A debate is circulating the industry as to why certain gas suppression suppliers use NFPA gas design concentrations in favour of the gas design concentrations in the local SANS / ISO standards which are referenced in SANS 10400:T 2020.
The NFPA 2001- the American based standard for clean agent fire suppression systems requires less gas than the recommended SANS /ISO 14520 equivalent. The overall system would then appear more cost effective to the end user.
What are the overall implications?
In Annexure C of the ISO 14520 standard, the igniter for the plastic sheet test is twice the size of the one used in the UL tests (conducted for NFPA standards), ultimately resulting in a far more intense fire by the time you introduce the agent.
The ISO 14520 standard requires that you knock down the main fire within 60 seconds and completely extinguish any remaining (candle) flames within 3 minutes. The UL / FM test permits 10 minutes to fully extinguish.
In ISO 14520, a 30% safety factor is added to the extinguishing concentration to achieve to the design concentration, whereas in the NFPA 2001 standard, a 20% safety margin is incorporated.
In Europe, Australasia, and South Africa we use the ISO 14520 design concentrations.
This is specified in the application of the building regulations SANS 10400 Part T:2020 - 4.36.1 and Annexure C.
Should one wish to use NFPA design concentrations in South Africa this will fall into the category of a rational design which must be conducted by an ECSA registered engineer. If this is not done the design is not in compliance with the National Building Regulations.
Check what you are being offered before accepting the cheapest quote!
Lets keep this an even playing field - gas designs in South Africa should comply with SANS / ISO 14520.
By Keith Norgate – FSIB Fire Systems
If there are any topics you wish highlighted contact us on the following
Email: