With no authoritative body, no third party inspections and a lack of knowledgeable consultants or fire officers’ clients are at the mercy of contractors and suppliers.
Although there is a small band of people who are trying to install systems to a level of quality and to comply to standards, the majority of players do not, some deliberately but most due to a lack of knowledge.
There are no gas extinguishing training courses available for contractors in South Africa and they rely on information passed down from the boss who got information from his boss. A lot of this information is incorrect and outdated.
Contractors rely on training provided by suppliers, most of which is generally based on how to connect up their particular products but little about how to adapt this in the field and what installation material should be used. Most contractors do not keep abreast of international trends and are fooled by unscrupulous suppliers who sell gas products dumped in South Africa that cannot be sold in Europe. In some cases the suppliers themselves do not know, or maybe do not care that products they promote are actually banned in Europe or Africa.
In discussions with gas extinguishing system suppliers 90% of systems they supply are not supported with all relevant design parameters. Factors of:
* Room size and height.
* Ceiling void and floor void sizes.
* Cylinder position and banking arrangements.
* Pipe routes via isometric designs
* Room usage.
* Altitude of room.
* Temperature of room.
Are all crucial to a correct set of design parameters being calculated.
Recorded experiences over years include:
* Cylinders filled with anything from soap suds to water.
* Second-hand cylinders installed when new ones are paid for by the clients. Most of which are not even pressure tested.
* Water pipe underrated for required pressure installed.
* Nozzles not even drilled.
* Water pipe fittings installed which are underrated.
* Broken sprinkler heads used as discharge nozzles.
* Incorrect pipe supports used to handle the discharge pressure.
* Orifice plates not installed.
* Insufficient gas used for room volume.
* Wrong design concentrations used.
* Ceiling and doors have been blown out due to incorrect calculations.
Discharge tests
To ensure that money is well spent, one has to actually discharge the system and test the oxygen left in the room after discharge. If one demands a test discharge at time of tender, one will scare off the unknowledgeable contractor.
Sensor Technologies has conducted several real live tests by operation of the fire detectors and allowing the full discharge cycle to take place. Some of the results were:
* TEST 1 - System failure: During the discharge cycle the in-rush current required to operate the gas actuator exceeded the rating of the gas control unit fuse which blew.
* TEST 2 - System failure: A CO2 system was discharged and the required oxygen concentration in the room was not reached (17% oxygen recorded).
Investigations found that not all cylinders discharged and that the hydraulic discharge line had leaked. Under factory testing it was proved that the crimp fittings on the end of the hoses were not correct and leaked under pressure.
* TEST 3 - System failure: A clean agent gas system was discharged. The discharge failed and further testing proved the actuators did not operate because of faulty solenoid actuators.
When determining a gas extinguishing system, the following should be taken into account:
Is the design correct?
Is the installation correct?
Is their enough/too much gas?
Is the pipework of correct specification and installed firmly?
Are the nozzle drillings the correct size/are they installed in the right place?
Who is inspecting the system/does the consulting engineer know what to look for?
Most importantly, test discharge.
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