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IS 15505:2004 is the Indian Standard (BIS) for gaseous fire extinguishing systems - hcfc blend a extinguishing systems. This standard provides requirements for the design, installation, testing, and maintenance of gaseous fire extinguishing systems that use HCFC Blend A as the agent. It is intended for total flooding applications to protect enclosed hazards like data centers and control rooms where water-based suppression is undesirable. The code specifies agent concentration, quantity calculation, component requirements, and crucial safety guidelines for personnel.
Gaseous Fire Extinguishing Systems - HCFC Blend A Extinguishing Systems
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! HCFC Blend A is an ozone-depleting substance, and its production and use in new systems are phased out under the Montreal Protocol. This code is now primarily used for the maintenance and servicing of existing legacy systems.
! Room integrity is critical for the effectiveness of any gaseous suppression system. A door fan test as specified in Annex E is essential to ensure the enclosure can hold the agent concentration for the required duration.
! Strict safety protocols must be followed as discharge in an occupied space can pose a health risk, especially if the concentration exceeds the NOAEL of 10%.
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
HCFC Blend Agaseous extinguishantsteel
International Equivalents
Similar International Standards
NFPA 2001, 2022 EditionNational Fire Protection Association (NFPA), USA
HighCurrent
Standard on Clean Agent Fire Extinguishing Systems
Covers design, installation, and maintenance principles for all clean agents, including legacy data for HCFCs.
ISO 14520-12:2005International Organization for Standardization (ISO), International
HighWithdrawn
Gaseous fire-extinguishing systems — Physical properties and system design — Part 12: HCFC Blend A
Provided the direct international design and physical property requirements specifically for HCFC Blend A systems.
EN 15004-4:2008European Committee for Standardization (CEN), Europe
HighWithdrawn
Fixed firefighting systems - Gas extinguishing systems - Part 4: Physical properties and system design of gas extinguishing systems for HCFC Blend A extinguishant
Harmonized European standard based on ISO 14520-12, detailing requirements for HCFC Blend A systems.
Key Differences
≠The most significant difference is the regulatory context; IS 15505:2004 treats HCFC Blend A as a viable agent, whereas current international standards like NFPA 2001 and the withdrawn status of ISO 14520-12 reflect its phase-out under the Montreal Protocol, prohibiting its use in new systems in most developed countries.
≠NFPA and ISO standards place a heavy emphasis on third-party 'listing' and 'approval' (e.g., by UL, FM, VdS) for all system components. IS 15505 allows for conformance to Indian Standards or approval by the 'authority having jurisdiction,' which can be a different and potentially less stringent process.
≠IS 15505:2004 specifies a mandatory agent storage temperature range of 0°C to 50°C. International standards like NFPA 2001 typically defer to the manufacturer's listed temperature range for the specific system, which is often broader (e.g., -18°C to 54°C).
≠While general principles are similar, specific design limitations can vary. For example, IS 15505 provides a prescriptive maximum nozzle coverage area of 7.5 m x 7.5 m, whereas NFPA 2001 relies on the limitations established during the listing and approval testing of the specific nozzle model.
Key Similarities
≈All standards are fundamentally based on the 'total flooding' principle, requiring the calculation of an agent quantity to achieve a minimum design concentration throughout an enclosure's volume.
≈Human safety limits are nearly identical across the standards. They all use the concepts of NOAEL (No-Observed-Adverse-Effect-Level) and LOAEL (Lowest-Observed-Adverse-Effect-Level), specifying that design concentrations in normally occupied areas must remain below the NOAEL (10.0% for HCFC Blend A).
≈All standards mandate or strongly recommend conducting an enclosure integrity test (Door Fan Test) to verify that the protected room can hold the extinguishing concentration for the required time (typically 10 minutes).
≈The requirement for a maximum discharge time of 10 seconds for Class A (surface), Class C, and most Class B hazards is consistent across IS 15505, NFPA 2001, and the former ISO 14520-12.
≈All standards require the use of a verified hydraulic calculation software program to design the pipe network, ensuring correct agent distribution and flow rates within the specified discharge time.
Parameter Comparison
Parameter
IS Value
International
Source
Minimum Design Concentration (Class A, Surface Fire)
8.6%
8.61% (Derived from 6.62% extinguishing conc. + 30% safety factor)
ISO 14520-12:2005
Minimum Design Concentration (Class B, Heptane)
8.6%
8.6% (Derived from 6.6% extinguishing conc. + 30% safety factor)
NFPA 2001 (historical data)
Safety Limit for Occupied Spaces (NOAEL)
10.0%
10.0%
NFPA 2001 / ISO 14520-12
Maximum Discharge Time (Standard Hazards)
10 seconds
10 seconds
NFPA 2001
Minimum Agent Hold Time
10 minutes
10 minutes
NFPA 2001
Cylinder Test Pressure Requirement
As per Gas Cylinder Rules / IS 7285
Typically 5/3 times the normal charging pressure at 21°C
NFPA 2001
Pipe Material Specification
IS 1239 (Part 1) or IS 3589
ASTM A53/A106 Seamless or ERW, Schedule 40/80 as required
NFPA 2001
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Minimum design concentration for Class A surface fires8.0% by volume
Minimum design concentration for Class B fires (Heptane)8.7% by volume
No Observable Adverse Effect Level (NOAEL)10.0% by volume
Maximum discharge time for most hazards10 seconds
Storage cylinder pressure at 21°C25 bar
Minimum safety factor for agent calculation1.20 (20%)
Key Formulas
W = (V/s) * (C / (100 - C)) — Formula for calculating weight of extinguishing agent
Tables & Referenced Sections
Key Tables
Table 1 - Physical Properties of HCFC Blend A
Table 2 - Fire Extinguishing Concentrations for Heptane
Table 3 - HCFC Blend A Total Flooding Quantity
Table A.1 - Toxicological Information for HCFC Blend A
Key Clauses
Clause 4 - Characteristics and Use
Clause 5 - Safety
Clause 6 - System Design
Clause 7 - System Components
Clause 10 - Installation Requirements
Clause 12 - Inspection, Maintenance, Testing and Training
It is a gaseous fire extinguishing agent consisting of a blend of HCFC-123, HCFC-22, and HCFC-124, with a small amount of d-limonene added.
Is this system safe for occupied areas?+
It can be used in normally occupied areas only if the design concentration remains below the No Observable Adverse Effect Level (NOAEL) of 10.0% by volume, as per Clause 5.1.2.
What is the primary application of this system?+
Total flooding of enclosed spaces to protect against Class A, B, and C fires, particularly for high-value electronic equipment like servers and telecom switches.
Can I use this code for designing a new fire suppression system?+
No, it is not recommended for new installations due to the ozone-depleting nature of HCFCs. Refer to standards for modern clean agents like IS 15517 (HFC-227ea) or IS 16018 (FK-5-1-12).