and thermal movement.
• Avoid sharp bends; employ long-radius bends to reduce stress.
• Supports should accommodate axial expansion where thermal movement occurs.
• Maintain appropriate slope for drainage and venting.

2. Pipe Support Types (Clauses 6.7.3, 6.5.4)

• Supports must bear the weight of the pipe, fluid inside, and insulation.
• Support types include rigid supports, springs, guides, and anchors.
• Support spacing depends on pipe diameter and material.

3. Typical Support Spacing Examples

4. Formulas

• Load on Support (W):

[ W = W_{pipe} + W_{fluid} + W_{insulation} ]

• Thermal Expansion (( \Delta L )):

[ \Delta L = \alpha L \Delta T ]

where ( \alpha ) is coefficient of thermal expansion, ( L ) is pipe length, and ( \Delta T ) is temperature change.

flowchart LR
    A[Piping Design] --> B[Allow for Thermal Expansion]
    A --> C[Provide Adequate Clearance]
    B --> D[Use Expansion Loops]
    C --> E[Access for Maintenance]
    F[Supports] --> G[Carry Loads]
    F --> H[Permit Movement]
    G --> I[Spacing Based on Diameter]

Summary: The standard emphasizes a layout that reduces stress and specifies support types and spacing to ensure structural integrity and accommodate thermal effects.

IS 15325: Key Points on Detectors and Sprinkler Heads

1. Fire Detection Systems (Clause 4.3)

• Detect fires by sensing smoke, heat, or radiation.
• Sprinklers often serve as detectors in water spray systems.
• Specialized detectors (smoke, rate-of-rise) are permitted if design details are provided.
• Applicable in general areas, vessels, transformers, and spot protection.

2. Sprinkler and Sprayer Details

Piping and Support (Clause 6.4.7.1)

• Pipes must be supported by building structures.
• Structures should support water-filled pipes without compromising sprinkler operation during fires.

Sprayer Discharge Angles and Heights (Clause 6.4.7.1)

• Discharge angle affects coverage; a typical 100° angle is used for sprayers below 1 m height.
• Sprinklers above 13 m height require deflectors.

Sprayer Spacing (Clause 6.5.3.2)

• Use next higher K-factor if exact value is unavailable.
• Sprayer charts relate K-factor, vessel diameter, and sprayer distance.

3. Design Considerations (Clause 6.4.3.8)

• Cross-check detailed drawings including layouts, structure, piping, and valves.
• Hydraulic calculations require node diagrams.
• Provide sprayer/sprinkler characteristic curves (K-factor, orifice size, spray angle).
• Include chemical properties of handled liquids.
• Clearly document design philosophy.

Typical Sprinkler Design Parameters

IS 15325: Spare Parts and Equipment Dependability - Key Highlights

1. Spare Parts Inventory (Clause 4.2.3.13)

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

2. Equipment Protection Measures (Clause 6.4.5.7)

• Implement protective measures to ensure reliability and prevent damage.

3. Spare Parts Availability (Clause 4.2.2.19)

• Keep essential spare parts, including a set of fuses, in a glass-fronted cabinet at the pump house for immediate use.

4. Sprayer Arrangement and Reliability (Clause 6.5.3.2)

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

• Select a higher K-factor if an exact match is unavailable.
• Protect vessel ends with appropriate sprayer placement.

Spare Parts Supply Flow Diagram

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

IS 15325: Details on Annexes and Committee Composition

• Annex A: Lists referenced standards incorporated by reference. These standards' editions at time of publication are authoritative, though users should verify for newer versions.

  • Examples include fire safety codes and material standards.

• Annex B: Details the committee responsible for the standard’s preparation:

  • Fire Fighting Sectional Committee, CED 22
  • Composed of experts from government, industry, and academia specializing in fire safety.

• Clause 5.2.3: Covers general layout and design principles detailed in the main text.

Annex Summary Table

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