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IS 15835:2009 is the Indian Standard (BIS) for gaseous fire extinguishing systems - hcfc-125 extinguishing systems. This standard provides requirements for the design, installation, functioning, maintenance, and testing of gaseous fire extinguishing systems using HCFC-125 as the extinguishant. It is intended for total flooding systems protecting enclosed hazards, focusing on agent concentration, safety for personnel, and system integrity.
Gaseous Fire Extinguishing Systems - HCFC-125 Extinguishing Systems
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Room integrity is critical. A Door Fan Test as per Annex E is mandatory to ensure the enclosure can hold the required gas concentration for at least 10 minutes.
! HCFC-125 is an ozone-depleting substance with high global warming potential, and its use is being phased down under international agreements. Consider modern alternatives like inert gases (IG-55, IG-100) or chemical agents with lower environmental impact (e.g., FK-5-1-12).
! For normally occupied areas, the design concentration must not exceed the NOAEL of 7.5%. If it does, strict safety measures including lock-out valves and time delays are mandatory.
ISO 14520-9:2019International Organization for Standardization (ISO), International
HighCurrent
Gaseous fire-extinguishing systems — Physical properties and system design — Part 9: HFC 227ea extinguishant
IS 15835 is a direct adoption of an earlier version of this ISO standard, covering HFC 227ea system design and properties.
NFPA 2001, 2022 EditionNational Fire Protection Association (NFPA), USA
HighCurrent
Standard on Clean Agent Fire Extinguishing Systems
Both standards provide comprehensive requirements for designing, installing, and maintaining HFC 227ea total flooding systems.
EN 15004-5:2017European Committee for Standardization (CEN), Europe
HighCurrent
Fixed firefighting systems - Gas extinguishing systems - Part 5: Design, installation and maintenance (for HFC 227ea)
This European standard, based on ISO 14520, sets rules for HFC 227ea systems, aligning closely with the scope of IS 15835.
Key Differences
≠IS 15835:2009 is based on an older (c. 2006) version of ISO 14520-9 and has not been updated, whereas international standards like NFPA 2001 and ISO 14520 have been revised multiple times to include new research and safety data.
≠IS 15835 specifies compliance with Indian Standards for components (e.g., cylinders under IS 7285, pipes) and approval by Indian regulatory bodies like BIS, while international standards reference their respective component standards (ASTM, EN) and listing bodies (UL, FM Global, VdS).
≠While fundamental safety levels (NOAEL/LOAEL) are the same, recent editions of NFPA 2001 provide more advanced safety evaluation methods, such as Physiologically-Based Pharmacokinetic (PBPK) models for assessing egress time from spaces with concentrations above the NOAEL.
≠IS 15835 prescribes a maximum nozzle height of 6 meters, whereas NFPA 2001 allows for greater nozzle heights provided the specific nozzle has been tested and listed for such applications, offering more design flexibility.
Key Similarities
≈All standards are based on the total flooding principle, calculating the required agent mass to achieve a minimum design concentration throughout the protected volume.
≈The standards mandate a maximum discharge time of 10 seconds to achieve 95% of the design concentration for most hazards, ensuring rapid extinguishment.
≈All standards utilize the same fundamental safety thresholds for HFC 227ea: a NOAEL of 9.0% and a LOAEL of 10.5% for cardiac sensitization, guiding safe design in occupied areas.
≈Enclosure integrity testing via a door fan test is a mandatory requirement in all standards to verify that the protected space can retain the agent concentration for a minimum specified time, typically 10 minutes.
≈The core extinguishing and design concentrations for various hazard classes (e.g., Class A, Class B) and the application of safety factors are fundamentally aligned across the standards.
Parameter Comparison
Parameter
IS Value
International
Source
Agent Name Note
IS 15835 covers HFC 227ea (Heptafluoropropane)
NFPA 2001 covers multiple agents, including HFC 227ea
What is the minimum design concentration for a server room fire?+
8.0% for Class A (surface fire) hazards, as specified in Table 2.
Can HCFC-125 systems be used in occupied spaces?+
Yes, but only if the design concentration is below the NOAEL of 7.5%. For concentrations above this, the area must be evacuated before discharge (Clause 5.1.2).
How long does the gas need to be held in the room after discharge?+
A minimum of 10 minutes, or a time sufficient for emergency response personnel to arrive, to prevent re-ignition (Clause 6.8.2).
What is a room integrity test and is it required?+
It is a test using a 'door fan' to measure an enclosure's leakage rate to ensure it can hold the gas concentration. It is a mandatory part of commissioning as per Annex E.