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IS 15821:2008 is the Indian Standard (BIS) for gaseous fire extinguishing systems - physical properties and system design - cf3i extinguishant. This standard specifies requirements for total flooding fire extinguishing systems using Iodotrifluoromethane (CF3I) as the extinguishing agent. It covers the agent's physical properties, system design criteria, safety precautions for personnel, installation procedures, and maintenance.
Gaseous fire extinguishing systems - Physical properties and system design - CF3I extinguishant
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! CF3I has a very low No-Observed-Adverse-Effect Level (NOAEL) of 0.2%, which severely restricts its application in normally occupied spaces.
! A mandatory Room Integrity Test is crucial to verify that the protected enclosure can hold the required agent concentration for the specified soaking time.
! CF3I is an environmentally acceptable Halon 1301 replacement (zero ODP) but is less commonly used than other clean agents like FK-5-1-12 or HFC-227ea due to its low toxicological safety margin.
gaseous fire extinguishantiodotrifluoromethaneCF3Iclean agent
International Equivalents
Similar International Standards
NFPA 2001:2022National Fire Protection Association (USA)
HighCurrent
Standard on Clean Agent Fire Extinguishing Systems
Provides design, installation, and maintenance requirements for various clean agents, including CF3I (Iodotrifluoromethane).
ISO 14520-1:2015International Organization for Standardization (International)
MediumCurrent
Gaseous fire-extinguishing systems — Physical properties and system design — Part 1: General requirements
Defines the general requirements for all gaseous systems, but the specific agent part for CF3I has been withdrawn.
ISO 14520-13:2005International Organization for Standardization (International)
HighWithdrawn
Gaseous fire-extinguishing systems — Physical properties and system design — Part 13: CF3I extinguishant
Was the direct international standard for CF3I systems, providing specific agent data; IS 15821 was based on this.
Key Differences
≠While IS 15821:2008 remains an active standard in India, the corresponding ISO standard (ISO 14520-13) has been withdrawn, and the agent's use is discouraged in Europe due to environmental concerns (Ozone Depletion Potential, though low).
≠IS 15821 specifies a No Observed Adverse Effect Level (NOAEL) of 0.2% for CF3I, which is more conservative than the 0.3% NOAEL listed in NFPA 2001. This impacts maximum allowable design concentrations in normally occupied spaces.
≠For Class C fires (electrically energized equipment), IS 15821 requires a minimum design concentration of 3.7% (same as Class A), whereas NFPA 2001 allows for a lower concentration of 3.2%.
≠Indian Standards are exclusively in SI units, whereas NFPA 2001 provides values and formulas in both US Customary and SI units, which can sometimes lead to minor rounding differences in calculations.
Key Similarities
≈All standards are based on the total flooding principle, requiring the calculation of agent mass needed to achieve a minimum design concentration in an enclosed volume for a specific hold time.
≈All standards mandate a maximum discharge time of 10 seconds for the system to release at least 95% of the agent mass for most applications.
≈Core safety requirements, such as the need for automatic/manual actuation, pre-discharge alarms with time delays for occupied areas, and manual override/abort switches, are consistent across all standards.
≈All standards require the use of a computer-based, listed, and approved hydraulic flow calculation program to design the pipework and nozzle distribution, prohibiting the use of simple pipe schedule methods.
Parameter Comparison
Parameter
IS Value
International
Source
No Observed Adverse Effect Level (NOAEL)
0.2% by volume
0.3% by volume
NFPA 2001:2022
Lowest Observed Adverse Effect Level (LOAEL)
0.4% by volume
0.4% by volume
NFPA 2001:2022
Min. Design Concentration (Class A, Surface)
3.7% by volume
3.7% by volume
NFPA 2001:2022
Min. Design Concentration (Class B, Heptane)
4.7% by volume (based on 3.6% extinguishing conc. x 1.3 safety factor)
4.7% by volume (based on 3.6% extinguishing conc. x 1.3 safety factor)
NFPA 2001:2022
Min. Design Concentration (Class C)
3.7% by volume
3.2% by volume
NFPA 2001:2022
Maximum Discharge Time
10 seconds
10 seconds
NFPA 2001:2022
Maximum Cylinder Fill Density
1600 kg/m³
1602 kg/m³ (100 lb/ft³)
NFPA 2001:2022
Agent Specific Volume (at 20°C)
0.121 m³/kg
0.124 m³/kg
ISO 14520-13:2005 (Withdrawn)
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
No-Observed-Adverse-Effect Level (NOAEL)0.2% by volume
Lowest-Observed-Adverse-Effect Level (LOAEL)0.4% by volume
Boiling Point at 1.013 bar-22.5 °C
Design Concentration for Class A Surface Fire3.2% by volume
Maximum Discharge Time10 seconds
Agent Storage Pressure (typical)25 bar at 21°C
Key Formulas
W = (V/s) * [c / (100 - c)] — Agent weight calculation, where V is volume, s is specific volume factor, and c is design concentration.
Tables & Referenced Sections
Key Tables
Table 1 - Physical Properties of Trifluoroiodomethane
Table 2 - Trifluoroiodomethane Total Flooding Quantities
Table A.1 - Extinguishing and Design Concentrations for n-Heptane
Table B.1 - Toxicological Information for Trifluoroiodomethane (CF3I)
Key Clauses
Clause 5 - Safety
Clause 6 - System Design
Clause 7 - Extinguishant Supply
Annex A - Determination of Extinguishing Concentrations
What is the NOAEL for CF3I and why is it important?+
The No-Observed-Adverse-Effect Level (NOAEL) is 0.2% by volume. It's the maximum concentration to which humans can be exposed without adverse effects, making it a critical safety limit for system design (Table B.1).
What is the maximum discharge time for a CF3I system?+
For most hazards, the system must discharge 95% of the required agent quantity within 10 seconds (Clause 6.6.3).
Can this agent be used in normally occupied spaces?+
Use in normally occupied spaces is highly restricted. The design concentration must remain below the very low NOAEL of 0.2%, which is often insufficient for fire suppression (Clause 5).
What is the typical design concentration for a Class A fire hazard?+
A minimum design concentration of 3.2% by volume is specified for Class A surface fire hazards (Table 2).