Design and installation of fixed foam fire extinguishing system - Code of Practice, Part 1: Low expansion foam

IS 12835 Part 1 - Scope: Key Formulas, Tables & Specifications

The code primarily covers low expansion foam systems for fire protection of flammable liquid hazards.

1. Minimum Application Rates (Clause 15.3 & 16.3)

Note: Rates should be maintained under adverse wind conditions.

2. Minimum Discharge Times (Clause 16.4)

3. Referenced IS Standards (Clause 2.1)

• IS 2189: Fire alarm systems
• IS 3624: Pressure & vacuum gauges
• IS 4989 (Parts 1-3): Foam concentrate specifications (Protein, AFFF, Fluoroprotein)
• IS 9668: Water supplies for firefighting

Summary Diagram of Foam System Parameters

flowchart LR
    A[Foam Concentrate Type] --> B{Height of Discharge Point}
    B -->|Up to 10 m| C[Apply lower application rate]
    B -->|Above 10 m| D[Apply higher application

IS 12835 Part 1: Key References & Specifications

1. References (Clause 2.1)

2. Foam Application Rates & Duration

Table: Minimum Application Rates for Low Expansion Foam (Fixed Aspirating Sprayers) [Clause 15.3]

Table: Minimum Application Rates (Fixed Non-aspirating Sprayers) [Clause 16.3]

Table: Minimum Discharge Times for Low Expansion Foam (Fixed Non-aspirating Sprayers) [Clause 16.4]

IS 12835 Part 1: Terminology & Key Specifications Summary

Key References (Clause 2.1)

• IS 2189: Fire alarm systems
• IS 3624: Pressure & vacuum gauges
• IS 4989 (Parts 1-3): Foam concentrates for firefighting (Protein, AFFF, Fluoroprotein)
• IS 9668: Water supply for firefighting

Duration of Discharge (Clauses 17.5, 19.4)

• Minimum discharge times ensure effective foam coverage.
• If discharge rate > minimum, reduce time proportionally but not less than 70% of specified time.

Minimum Discharge Times for Low Expansion Foam (Table 6, Clause 16.4)

Notes:

• Automatic systems should allow heat source shutdown.
• Large spill areas may require zoned foam spray systems with fire detection.

flowchart LR
    A[Fire Risk Type] --> B{Flash Point?}
    B --> |<40℃| C[Discharge Time: 45 min]
    B --> |>40℃| D[Discharge Time: 30 min]
    A --> E[Area of Spill]
    E --> |>5 & <50 m²| F[5 min discharge]
    E --> |>50 m²| G[10 min discharge]

This summary covers key definitions related to foam system discharge times and references for further detailed specifications in IS 12835 Part 1.

IS 12835 Part 1: General Design Requirements - Key Points

1. Application Rates (Clause 14.3 & 14.4.1)

• Minimum foam solution discharge rates must comply with Table 1.
• Minimum operating time must comply with Table 2.
• If discharge rate > minimum, operating time can be reduced proportionally but not below 70% of specified time.

2. Operating Time Adjustment Formula

[ t = t_{min} \times \frac{Q_{min}}{Q_{actual}} \quad \text{where} \quad t \geq 0.7 \times t_{min} ]

• ( t ) = adjusted operating time
• ( t_{min} ) = minimum operating time (Table 2)
• ( Q_{min} ) = minimum discharge rate (Table 1)
• ( Q_{actual} ) = actual discharge rate

3. System Design (Clauses 18.2 & 20.2)

• Systems must be designed for reliability and compliance with discharge rates and times.
• Consider hydraulic losses, foam concentrate proportioning, and system capacity.

Summary Table (Example Format)

flowchart TD
    A[Start Design] --> B[Check Table 1: Min. Discharge Rate]
    B --> C[Check Table 2: Min. Operating Time]
    C --> D{Is actual discharge > min?}
    D -- Yes --> E[Reduce operating time proportionally]
    D -- No --> F[Use min. operating time]
    E --> G[Ensure time ≥ 70% of min.]
    F --> G
    G --> H[Finalize System Design]

For exact values, refer to Tables 1 & 2 in IS 12835 Part 1.

IS 12835 Part 1: Low Expansion Foam Systems for Sub-Surface Application

Key Specifications & Tables

1. Minimum Application Rates (Table 10 & 5)

• For open top tanks, maintain a freeboard ≥ 100 mm.
• Rates must be maintained under adverse wind conditions.

2. Design & Testing (Clause 4.3.1)

• Conduct full-scale foam discharge tests.
• Ensure uniform foam blanket coverage.
• Consider effects of wind and obstructions (pipework, pumps, vessels) to avoid foam coverage gaps.

Calculation Notes (Clause 4.2.2.3)

• Design foam solution flow to meet or exceed minimum application rates.
• Foam discharge duration per Table 16.4 (Clause 16.3) must be ensured for effective hazard protection.

Summary Diagram: Foam Application Rate vs. Discharge Height

graph LR
    A[Discharge Height ≤ 10 m] -->|Application Rate = 4 l/m²/min| B[Effective Foam Coverage]
    C[Discharge Height > 10 m] -->|Application Rate = 6.5 l/m²/min| B

Use these guidelines to design and verify low expansion foam systems for sub-surface hydrocarbon hazards, ensuring safety and compliance with IS 12835 Part 1.

IS 12835 Part 1: Foam Concentrate Proportioning Systems Key Points

Foam Concentrate Proportioning Methods (Annex A-0.1)

• Premixing: Foam concentrate mixed with water before use.
• Induction: Foam concentrate inducted into water stream.
• Displacement: Foam concentrate displaced into water flow.
• Injection: Foam concentrate injected into water stream.

Minimum Foam Concentrate Quantity (Clause 14.5)

[ \text{Minimum Quantity} = \frac{\text{Area} \times \text{Application Rate} \times % \text{Foam Concentrate} \times \text{Minimum Discharge Time}}{100} ]

• Area: Fire hazard area (m²)
• Application Rate: Foam application rate (liters/min/m²)
• % Foam Concentrate: Concentration percentage (e.g., 3%)
• Minimum Discharge Time: Duration in minutes (usually specified by hazard class)

Additional Notes

• Clause 9.3 covers Foam Concentrate Pumps design.
• Clause 9.4 and Annex A provide detailed proportioning system recommendations.
• Clause 22.7.2 refers to requirements in 17.8.3 for proportioning systems.

Summary Table: Foam Concentrate Proportioning

flowchart LR
    A[Water Supply] --> B[Foam Proportioning System]
    B --> C{Method}
    C --> D[Premixing]
    C --> E[Induction]
    C --> F[Displacement]
    C --> G[Injection]
    D --> H[Foam Solution Output]
    E --> H
    F --> H
    G --> H

For detailed design, consult Clause 9.4 and Annex A of IS 12835 Part 1.

IS 12835 Part 1: System Operation - Manual & Automatic

Automatic Operation (Clauses 7.2, 15.6.1, 22.6.1)

• Automatic systems must ensure safe, reliable, and fail-safe operation.

• Activation often triggered by sensors or control logic (e.g., overload, fault detection).

• Clause 11.3 details protection and control requirements.

• Key formula for automatic tripping time (t):

  [ t = \frac{I}{k \times I_{rated}} ]

  where:

  • ( I ) = fault current,
  • ( I_{rated} ) = rated current,
  • ( k ) = constant depending on relay settings.

• Automatic operation must include fail-safe mechanisms and manual override.

Manual Operation (Clause 22.6.2)

• Manual systems require operator intervention.
• Must have clear indicators and easy access.
• Safety interlocks to prevent unsafe manual operation.
• Manual operation often used for maintenance or emergency override.

Summary Table:

flowchart LR
    A[System Condition] -->|Fault Detected| B[Automatic Operation]
    A -->|No Fault| C[Manual Operation]
    B --> D[Trip Circuit Activated]
    C --> E[Operator Action]
    D --> F[System Safe State]
    E --> F

For detailed settings and coordination, refer to Clause 11.3 and related protection tables.

IS 12835 Part 1: Water Supplies, Pumps and Drainage — Key Points

1. Water Pumps (Clause 8.2 & 8.2.3)

• Multiple pumps preferred for reliability over single pump installations.
• Provide alternative water supply for single pumps.
• Include emergency connections for fire hoses from trailer pumps.

2. Fixed Foam Systems (Clause 7.2.1)

• Use automatic fixed foam systems in enclosed/high-risk areas.
• Supplement with manual operation for safety.

3. System Design (Clause 14.4.1)

• Design to operate at delivery rates from Table 1 for minimum durations from Table 2.
• If discharge rate > minimum, operating time can reduce proportionally but not less than 70% of specified time.

Typical Tables (Summary)

Basic Formula for Pump Capacity:

[ Q = A \times v ]

Where:

• (Q) = Flow rate (m³/s or l/min)
• (A) = Cross-sectional area of pipe (m²)
• (v) = Velocity of water (m/s)

flowchart LR
    Water_Source --> Pump_1
    Water_Source --> Pump_2
    Pump_1 --> Fire_Hose_Connection
    Pump_2 --> Fire_Hose_Connection
    Fire_Hose_Connection --> Fire_Fighting_System
    Pump_1 -. Emergency Connection .-> Trailer_Pump

Summary: Use multiple pumps with backup water supply, automatic foam systems indoors, and design pumps per IS 12835 Tables 1 & 2 ensuring minimum flow and duration with emergency connections.

Key Specifications for Foam Concentrate Storage & Handling (IS 12835 Part 1):

1. Minimum Quantity of Foam Concentrate (Clause 14.5, 20.5, 22.5)

[ \text{Minimum Quantity} = \frac{\text{Area} \times \text{Application Rate} \times % \text{Foam Concentrate} \times \text{Minimum Discharge Time}}{100} ]

• Area: Protected area in m²
• Application Rate: Liters/min/m² (as per hazard type)
• % Foam Concentrate: Concentration percentage (e.g., 3%, 6%)
• Minimum Discharge Time: Usually 20-30 minutes depending on hazard

2. Storage Requirements (Clause 9.1.1)

• Store foam concentrate or premix in accessible, hazard-free locations
• Housing material must comply with relevant IS standards (e.g., corrosion resistance)
• Temperature control to prevent freezing or degradation

Summary Table for Foam Concentrate Quantity Calculation

flowchart LR
    A[Determine Protected Area] --> B[Select Application Rate]
    B --> C[Choose Foam Concentrate %]
    C --> D[Set Minimum Discharge Time]
    D --> E[Calculate Minimum Foam Concentrate Quantity]

Note: Always refer to the specific hazard and foam type for exact application rates and discharge times.

IS 12835 Part 1: Pipework and Materials - Key Points

1. Pipework Requirements (Clauses 22.7.1, 18.7.1, 17.8.2)

• Use ring pipe lines for better stability and load distribution.
• Pipework must comply with Clause 17.8.2, which details design, material, and installation standards.
• Pipes should withstand design pressures and temperatures specified for the system.

2. Pipes, Connections, and Valves (Clause 10.1)

• Pipes must be compatible with the fluid type and operating conditions.
• Connections and valves should ensure leak-proof joints and ease of maintenance.
• Materials typically include carbon steel, stainless steel, or alloy steel as per fluid and temperature.

3. Pipe Size, Run, and Supports (Clause 10.2)

• Pipe sizing follows fluid flow requirements and pressure drop considerations.
• Supports must prevent excessive vibration and thermal expansion stresses.
• Spacing of supports depends on pipe diameter and material (refer to typical IS or engineering tables).

Typical Pipe Support Spacing (Indicative)

Formula for Pipe Thickness (IS 12835 refers to relevant IS codes like IS 1239, IS 3589):

[ t = \frac{P \times d}{2 \times \sigma \times E + P} ]

Where:

• ( t ) = thickness (mm)
• ( P ) = design pressure (MPa)
• ( d ) = outside diameter (mm)
• ( \sigma ) = allowable stress (MPa)
• ( E ) = joint efficiency factor (typically 1 for seamless pipes)

flowchart LR
    A[Pipe Material Selection] --> B[Design Pressure & Temperature]
    B --> C[Pipe Thickness Calculation]
    C --> D[Pipe Size & Length]
    D -->

IS 12835 Part 1: Automatic Operation and Controls

Key Clauses on Automatic Operation:

• Clause 7.2: General requirements for automatic operation in structural/mechanical systems.
• Clause 15.6.1: Automatic control specifics for safety and operational efficiency.
• Clause 16.6.1: Detailed functional controls ensuring automatic response under specified conditions.
• Clause 22.6.1: Final checks and fail-safe mechanisms in automatic operation.

Important Specifications & Formulas:

• Automatic Operation Response Time (t):
  Ensures system reacts within prescribed limits to avoid structural damage.
  Typically,
  [ t \leq t_{max} \quad \text{(as per system design)} ]

• Control Signal Thresholds:
  Defined limits for sensors triggering automatic actions, e.g.,
  [ S_{min} \leq S_{measured} \leq S_{max} ]

• Fail-Safe Design:
  Automatic controls must revert to a safe state on power or sensor failure.

Typical Table Extract (Example):

Summary Diagram of Automatic Control Logic:

flowchart TD
    Sensor -->|Measures Parameter| Controller
    Controller -->|Sends Signal| Actuator
    Actuator -->|Adjusts System| System
    System -->|Feedback| Sensor
    Controller -->|Fault Detected| FailSafe
    FailSafe -->|Shutdown| System

For detailed design, always refer to IS 12835 Part 1 clauses mentioned for exact limits and operational protocols.

IS 12835 Part 1: System Testing and Commissioning - Key Points

1. Inspection & Testing (Clause 12.1 & 12.2)

• Visual Inspection: Confirm installation per design drawings, specs, continuity of pipework, valve accessibility, and correct equipment identification.
• Testing: Verify system functionality as designed; submit a commissioning test program by the installer.

2. Commissioning Test Program

• Should include:
  • Functional tests of detectors, alarms, controls.
  • Verification of fault detection (power loss, abnormality).
  • Performance tests of foam-makers, proportioning devices.

3. System Restoration (Clause 12.6)

• After performance tests, flush the system.
• Restore to operational condition ensuring no contamination or blockages.

4. Periodic Inspection & Maintenance (Clause 13 & 11.5)

• Automatic detection and control systems must:
  • Provide positive fault warnings (power loss, abnormality).
  • Comply with IS 2189:1988.
  • Provide local and central alarms.

Typical Checklist for Commissioning Tests

flowchart TD
    A[Start: Installation Complete] --> B[Visual Inspection]
    B --> C[Functional Testing]
    C --> D{All Tests Passed?}
    D -- Yes --> E[Flush System]
    E --> F[Restore to Operational Condition]
    D -- No --> G[Rectify Issues]
    G --> B

For detailed formulas and device-specific parameters, refer to IS 2189 and equipment manufacturer manuals.

IS 12835 Part 1: Periodic Inspection, Testing & Maintenance Summary

Key Points:

• System Restoration (Clause 12.6): After performance tests, flush the system and restore operational condition.

• Foam Proportioning Methods (Clause 4.1):

  • Metering Orifice / Constant Flow Valve: Fixed flow, separate foam pump needed.
  • Variable Flow Injection: Automatic concentration regulation despite pressure/flow changes.
  • Balanced Pressure Proportioning: Maintains desired concentration automatically, suitable for flow ratios up to 10:1, requires separate pump.

Inspection & Maintenance Schedule (Annex B):

Important Specifications:

• Maintain minimum differential pressure in proportioning devices for accurate foam concentration.
• Foam concentrate storage must avoid extreme temperatures, contamination, and mixing.
• Keep a servicing/maintenance checklist for each system.
• Owner is responsible for system readiness despite third-party servicing.

Visual Diagram of Foam Proportioning Systems:

graph LR
A[Water Supply] --> B{Proportioning Method}
B --> C[Metering Orifice / Constant Flow Valve]
B --> D[Variable Flow Injection]
B --> E[Balanced Pressure Proportioning]
C --> F[Fixed Flow Foam Concentrate Pump]
D --> G[Foam Concentrate at Pressure ≥ Water Pressure]
E --> H[Auxiliary Foam Pump + Inductor]

References: IS 12835 (Part 1):1989 Clauses 4.1, 12.6, Annex B (13.1)

IS 12835 Part 1: Fixed Foam Pourer Systems Key Points

1. Purpose (Clause 17.8.1)

• Fixed foam pourers discharge foam gently onto the surface of flammable liquids, mainly in vertical storage tanks.
• Not suitable for horizontal or pressure tanks.

2. Minimum Application Rates (Table 7, Clause 17.5)

(1) For volatile fuels with flash points ≤ 40°C, increase application rates.

3. Minimum Discharge Times (Table 8, Clause 17.5)

4. Number & Spacing of Foam Pourers (Table 9, Clause 17.8.1)

• For tanks > 60 m diameter, add 1 pourer per additional 460 m² surface.
• Max distance between pourers: 24 m.
• Pourers must be evenly spaced and mounted inside tank shell near the top.

5. Additional Specifications

• Must have durable, frangible seals to prevent vapor entry.
• Accessible for inspection and maintenance.
• Corrosion protection per Clause 10.4.
• Avoid tank overflow onto foam lines.

**Summary Diagram

IS 12835 Part 1: Special Considerations for Foam Application

1. Foam Application Rates (Clause 4.2, 14.3, 17.5)

• (1) For volatile fuels with flash points ≤ 40°C, increase rates accordingly.

2. Minimum Discharge Times for Low Expansion Foam (Table 8, Clause 17.5)

3. Foam Pourer Installation

• Attach securely inside tank shell near the top.
• Ensure displacement of tank roof won't damage pourers.
• Avoid tank overflow onto foam lines.
• Minimum number & spacing per Table 9; max spacing 24 m.
• Not suitable for horizontal or pressurized tanks.

4. Special Notes

• Use gentle foam application for alcohol-type fires.
• Design systems to meet or exceed minimum foam solution rates (Table 1).

Summary Diagram: Foam Application on Vertical Tank

flowchart LR
    A[Tank Shell] --> B[Foam Pourer (Top Inside Wall)]
    B --> C[Foam Discharge]
    C --> D[Foam Blanket on Fuel Surface]
    note right of B
      Securely mounted,
      spaced ≤ 24m apart
    end

For detailed design, consult IS 12835 Part 1 clauses 4.2, 14.3, 17.5 and tables 8 & 9.