Gaseous Fire Extinguishing Systems - IG 100 Extinguishing Systems

IS 15525: Scope - Key Formulas, Tables, and Specifications

1. Enclosure Volume Calculations (Clause 7.3.1)

• Maximum net volume:
  [ V_{Max} = V_a - V_{s} ]
• Minimum net volume:
  [ V_{Min} = V_{Max} - V_{o} ] where:
  • (V_a) = Gross enclosure volume (m³)
  • (V_s) = Volume of permanent objects impermeable to gas (m³)
  • (V_o) = Volume of occupancy-related objects impermeable to gas (m³) (ignored if < 25% of (V_{Max}))

2. IG 100 Design Concentration Safety Limits (Clause 5.4, Table 6)

3. Safety Precautions Based on IG 100 Concentration (Clause 5.4, Table 5)

4. IG 100 Agent Exposure Limits (Clause 5.5, Table 7)

IS 15525 Key Formulas, Tables & Specifications - General Information

1. Safety Concentration & Exposure Limits (Clause 5.4, 5.5)

• NOAEL: 43% IG 100, Oxygen ≥ 12%
• LOAEL: 52% IG 100, Oxygen ≥ 10%

2. Enclosure Strength (Clause 6.2)

3. IG 100 Agent Specifications (Clause 4.4)

4. Discharge Time (Clause 9.2)

• 95% agent mass discharged within 60 seconds at 27°C.
• Minimum theoretical concentration (34% vol) reached within 1 minute.
• Actual concentration (with safety factor) within 2 minutes.

IS 15525: Key Formulas, Tables & Specifications for Application

1. Rate of Application (Clause 9.1)

• Minimum theoretical injected concentration = 34% by volume
• Achieve within 1 minute
• Actual injected concentration (with safety factor) within 2 minutes
• 95% of agent mass discharged within 60 seconds

2. Safety Precautions (Clause 5.4)

• NOAEL = 43%, LOAEL = 52% (Design Concentration)

3. Human Exposure Limits (Clause 5.5)

4. Allowable Enclosure Strength (Clause 6.2)

5. Total Flooding Quantity (Clause 7.2(b), Table 9)

IS 15525: IG 100 Gas (Nitrogen) Properties & Specifications

Table 1: Physical Properties of IG 100 (Clause 4.2)

Table 2: IG 100 Gas Specification (Clause 4.4)

Notes:

• IG 100 is pure nitrogen used as an inert gas in fire suppression.
• Purity and low moisture content are critical to ensure gas performance and safety.
• Critical pressure and temperature define the gas phase behavior important for storage and discharge design.

flowchart TD
    A[IG 100 Gas (Nitrogen)] --> B[Physical Properties]
    A --> C[Specifications]
    B --> D[Molecular Mass: 28.02]
    B --> E[Boiling Point: -195.8°C]
    B --> F[Critical Pressure: 33.99 MPa]
    C --> G[Purity ≥ 99.6%]
    C --> H[Moisture ≤ 50 ppm]
    C --> I[Oxygen ≤ 0.1%]

This concise summary covers essential IG 100 gas data per IS 15525 for design and compliance.

IS 15525: Safety of Personnel - Key Formulas, Tables, and Specifications

1. Toxicological Limits for IG 100 (Table 3 & 6)

2. Safety Precautions Based on IG 100 Concentration (Table 5)

3. Human Exposure Limits (Table 7)

4. Allowable Enclosure Strength (Table 8)

5. Fill Pressure for IG 100 Cylinders (Clause 4.6 & Table 4)

• **15 MPa

IS 15525: Enclosure Strength and Venting Facilities

1. Allowable Enclosure Strength (Table 8, Clause 6.2)

For exceptionally tight enclosures, P is trebled.

2. Venting Area Calculation (Clause 6.2)

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

• A = free venting area (m²)
• Q = IG-100 agent discharge rate (m³/min)
• P = allowable enclosure strength (kPa)

3. Safety Limits & Exposure (Tables 5, 6, 7)

• Design Concentrations (% by volume):

  • NOAEL (No Observed Adverse Effect Level): 43% IG-100, 12% O₂
  • LOAEL (Lowest Observed Adverse Effect Level): 52% IG-100, 10% O₂

• Human Exposure Limits:

  IG-100 %	O₂ %	Exposure Time	Space Status
  ≤43	12	≤5 min	Normally occupied
  43-52	10-12	≤3 min	Normally occupied
  52-62	8-10	≤30 s	Normally occupied
  >62	<8	No exposure	Normally unoccupied

• Safety Precautions:

  • Below NOAEL (<43%): Inhibit switch & time delay required
  • Between NOAEL & LOAEL (43-52%): Inhibit switch, egress ≤30s, safety interlock required
  • Above LOAEL (>52%): Inhibit switch only

flowchart TD
    A[IG

IS 15525: Concentration Requirements for IG 100 (Inert Gas) Fire Suppression

Key Formulas (Clause 7.3.2)

1. Theoretical IG 100 Quantity:

[ M_{th} = V_{max} \times C_1 ]

• (M_{th}) = theoretical IG 100 volume (m³)
• (V_{max}) = maximum net volume of enclosure (m³)
• (C_1) = design injected concentration (volume fraction)

2. Number of Containers:

[ N = \frac{M_{th}}{M_c} ]

• (N) = number of containers
• (M_c) = IG 100 volume per container (m³)

3. Actual IG 100 Quantity:

[ M_A = N \times M_c ]

• (M_A) = actual IG 100 volume stored (m³)

4. Actual Injected Concentration:

[ C_{AL} = \frac{M_A}{V_{max}} ]

• (C_{AL}) = actual injected concentration (volume fraction)

Discharge Duration (Clause 9.2)

• Minimum design concentration (34% by volume) must be reached within 1 minute.
• Actual injected concentration (with safety factor) within 2 minutes.
• 95% of agent discharged within 60 seconds.

Total Flooding Quantity Table (Clause 7.2 & Table 9)

IS 15525 Key Formulas & Tables for Calculation of IG 100 Agent Quantity

1. Total Flooding Quantity (Clause 4.303 & 7.2a)

[ M = \frac{4.303 \times V_s \times 100 \times 10 \times (100 - C)}{V \times S \times 100} ]

Where:

• M = Total flooding quantity (kg)
• C = Design concentration (% by volume)
• V = Net hazard volume (m³)
• V_s = Volume of structural/permanent objects impermeable to gas (m³)
• S = (K_1 + K_2 \times T) (temperature-dependent constant)
• K₁ = 0.79968, K₂ = 0.00294 for IG 100
• T = Minimum enclosure temperature (°C)

2. Agent Quantity per Unit Volume (Table 9.2)

• Provides mass requirements (kg/m³) for IG 100 at various temperatures and design concentrations (34%-62% vol).
• Use specific vapor volume S from table for temperature.
• Select highest agent quantity from formula and table.

3. IG 100 Parameters (Clause 7.3.2)

• (V_{max}) = Max net volume (m³)
• (C_1) = Injected concentration
• (M_c) = Agent quantity per container (m³)

4. Discharge Duration (Clause 9.2)

• 95% agent mass discharged within 60 seconds at 27°C.
• Minimum theoretical concentration (34%) achieved within 1 minute.
• Actual concentration (including safety factor) within 2 minutes.

IS 15525: Key Points on Discharge Time & Retention Time for IG 100

Discharge Time (Clause 9.2)

• Definition: Time to discharge 95% of agent mass at 27°C to reach minimum design concentration + 20% safety factor.
• Minimum Concentration: 34% by volume must be reached within 1 minute.
• Actual Concentration: Achieved within 2 minutes.
• 95% Agent Release: Within 60 seconds.
• Flow Calculations: Per Clause 12 or pre-engineered system specs.
• Extended Discharge: Allowed at reduced rate after initial discharge, must be tested.
• Remote Containers: Transit time affects discharge; consult authorities.

Retention Time (Clause 9.3)

• After discharge, at least 80% of design concentration must remain for 10 minutes.

Table: Total Flooding Quantity of IG 100 (Excerpt)

Atmospheric Correction Factors (Table 10)

Summary Diagram: Discharge & Retention Time Flow

flowchart TD
    A[Start Discharge] --> B[Reach 34% Concentration in 1 min]
    B --> C[95% Agent Released in 60 s]
    C --> D[Complete Discharge within 2 min]
    D --> E[Maintain ≥80% Concentration for 10 min]

Note: Use Table 9.2 for precise agent mass based on temperature and design concentration. Ensure compliance with enclosure strength and safety measures per IS 15525

IS 15525: Key Formulas, Tables & Specs for IG 100 Storage Containers

1. Storage Container Requirements (Clause 10)

• Seamless cylinders per IS 7285, certified by Chief Controller of Explosives.
• Design pressure: max pressure at 55℃ or max controlled temp.
• Must have reliable pressure indicators and pressure-temperature charts.
• Authority specs may override IS 15525 if more stringent.

2. Key Formulas for IG 100 Quantity & Containers (Clause 7.3.2)

3. Table: Atmospheric Correction Factors (Clause 7.4.3)

Use to adjust agent dosing for altitude.

4. Table: Fill Pressure of IG 100 Containers (Clause 4.6)

5. Retention Time (Clause 9.3)

• After discharge, ≥80% of design concentration must remain after 10 minutes.

Summary Diagram of Storage

IS 15525: Distribution System Key Points

1. Discharge Duration (Clause 9.2)

• 95% agent mass discharged within 60 s at 27°C.
• Minimum theoretical injected concentration: 34% by volume within 1 min.
• Actual injected concentration (with safety factor) achieved within 2 min.
• Flow calculations per IS 15493 or pre-engineered system data.

2. Retention Time (Clause 9.3)

• After discharge, at least 80% of design concentration must remain after 10 minutes.

3. Total Flooding Quantity (Table 9)

• Mass of IG 100 agent per unit volume depends on temperature and design concentration.
• Example at 25°C, 34% concentration: 0.409 kg/m³.
• Use specific vapor volume and correction factors for altitude.

4. Atmospheric Correction Factors (Table 10)

Use correction factor to adjust agent quantity for altitude.

5. Enclosure Strength (Table 8)

6. Safety Limits (Tables 5, 6, 7)

• NOAEL: 43% IG 100, Oxygen 12% (safe exposure ≤ 5 min).
• LOAEL: 52% IG 100, Oxygen 10% (exposure ≤ 3 min).
• Above LOAEL (>52%) requires strict safety interlocks.

Formula for Agent Mass (m):

[ m = V \times C \times \rho ]

• ( V ) = Enclosure volume (m³)
• ( C ) = Design concentration (volume % / 100)

IS 15525 — Hydraulics of IG-100 System: Key Formulas & Tables

1. Hydraulic Calculation Essentials (Clause 12.1 & 11.3)

• Use an approved hydraulic method or software to calculate:

  • Pipe sizes (optimize bore to balance pressure loss & velocity)
  • Nozzle pressure & flow rate
  • Discharge per nozzle
  • Discharge time (usually 60 s for 95% agent release)

• Pipe sizing must prevent excessive pressure drop but maintain flow velocity for effective discharge.

2. Pressure Ratings & Piping (Clause 13.5)

• Systems designed for:
  • 20 MPa at 55°C (for 13.5 MPa systems)
  • 25 MPa at 55°C (for 16.2 MPa systems)
• Piping must comply with IS 15493 and withstand max pressure at 55°C.
• Carbon steel pipes: galvanized inside/outside or corrosion-protected.
• Stainless steel pipes: corrosion protection optional.

3. Discharge Duration (Clause 9.2)

• Discharge time to release 95% agent mass within 60 s at 27°C.
• Minimum injected concentration: 34% by volume within 1 min.
• Actual concentration includes safety factors, achieved within 2 min.

4. Agent Quantity Table (Clause 7.2(b), Table 9)

• Mass of IG-100 agent per unit volume depends on temperature & design concentration.

Refer to the full table for detailed values at other temperatures and concentrations.

5. Basic Formula for Agent Mass:

[ m = V \times \rho = \frac{V}{v_s} ]

Where:

• ( m ) = mass of agent (kg)
• ( V ) = volume

IS 15525: Commissioning and Acceptance Testing Key Points

1. Commissioning Certification (Clause 13.2)

• Installation agency must issue a test certificate after system commissioning.

2. Accuracy Limits (Clause 9.1)

• Agent weight discharged per nozzle: within -5% to +10% of predicted.
• Discharge time: ±5 seconds of predicted.
• Nozzle pressure accuracy: must be within the range for acceptable nozzle performance.
• Nozzle pressure must not fall below minimum or exceed maximum for uniform agent distribution.

3. Acceptance Criteria (Clause 13.1)

• Commissioning per IS 15493.
• Full-scale discharge test is not normally recommended.
• If insisted, conduct as per Clause 14.
• Otherwise, follow procedural checks without full discharge.

4. Reporting Requirements (Clause 14.3)

Summary Table: Accuracy Limits

flowchart TD
    A[System Commissioning] --> B[Test Certificate Issued]
    B --> C[Check Accuracy Limits]
    C -->|Within Limits| D[Acceptance]
    C -->|Out of Limits| E[Rectify & Retest]
    D --> F[Prepare Report as per Clause 14.3]

This ensures system reliability and compliance with IS 15525 and IS 15493 standards.

IS 15525: Full Scale Discharge Test Procedure for IG 100 System

Key Points from Clause 14 (Full Scale Discharge Test Procedure):

• Discharge Time Requirements (Clause 9.2):

  • 95% agent mass discharged within 60 seconds at 27°C.
  • Minimum theoretical injected concentration: 34% by volume within 1 minute.
  • Actual injected concentration (with safety factor) achieved within 2 minutes.
  • Flow calculations per Clause 12 or approved pre-engineered systems must demonstrate compliance.

• Total Flooding Quantity (Clause 7.2(b), Table 9):

  • Mass of IG 100 agent per unit volume depends on temperature and design concentration.
  • Example values at 27°C (approximate):

• Reporting Requirements (Clause 14.3):
  • System identification: installer, designer, enclosure ID, temperature, residual gases.
  • Date/time of test, discharge time.
  • Concentration levels at 2 and 10 minutes.
  • Any system deficiencies.
  • Reference to IS 15493.

Summary Formula for Agent Quantity:

[ \text{Agent mass (kg)} = \text{Enclosure volume (m}^3) \times \text{Mass requirement (kg/m}^3) ]

where mass requirement is taken from Table 9 based on temperature and concentration.

flowchart TD
    A[Start Full Scale Discharge Test] --> B[Measure Enclosure Temp & Volume]
    B --> C[Calculate Agent Mass using Table 9]
    C --> D[Discharge IG 100 Agent]
    D --> E{Discharge Time ≤ 60s?}
    E -- Yes --> F[Measure Concentration at 2 & 10 min]
    E -- No --> G[Rectify Fault and Retest]
    F --> H[Report Test Results per Clause 14.3]
    G --> D

Note: Full scale discharge test is generally not recommended unless