Gaseous Fire Extinguishing Systems - IG 541 Extinguishing Systems

IS 15501: Scope & Key Specifications Summary

Scope (Clause 1.4):

• Applies to gaseous fire extinguishing systems operating at nominal pressures of 15 MPa and 20 MPa at 15°C.
• References important standards:
  • IS 7285:1988 (Seamless steel cylinders for high-pressure gases)
  • IS 15493:2004 (Gaseous fire extinguishing systems - General requirements)

Key Formulas for IG 541 Gas Quantity (Clause 7.3.2)

Important Tables

1. Atmospheric Correction Factors (Table 12)

2. IG 541 Gas Specifications (Table 2)

3. Fire Extinguishing

Key References & Formulas from IS 15501 for IG 541 Gas Systems

1. IG 541 Agent Quantity Calculation (Clause 7.3.2)

• Theoretical quantity: [ M_{th} = V_{max} \times C_1 ]

  • (M_{th}): Theoretical IG 541 volume (m³)
  • (V_{max}): Max net enclosure volume (m³)
  • (C_1): Design injected concentration (volume %)

• Number of containers: [ N = \frac{M_{th}}{M_c} ]

  • (N): Number of containers
  • (M_c): IG 541 volume per container (m³)

• Actual quantity: [ M_A = N \times M_c ]

• Actual injected concentration: [ C_{AI} = \frac{M_A}{V_{max}} ]

2. Atmospheric Correction Factors (Table 12, Clause 7.3.3)

Use correction factor to adjust gas quantities for altitude.

3. Fire Extinguishing Oxygen Concentrations (Table 13, Clause 8.1(d))

Lower oxygen concentration means easier extinguishing.

4. **Physical Properties

IS 15501: General Information on IG 541 Gas

1. Gas Composition (Clause 4.2, Table 1)

2. Gas Specifications (Clause 4.4, Table 2)

3. Physical Properties of IG 541 (Clause 4.5, Table 3)

4. Key Formulas (Clause 7.3.2)

• Theoretical IG 541 quantity: [ M_{th} = V_{max} \times C_1 ] where (V_{max}) = max enclosure volume (m³), (C_1) = design concentration (vol %)

• Number of containers: [ N = \frac{M_{th}}{M_c} ] where (M_c) = agent quantity per container (m³)

• **Actual

IS 15501 — IG 541 Gas Characteristics & Specifications

1. Composition Range (Clause 4.2, Table 1)

2. Purity & Impurities Limits (Clause 4.4, Table 2)

3. Physical Properties (Clause 4.5, Table 3)

Summary

• IG 541 is a ternary gas mix: N₂, Ar, CO₂.
• High purity and strict moisture/oxygen limits ensure performance.
• Physical properties critical for storage and handling design.

flowchart LR
    A[IG 541 Gas] --> B[Composition]
    B --> C[Carbon dioxide 7.6-8.4%]
    B --> D[Argon 37.2-42.8%]
    B -->

Safety of Personnel - IS 15501 Key Points

1. IG 541 Gas Concentration & Safety Measures (Table 7)

*Above LOAEL not allowed in occupied areas.

2. Atmospheric Correction Factors (Table 12, Clause 7.3.3)

Adjust retention time based on altitude:

3. Fire Extinguishing Oxygen Concentrations (Table 13)

Minimum oxygen % to extinguish various gases (with Nitrogen dilutant):

4. Cylinder Pressure Limits (Clause 4.7)

IS 15501: Enclosure Strength & Venting Facilities

1. Enclosure Volumes (Clause 7.3.1)

• Maximum net volume: [ V_{Max} = V_a - V_3 ]

• Minimum net volume: [ V_{Min} = V_{Max} - V_o ]

Ignore (V_o) if < 25% of (V_{Max})

2. Venting Area Calculation (Clause 6.2)

[ A = (5 \times 10^{-4}) \times Q \times P^{-0.5} ]

• Note: For exceptionally tight enclosures, multiply (A) by 3.

3. Allowable Strength (P) (From Table 10, typical values)

Summary:

• Calculate net enclosure volume to size the system.
• Use discharge rate (Q) and enclosure strength (P) to find venting area (A).
• Provide venting at highest possible levels.
• Increase venting area for tight enclosures (multiply by 3).

flowchart TD
    A[Calculate Gross Volume \(V_a\)] --> B[Subtract Permanent Objects \(V

Key Formulas for Extinguishing Agent Supply (IG 541) - IS 15501

1. Total Flooding Quantity (kg):
   [ M = 2.303 \times V_s \times \log_{10} \frac{100}{100 - C} \times S \times V_3 ]

   • (M) = total flooding quantity (kg)
   • (C) = design concentration (% by volume)
   • (V_s) = net volume of hazard (m³)
   • (S = K_1 + K_2 \times T) (temperature-dependent constant)
   • (V_3) = specific volume at 21°C (m³/kg)
   • For IG 541: (K_1 = 0.658), (K_2 = 0.00239)

2. Theoretical IG 541 Quantity (m³):
   [ M_{th} = V_{max} \times C_{max} ]

3. Number of Containers:
   [ N = \frac{M_{th}}{M_c} ]

4. Actual Quantity Stored:
   [ M_A = N \times M_c ]

5. Actual Injected Concentration:
   [ C_{AI} = \frac{M_A}{V_{max}} ]

Important Tables

• Table 11: Mass requirements per unit volume (kg/m³) for IG 541 at various temperatures and concentrations.
• Table 8: Safety limits for IG 541 design concentration and residual gases.
• Table 12: Atmospheric correction factors based on altitude.
• Table 10: Allowable enclosure strength (kPa) for different construction types.

Notes

• Use the highest agent quantity from formula and Table 11 calculations.
• Adjust for leakage, ventilation, altitude using Table 12 correction factors.
• Ensure oxygen and CO₂ levels meet safety limits (Table 8).
• Reserve supply should be connected for uninterrupted protection.

flowchart TD
    A[Calculate Theoretical Quantity M_th] --> B[Determine Number of Containers N]
    B --> C[Calculate Actual Quantity M_A

IS 15501: Concentration Requirements for IG 541 Gas

Key Formulas

1. Total Flooding Quantity (kg):
   [ M = 2.303 \times V_s \times \log_{10} \left(\frac{100}{100 - C}\right) \times S \times V_3 ]

   • (M): total flooding quantity (kg)
   • (C): design concentration (% by volume)
   • (V_s): net volume of hazard (m³)
   • (S = K_1 + K_2 \times T) (temperature-dependent constant)
   • (V_3): specific volume at 21°C (m³/kg)
   • For IG 541: (K_1 = 0.658), (K_2 = 0.00239)

2. Theoretical IG 541 Quantity (m³):
   [ M_{th} = V_{max} \times C_1 ]

3. Number of Containers:
   [ N = \frac{M_{th}}{M_c} ]

4. Actual Quantity of Agent:
   [ M_A = N \times M_c ]

5. Actual Injected Concentration (%):
   [ C_{AI} = \frac{M_A}{V_{max}} \times 100 ]

Table 11: IG 541 Mass Requirements per Unit Volume (kg/m³)

IS 15501: Application Rate & Discharge Time Key Points

1. Application Rate (Clause 9.1)

• The rate of application is designed to achieve a residual CO2 concentration between 2.5% and 4.5% by volume in occupied enclosures (Clause 2.5).
• Nozzle selection and placement must ensure coverage less than the nozzle’s rated area (Clause 12.3).

2. Pipe Size and Maximum Flow Rate (Table 14, Clause 12.3)

3. Discharge Time

• Clause 10 requires that after 2 minutes from discharge start, the required CO2 concentration must be achieved.
• Retention time and atmospheric correction factors (Table 12) adjust for altitude and pressure effects on discharge.

4. Atmospheric Correction Factor (Table 12, Clause 7.3.3)

Protection of Occupants per IS 15501

Key Specifications:

• IG 541 total flooding systems must not exceed 52% design concentration (equivalent to 74% injected concentration) in normally occupied areas unless safe egress is ensured (Clause 5.1).
• Additional safeguards apply to prevent accidental human exposure (Clause 5.5).

Important Formulas (Clause 7.3.2):

Atmospheric Correction Factors (Table 12):

(Use factor to adjust agent quantity for altitude)

Fire Extinguishing Oxygen Concentration Limits (Table 13):

Safety:

• Oxygen and CO₂ levels after discharge must be within safe limits (see Fig. 2 and Table 8 in IS 15501).
• Post-discharge, ensure safe atmosphere within 2 minutes (Clause 10).

IS 15501: Key Formulas, Tables & Specs for IG 541 Storage Containers

1. Maximum Developed Pressure & Reference Temperature

• Filling pressure: 15 MPa at 15°C (Clause 5.4)
• Refer to Fig. 1 for temperature/pressure variation of IG 541 in containers.

2. IG 541 Quantity & Container Calculations (Clause 7.3.2)

3. Storage Container Pressure Specs

(Clause 4.7, Tables 5 & 6)

4. Mass Requirements per Unit Volume (Table 11 Excerpt)

(Use full Table 11 for detailed design)

5. Safety & Standards

• Comply with IS 15493 (Gaseous Fire Extinguishing Systems)
• Cylinders per IS 7285 (Seamless Steel Cylinders for High Pressure Gases)

flowchart TD
    A[Calculate Vmax] --> B[Determine Theoretical Quantity Mth]
    B --> C[Calculate Number

IS 15501: Distribution System & Pipe Sizing (Clause 12.3)

Key points:

• Pipe sizing balances pressure loss and flow velocity.
• Too small bore → excessive pressure drop.
• Too large bore → low velocity, possible lower flow rates.

Pipe Size Chart (Table 14)

Design Specifications:

• Pipes must withstand max pressure at max storage temp (Clause 12.1).
• Typical pressure ratings:
  • 15 MPa system → 22.5 MPa at 55°C
  • 20 MPa system → 30 MPa at 55°C (Clause 22.5)
• Material & corrosion protection:
  • Carbon steel: galvanized inside/outside or protected
  • Stainless steel: corrosion protection not mandatory

General Formula for Pressure Drop (Darcy-Weisbach):

[ \Delta P = f \frac{L}{D} \frac{\rho v^2}{2} ]

Where:

• ( \Delta P ) = pressure loss (Pa)
• ( f ) = friction factor
• ( L

IS 15501: Hydraulics of the System - Key Formulas, Tables & Specs

1. Hydraulic Calculation Requirements (Clause 13.1)

• Use approved methods to predict:
  • Pipe sizes
  • Nozzle pressure
  • Agent flow rate
  • Discharge per nozzle
  • Discharge time

2. Pipe Size & Maximum Flow Rate (Clause 12.3, Table 14)

3. Pressure & Material Specifications (Clause 22.5)

• System pressures at 55°C:
  • 15 MPa system: 22.5 MPa max
  • 20 MPa system: 30 MPa max
• Piping must withstand max pressure per IS 15493.
• Materials:
  • Carbon steel pipes: galvanized inside/outside or corrosion-protected
  • Stainless steel pipes: corrosion protection not mandatory

4. General Notes

• Nozzle placement must ensure coverage area < nozzle coverage rating.
• Pipe sizing balances pressure loss and flow velocity.
• Use approved software or hydraulic

IS 15501: Commissioning and Acceptance Testing - Key Points

1. Commissioning Certification (Clause 14.2)

• Installation agency issues a test certificate after system commissioning completion.

2. Accuracy Limits (Clause 13.2)

• Agent weight discharged: Actual vs predicted within -5% to +10%.
• Discharge time: Actual vs predicted within ±5 seconds.
• Nozzle pressures: Actual pressures must be within acceptable range for nozzle performance.

3. Acceptance Criteria (Clause 14.1)

• Commission per IS 15493.
• Performance proof by:
  • Full-scale discharge test (if required by authorities).
  • Otherwise, follow alternative approved procedures.

4. Atmospheric Correction Factors (Table 12, Clause 7.3.3)

(Use factor to adjust agent concentration for altitude)

5. Fire Extinguishing Concentrations (Table 13, Clause 8.1(d))

Summary Diagram: Commissioning Process Flow

flowchart TD
    A[System Installation] --> B[Commissioning per IS 15493]
    B --> C{Full-scale discharge

IS 15501: Full Scale Discharge Test Procedure (IG 541 System)

Key Points & Tables:

1. Test Preconditions (Clause 14.3):

   • If system fails compliance, faults must be rectified and retested.

2. Atmospheric Correction Factor (Table 12, Clause 7.3.3):
   Corrects gas concentration for altitude and pressure differences.

3. Fire Extinguishing Concentrations (Table 13, Clause 8.1(d)):
   Oxygen concentration limits for various gases with nitrogen or CO₂ dilutants.

4. Pipe Size & Max Flow Rate (Table 14, Clause 12.3):
   Select pipe size based on flow rate and run length.

5. Post Discharge (Clause 10):
   • After 2 minutes of discharge, conditions must meet specified criteria (e.g., extinguishing concentration).

Summary of Full Scale Discharge Test Steps:

• Verify system installation