Technical Bulletins published by the FDIA
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Fire detection systems are primarily designed and installed to provide warning about a possible outbreak of fire. The warning provided enables early evacuation thus protecting life and if possible initial emergency fire-fighting may be undertaken to inhibit further spread of the fire thus protecting the property and the contents thereof.
The fire detection system designer after doing the risk assessment and consulting with the relevant parties which may include the legislative authority having jurisdiction in that area, the insurer, the architect, the mechanical / electrical consultant and the owner or occupiers of the building, comes up with a document which among other things will have a bill of quantities, specification for the system, category of the system and provides design drawings which will give clarity and direction to the installer on the fire detection system to be installed.
The designer of the fire detection system must therefore understand what objective is to be achieved by the system and what considerations to give to each type of building as each building will present different challenges and scenarios. The designer is the one who decides which type of devices need to be installed, where they need to be installed and why they need to be installed there. The design task is therefore critical, carrying a heavy responsibility and should not be taken lightly because any mistake, misconception or ambiguity at this stage will eventually have an effect on the installation and the operation of the system, which may lead to unnecessary loss of property or worse still, the loss of life.
The designer carries a liability for the system design.
SANS 10139 provides guidelines and recommendations for the planning, design, installation and maintenance of fire detection system. Three categories are mentioned in the document:
- Category M systems are manual systems and, therefore, incorporate no automatic fire detectors.
- Category L systems are automatic fire detection systems intended for the protection of life. They are further subdivided into L1, L2, L3 L4 and L5 categories.
- Category P systems are automatic fire detection systems intended for the protection of property. They are further subdivided into P1 and P2 categories.
The above is a basic mention of the standard and any person doing fire detection system design should not only have a copy of the document but should have a thorough knowledge of the contents therein. The document is not a rigid standard with inflexible requirements but contains recommendations that will be suitable in most applications. This means that a designer may adopt a variation on the basis of a risk assessment, engineering judgement or a practical scenario with regard to installation.
Any variation done should however be clearly identified and documented as recommended in the standard so that all relevant parties are aware and agree to the variations. The variation should also be listed in the design certificate issued by the fire detection system designer.
SANS 246 is the South African standard for fire protection of electronic environments and was updated at the end of 2015 with many changes to cater for the complication of ever changing technology being utilised in computer room environments. Fire detection for computer rooms is becoming a specialised skill with higher air flows and "hot aisle/ cold aisles" configurations and it is important to utilise the services of designers with experience in these environments.
Please note that it is a legal requirement in South Africa from the Department of Labour for persons designing fire detection systems to be registered with SAQCC Fire as a fire detection system designer. Training is available for those already in the industry who would like to improve their skills on fire detection design.
By utilising FDIA companies it provides an element of comfort to end users knowing they comply with all the requirements of these standards.
Feel free to contact FDIA via email This email address is being protected from spambots. You need JavaScript enabled to view it. for any questions, comments or concerns regarding fire detection system design.
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The FDIA records now reflect 48 members and increasing, this despite the arduous entry requirements to the Association.
The companies that take the fire detection industry seriously want to be recognised for the professional service they offer.
Barriers of entry to the fire detection industry are open to all and many companies will take on a fire detection installation when times are tough in their own industry.
The legal requirement for SAQCC Fire registration of technicians is often overlooked by consultants and end users, often resulting in the cheapest quote being preferred.
Continuous efforts are being taken by the FDIA with persuasive advertising, led by Charles Thiongo to guide consultants and end users to support the Association members who specialise in fire detection and gaseous suppression and provide quality installations.
FDIA members attended the IFE golf day held recently to promote the FDIA
THE FDIA TAKES LIFE SAFETY AND PROPERTY PROTECTION SERIOUSLY!
Support the companies that care!
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Type
The pipe can be of any material with a smooth bore but is generally accepted as PVC type. Aspiration pipe can be any colour, it is not specified in SANS 10139 or EN 54-20. The manufacturer states pipe can be red or white in colour but is generally red to differentiate it from electrical conduit. Pipe is to be 25mm diameter.
Installation
Sampling pipes must be installed within 600mm of the top of the roof.
This presents a problem in South Africa for pipes installed against tin roofs. ABS pipe expands by 0.1% with every 10ºC and with the high temperatures experienced inside South African roofs the ABS pipes end up bowing and sagging.
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Hold Times
All clean agent gasses, at a concentration above the extinguishing concentration, have to be held for a period of 10 minutes in an enclosed environment. SANS 14520 - 7.8
CO2 used on all total flooding deep seated fires shall be maintained for 20 minutes. SANS 306 - 10.5
Room pressure testing
All gas system supply companies offer room integrity testing; experience in this field reveals that rooms with suspended ceilings and/ or partition walling rarely meet the hold time.
Leakage through these two areas is difficult, if not impossible, to solve.
Halocarbon agents present a bigger problem than inerting agents due to their heavier weight.
Room flooding
Although in SANS 246 - 8.2.1 it does acknowledge partial protection it recommends that the entire enclosure be flooded with suppression gas.
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Beam detectors are ideally suited for large open plan warehouses, or are they?
Most manufacturers call for a clear space of 500 mm for the beam away from obstructions; this is especially important for reflective type beam detectors.
There are reported incidents of the beam being reflected from the roof structure and not the shiny metal plate. We may believe the entire roof structure is covered when only half of it is!
Please ensure that technicians test the beam detector AT the reflective plate, not at the transmitter.
