Gaseous fire extinguishing systems - Physical properties and system design - CF3I extinguishant

Scope of IS 15821 for CF₃I (Trifluoroiodomethane) Fire Extinguishing Systems

• Application: CF₃I systems are suitable for extinguishing all fire classes within limits of IS 15493.
• Extinguishing Concentrations: Table 3 provides mass requirements per unit volume (kg/m³) for total flooding at various temperatures and design concentrations (3% to 10% by volume).

Key Specifications from IS 15821

Formula for Mass of CF₃I Required for Total Flooding

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

Where:

• (m) = mass of CF₃I (kg)
• (V) = volume of protected space (m³)
• (C) = design concentration (fraction by volume, e.g., 0.07 for 7%)
• (\rho) = density of CF₃I vapor at design temperature (kg/m³) — use Table 3 values

Example from Table 3 (at 20°C):

IS 15821 Key References for CF₃I Systems

1. Extinguishing & Design Concentrations (Table 5, Clause 4.2)

2. Inerting Concentrations (Table 6, Clause 4.2)

3. Total Flooding Quantity (Table 3, Clauses 4.1 & 6.3)

• Mass required per unit volume (kg/m³) depends on temperature and design concentration.
• Specific volume (S m³/kg) varies with temperature.
• Example at 25°C:

Use specific volume and temperature to interpolate values.

Notes:

• Data primarily sourced from ISO 14520-2.
• CF₃I systems cover all fire classes within IS 15493 limits.
• Design concentrations ensure effective extinguishment and safety margins.

flowchart TD
    A[Fuel Type] --> B[Extinguishment %]
    B --> C[Minimum Design %]
    C --> D[Calculate Mass Required]
    D --> E[Use Table 3 for Temperature Correction]
    E --> F[Determine Total Flooding Quantity]

For detailed design, refer to IS 15821 Clause 4 and ISO 14520-

IS 15821: Characteristics and Uses of CF₃I (Trifluoroiodomethane)

1. Physical Properties of CF₃I (Table 2, Clause 3.1)

2. Specifications (Table 1, Clause 3.1)

• Purity: ≥ 99.9% by mass
• Acidity: ≤ 1 × 10⁻⁶ by mass
• Water content: ≤ 6 × 10⁻⁶ by mass
• Non-volatile residue: ≤ 100 × 10⁻⁶ by mass
• Suspended matter: Non-visible

3. Extinguishing and Design Concentrations (Table 5 & 6, Clauses 3.9 & 4.2)

Key Specifications & Formulas for Use of CF₃I Systems (IS 15821):

1. Physical Properties of CF₃I (Trifluoroiodomethane) [Table 2]

2. CF₃I Purity Requirements [Table 1]

• Purity: ≥ 99.9% by mass
• Acidity: ≤ 1 × 10⁻⁶ by mass
• Water content: ≤ 6 × 10⁻⁶ by mass
• Non-volatile residue: ≤ 100 × 10⁻⁶ by mass
• Suspended matter: Non-visible

3. Extinguishing Concentrations & Mass Requirements [Table 3]

• Design concentrations range: 3% to 10% by volume
• Mass of CF₃I per unit volume (kg/m³) varies with temperature and concentration.

Example at 20°C:

Safety of Personnel in IS 15821 (Clause 5.2 & related)

• Toxicological Data for CF,I (Table 7):

  Property	Value (Percent)
  LC50 (15 min lethal conc.)	27.4
  ALC (4 hr lethal conc.)	>12.8
  NOAEL (No observed adverse effect level)	0.2
  LOAEL (Lowest observed adverse effect level)	0.4

• Key Notes:

  • LC50 = concentration lethal to 50% of rats in 15 min.
  • ALC = approximate lethal concentration for 4 hours.
  • Design concentrations include a 1.3 safety factor on extinguishing concentration (Clause 1.3).
  • Since design concentration > LOAEL, CF,I use is restricted to normally unoccupied spaces (Clause 5.3), e.g., rimseal fire protection in floating roof tanks.

• Design Concentration & Mass Requirements (Table 3):

  • Provides CF,I mass (kg/m³) needed at various temperatures and design concentrations (3% to 10% by volume).
  • Example at 25°C and 6% concentration: 0.5054 kg/m³.

Summary for Safety:

• Use CF,I only in unoccupied areas due to toxicity.
• Design concentration = extinguishing concentration × 1.3 safety factor.
• Refer Table 3 for exact mass requirements based on temperature and concentration.
• Follow minimum safety requirements per IS 15493 Clause 5.

flowchart LR
    A[Fire Hazard] --> B[Determine Extinguishing Concentration]
    B --> C[Apply Safety Factor 1.3]
    C --> D{Is Design Conc. > LOAEL?}
    D -- Yes --> E[Use CF,I only in Unoccupied Areas]
    D -- No --> F[Use CF,I in Occupied Areas]

This ensures personnel safety by limiting exposure to toxic CF,I concentrations.

IS 15821 – System Design for CF₃I Fire Extinguishing Systems

Key Points:

• CF₃I systems are suitable for extinguishing all fire classes within concentration limits per IS 15493.
• Used mainly in normally unoccupied areas due to toxicity concerns (Clause 5.3).

Important Tables & Formulas:

1. Total Flooding Quantity (kg/m³) vs Temperature & Concentration

(Table 3 excerpt for design concentration by volume)

Mass requirement = (Design Concentration %) / (Specific Volume)

2. Extinguishing & Minimum Design Concentrations (Table 4)

Note: Extinguishment values from ISO 14520-2.

Design Considerations:

• Use minimum design concentration for safety margin.
• Account for temperature effects on specific volume and mass requirements.
• Refer IS 15493 for minimum safety requirements and concentration limits in occupied spaces.

flowchart LR
    A[Determine Fire Class & Fuel] --> B[Select Design Concentration %]
    B --> C[Check Temperature & Specific Volume]
    C --> D[Calculate Mass Requirement (kg/m³)]
    D --> E[Design CF

IS 15821: Extinguishant Quantity for CF₃I Systems

Key Formula for Agent Mass (m):

[ m = c \times S \times V ]

• m = mass of agent (kg)
• c = design concentration (volume %)
• S = specific volume of CF₃I vapor (m³/kg)
• V = net hazard volume (m³)

Specific Volume (S) Approximation:

[ S = k_1 + k_2 \times T ]

• (k_1 = 0.1138), (k_2 = 0.0005)
• (T) = temperature in °C

Table 3: Mass Requirements (m/V) (kg/m³) at Various Temperatures and Concentrations

(Refer to full Table 3 for intermediate values)

Design Concentration Example (Table 4):

Summary:

• Calculate m using design concentration, specific volume (from temperature), and hazard volume.
• Use Table 3 for quick mass per volume values.
• Design concentration depends on fuel type (see Table 4).
• Ensure volume excludes fixed structures impervious to agent.

flowchart LR
    A[Determine Hazard Volume V]

IS 15821 - Quality Check: Key Points & Tables

Clause 4.3.4: Quality Check

• Ensures compliance with specified standards for fire extinguishing systems.
• Verification includes:
  • Correct extinguishant quantity (see Clause 2.5, Table 6.3).
  • Pressure and temperature checks (refer FIG. 2 for CF₃I pressurized to 2.5 MPa with nitrogen at 20℃).
  • Concentration levels per Clause 4.2 (Table 6).

Table 6: CF₃I Inerting and Design Concentrations (By Volume)

Note: Concentrations follow IS 15493 requirements.

Extinguishant Quantity (Clause 2.5, Table 6.3)

• Quantities depend on system volume and type.
• Must match design specs to ensure effective fire suppression.

Important Notes:

• Round off test results per IS 2:1960 rules.
• Ensure all parameters meet or exceed minimum design values.
• Use ISO 14520-2 data for compatibility with various fuels.

flowchart TD
    A[Start Quality Check] --> B[Verify Extinguishant Quantity]
    B --> C{Quantity OK?}
    C -- Yes --> D[Check Pressure & Temperature]
    C -- No --> E[Adjust Quantity]
    D --> F{Within Limits?}
    F -- Yes --> G[Check Concentration Levels]
    F -- No --> H[Adjust Pressure/Temperature]
    G --> I{Concentration OK?}
    I -- Yes --> J[Pass Quality Check]
    I -- No --> K[Adjust Concentration]

Summary:
Quality check per IS 15821 involves verifying extinguishant quantity, pressure, temperature, and concentration against specified tables and clauses to ensure system effectiveness and safety.

IS 15821: Discharge Time for CF₃I Systems

Key Points from Clause 4.3.3:

• Total flooding systems: Discharge time = 10 seconds.
• Local application systems: Discharge time depends on cylinder or glass bulb size.
• For 10 to 40 kg cylinders, discharge time ranges from 20 s to 45 s.

Relevant Formula for Agent Mass (Clause 1.021):

[ m = \frac{100 - c}{S_c} \times c \times V ]

Where:

• (m) = agent mass (kg)
• (c) = concentration (%)
• (S_c) = specific volume (m³/kg)
• (V) = protected volume (m³)

Specific Volume Approximation:

[ S = k_1 + k_2 \times T ]

• (k_1 = 0.1138) m³/kg
• (k_2 = 0.0005) m³/kg/°C
• (T) = temperature in °C

Table Extract: Mass Requirements per Unit Volume at 0°C (from Table 3)

Summary:

• Use 10 s discharge time for total flooding.
• For local application, select discharge time between 20-45 s based on cylinder size.
• Calculate agent mass using concentration, volume, and specific volume.
• Refer to Table 3 for design concentrations and mass requirements at different temperatures.

flowchart TD
    A[Determine Fire Type] --> B{System Type}
    B -->|Total Flooding| C[Discharge Time = 10s]
    B -->|Local Application| D[Discharge Time = 20-45s]
    D --> E[Select Cylinder Size (10-40 kg)]
    A --> F[Calculate Agent Mass]
    F --> G[Use m = ((100-c)/

IS 15821 - Super Pressurization Key Points

1. Physical Properties of CF₃I (Clause 3.1, Table 2)

2. Storage and Super Pressurization (Clause 6.1, Table 8)

• Note: Exceeding max fill density risks liquid full condition → rapid pressure rise with temperature → container integrity risk.

3. Pressure-Temperature Relation

• Refer to Fig. 1 (not provided) for pressure vs. temperature curves at different fill densities.
• Super pressurization = Pressure increase above vapor pressure due to temperature rise or fill density.

Summary Formula for Super Pressurization:

[ P_{super} = P_{container} - P_{vapour}(T) ]

Where:

• (P_{container}) = Container pressure at temperature T
• (P_{vapour}(T)) = Vapor pressure of CF₃I at temperature T

Practical Recommendations:

• Maintain fill density ≤ **1

IS 15821 - Fill Density Key Data (Clause 6.1):

• Maximum Fill Density:
  [ \boxed{1.680 \text{ kg/m}^3} ]

• Maximum Container Working Pressure at 50°C:
  [ \boxed{3.55 \text{ MPa}} ]

• Super Pressurization at 20°C:
  [ \boxed{1.0 \text{ MPa}} ]

Important Notes:

• Exceeding maximum fill density risks the container becoming liquid full, causing rapid pressure rise with temperature increases, potentially compromising container integrity.
• Refer to Fig. 2 (Pressure vs Temperature curves) for detailed pressure rise behavior at various fill densities.
• Table 8 summarizes container characteristics for CF₃I gas storage.

Practical Implication:

• Always ensure fill density ≤ 1.68 kg/m³ to maintain safe pressure limits.
• Design pressure must accommodate up to 3.55 MPa at 50°C.
• Consider super pressurization allowance of 1 MPa at 20°C.

graph LR
A[Fill Density ≤ 1.68 kg/m³] --> B[Safe Container Operation]
B --> C[Pressure ≤ 3.55 MPa @ 50°C]
B --> D[Super Pressurization ≤ 1 MPa @ 20°C]
A -.-> E[Exceeding Fill Density]
E -.-> F[Liquid Full Container]
F -.-> G[Rapid Pressure Rise]
G -.-> H[Risk of Container Failure]

For detailed fire extinguishing design, refer to IS 15493 and Table 3 of IS 15821 for CF₃I mass requirements per protected volume at various temperatures and concentrations.

Testing and Commissioning of CF₃I (Trifluoroiodomethane) Systems as per IS 15821

1. Gas Quality Testing:

• CF₃I purity must be ≥ 99.9% by mass (Table 1).
• Acidity ≤ 1×10⁻⁶ by mass.
• Water content ≤ 6×10⁻⁶ by mass.
• Non-volatile residue ≤ 100×10⁻⁶ by mass.
• No visible suspended matter.

2. Leak Testing:

• Use Nitrogen pressurized at 2.5 times the working pressure.
• Maintain pressure for 48 hours to verify leak tightness.

3. Post Leak Test Filling:

• Fill system with CF₃I.
• Pressurize to:
  • 1 MPa at 20°C
  • 1.2 MPa at 35°C

4. Pressure and Quality Monitoring:

• Pressure switch on cylinder signals control panel.
• Pressure gauge on cylinder for manual reading.
• Level switch on cylinder signals correct gas quality to control panel.

Key Physical Properties of CF₃I (Table 2)

Summary Diagram of Commissioning Process

flowchart TD
    A[Start: Installation Complete] --> B[Leak Test with N₂ at 2.5× Working Pressure]
    B --> C[Maintain Pressure for 48 Hours]
    C --> D{No Leak?}
    D -- Yes --> E[Fill with CF₃I Gas]
    E --> F[

Typical System Diagram - IS 15821 (Clause 4.3.2)

The Rim Seal Fire Protection System for floating roof tanks consists of:

• Container (CF₃I agent storage)
• Feed lines and ring mains/laterals
• Spray nozzles arranged around the rim seal
• Signalling equipment and cables
• Heat detection and activation devices
• Control panel with audio-visual indication

This system detects, controls, and extinguishes rim seal fires automatically.

Key Specifications & Tables:

1. Physical Properties of CF₃I (Table 2)

2. CF₃I Total Flooding Quantity (Table 3)

Mass of CF₃I required per m³ of protected space depends on temperature and design concentration:

Mass required (kg/m³) = Design Concentration (%) / Specific Volume (m³/kg)

Summary Diagram (Conceptual):

flowchart LR
    A[CF₃I Container] --> B[Feed Lines]
    B --> C[Ring Mains/Laterals]
    C --> D[Spray Nozzles]
    D --> E[Rim Seal Area]
    F[Heat Detectors] --> G[Control Panel]
    G --> H[Activation System]
    H --> B
    G --> I[Audio-Visual Alarm]

Note: CF₃I extinguishes fires

Application Limitations for CF₃I Systems (IS 15821)

1. Usage Scope (Clause 4.1):

• CF₃I systems are suitable for all fire classes within limits of IS 15493.
• Extinguishing mass per unit volume depends on design concentration (% by volume) and temperature.

2. Key Formula: Mass of CF₃I Required [ m = V \times \rho ] Where:

• ( m ) = mass of CF₃I (kg)
• ( V ) = volume of protected space (m³)
• ( \rho ) = mass requirement per unit volume (kg/m³) from Table 3 (varies with temperature & concentration)

3. Table 3 Snapshot: Mass Requirements (kg/m³) at 20°C

(Exact values vary slightly with temperature; see full Table 3.)

4. Safety & Application Limits (Clause 5.3):

• CF₃I concentration exceeds LOAEL (Lowest Observed Adverse Effect Level).
• Use only in normally unoccupied areas (e.g., rimseal fire protection, aircraft engine nacelles).
• Refer IS 15493 Clause 5 for minimum safety requirements.

5. Physical Properties (Table 2 Highlights):

• Molecular mass: 195.9
• Boiling point: -22.5°C
• Critical temperature: 122°C
• Vapour pressure at 20°C: 0.465 MPa
• Liquid density at 20°C: 2096 kg/m³

flowchart LR
    A[Fire Hazard] --> B{Use CF₃I?}
    B -- Yes --> C[Check Occupancy]
    C -- Unoccupied --> D[Calculate Mass Requirement]
    D --> E[Select Design Concentration]
    E --> F[Refer Table 3 for kg/m³]
    F --> G[Install & Maintain System]
    B -- No --> H[Use Other Fire Suppression]

Summary: Use CF₃I only in unoccupied spaces, calculate mass from

IS 15821: Safety and Compliance for CF₃I Fire Protection System

Key Specifications:

• CF₃I Purity: ≥ 99.9% by mass
• Acidity: ≤ 1 × 10⁻⁶ by mass
• Water Content: ≤ 6 × 10⁻⁶ by mass
• Non-volatile Residue: ≤ 100 × 10⁻⁶ by mass
• Physical Properties: Colourless, almost odourless, non-conductive gas, density ≈ 7× air

Toxicological Limits (Table 7)

• LC50: Lethal concentration for 50% rats in 15 mins
• ALC: Approximate lethal concentration in 4 hours

Design Concentrations & Mass Requirements (Table 3)

Mass required = Design Concentration (%) × Specific Volume (m³/kg)

Minimum Design Concentration for Propane (Table 6)

• Inertion: 6.5% by volume
• Minimum Design: 7.2% by volume

flowchart LR
    A[CF₃I Gas] --> B[Storage Container]
    B --> C[Multi Nozzle Sprayer]
    C --> D[Protected Space]
    D --> E[Fire Detection & Suppression]
    E --> F[Safety Monitoring (Toxicological Limits)]

Summary:
Use CF₃