- Details
- Written by: Keith Norgate
- Category: Gas Extinguishing
- Hits: 256
BEWARE!!!
Recently there have been reports of quartzoid bulb operated gas modules being installed in different environments.
Some of them are filled with HFC227 and others with HFC236fa or NAF S227.
Why are we concerned?
1. This type of installation does not comply with any South African standard.
2. We cannot find any approvals on these systems and cylinders.
We can find no tests by any third party authority.
3. HFC227 is a flooding agent and reduces temperature in a closed environment to kill the fire.
HFC 236 is a streaming agent that is not listed in the national standard SANS 14520.
NAF S227 is not listed in the national standard SANS 14520.
4. Most gas standards recommend smoke detection be used for gas suppression systems to ensure the fire is caught at an early enough stage to extinguish the fire. These units require heat (68°C) for them to operate. Heat detectors are not recommended for gas suppression systems.
5. Heat detectors should be within 150mm of the roof for efficient operation. These quartzoid bulbs are generally lower than this distance and some are even lower, mounted on threaded rod brackets.
6. What parameters were used in the design? Was the design based on the operating temperature of the quartzoid bulb 68°C or that of 20°C used for normal room flooding?
7. Recommended maximum operating temperature of gas suppression products according to the national standard is 50°C These units can exceed that when the temperature to burst the quartzoid bulb has to be 68°C.
8. The gas in the cylinder increases in pressure with the rise in temperature and in this case could be as much as 60 bar. These cylinders are not designed to operate at these pressures.
These gasses being discharged at elevated temperatures increase the possibility of breakdown of the gas into hydrogen flouride (HF).
9. With the quantity of gas in these cylinders it can only cover a certain area/volume, is this specified or adhered to? By using more than one module in a room is pointless as the possibility of all quartzoid bulbs reaching the operating temperature at the same time is highly unlikely.
These systems will be offered at a price well below that of a standard gas suppression system BUT will it work or will it be a danger to those who may be in a room at discharge?
CONCERNED - THINK TWICE BEFORE PURCHASING, RECOMMENDING OR INSTALLING THESE UNITS.
- Details
- Written by: Keith Norgate
- Category: Gas Extinguishing
- Hits: 326
The requirement for monitoring of gas cylinders has been in the standards for over 20 years but not often supplied on gas suppression installations, and its importance often overlooked.
When gas is discharged it should produce an alarm to warn personnel immediately and to provide a record of the occurrence.
This is a requirement of the standards (shown below) and should be adopted for all installations.
SANS 369-1 2004: 4.2.1 states:
Confirmation of discharge of fire extinguishing medium should be indicated at the control equipment. The method of deriving the signal should be a pressure or flow switch, located so as to indicate that discharge of gas has occurred from any storage container in the system. For example, in the case of a bank of containers the discharge of gas from any container into the central manifold should be indicated.
The majority of gas cylinders and fire extinguishing control panels supplied in the industry provide this facility and should be connected for all systems.
The inspection bureau have included this onto their checklists for the future.
VISIT www.fireza.net NOW
- Details
- Written by: Keith Norgate
- Category: Gas Extinguishing
- Hits: 379
CO2 gas suppression is still a popular choice for industrial applications, the question is which design method do we use?
Unlike Inerting or Halocarbon agents which have one means of calculation CO2 has four types of calculation to choose between.
- Details
- Written by: Keith Norgate
- Category: Gas Extinguishing
- Hits: 344
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.
- Details
- Written by: Keith Norgate
- Category: Gas Extinguishing
- Hits: 582
Dirt traps are an essential part of any gas system installation but there are several parameters the dirt trap must feature, not like the one below.
If there is any debris or particles present in the Fixed Gaseous Fire Extinguishing Systems pipework, it will be pushed through the pipe on system discharge and can collect in the nozzles at the end of each pipe run blocking the nozzle(s) and adversely affecting the uniform distribution of the gas agent. This may also produce contamination of the protected area/asset.