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
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
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%.