Technical Bulletins published by the FDIA

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Written by Charles Thiongo

Charles Thiongo

Published: 26 June 2017

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Commissioning a newly installed fire suppression system is one of the most important functions. This is to prove the system functions correctly, the system is safe, the documentation set and certificates are complete and the system is handed over to the client correctly.

The person responsible for commissioning a gaseous fire suppression system will have to go through several key points to ensure the system satisfies the requirements of the relevant standards and ensure the system will suppress a fire in the area it is protecting.

The following are the standards to be referred to when commissioning a gaseous suppression system. Depending on the type of extinguishant used.

SANS 246 for electronic equipment rooms
SANS 306 Part 4 for CO₂ systems
SANS 369 Part 1 - Electrical actuation of gaseous total flooding extinguishing systems
SANS 369 Part 2 - Mechanical actuation of gaseous total flooding and local application extinguishing systems
SANS 14520 - Gaseous fire-extinguishing systems - Physical properties and system design

There are two aspects to a gaseous fire suppression system, the electrical part and the mechanical part.

Electrical installation

The fire detection system must meet the basic requirements of SANS 10139, SANS 246 and SANS 369-1

The following points need to be considered:

1. Ensure the appropriate type of the detectors are installed and sufficient to cover the area they are protecting (1 per 50 m² minimum). The wind speed and flow direction of the air-conditioning equipment has been taken into consideration as it influences the quantity of detectors to be used.
2. Ensure that the detectors are installed in coincidence connection meaning 2 different detectors have to operate to activate the suppression system. The same applies for the ceiling void and floor void detectors.
3. The Gas Control Unit is located at the entrance of the protected room with a manual switching device to enable mode of operation of the system to be changed from Automatic to Manual when personnel are entering the protected area.
4. There are visual and audible indication at the Gas Control Unit to show the system status. This should also be provided at every entrance to the protected room. The operation of repeaters must function in conjunction with the main fire control panel to ensure that there is interlinking of the devices.
5. A manual release switch or break glass unit to release gas has been provided. The switch should be yellow in colour with operational instructions and signage indicating function and method of operation of the device.
6. If the area is normally occupied when the system is in automatic mode then a hold switch should be provided to delay the countdown to discharge whilst the switch is held down. Upon release of the switch and provided the system is still in alarm state, the countdown should start from the beginning.
7. Audible and visual warnings are provided for, both inside the protected area and outside the area. The FDIA is promoting uniformity for audible and visual warnings for gas protected areas. Below is an operational philosophy we are asking all contractors to adhere to.

 

Electronic areas

Electronic areas have to comply with SANS 246 and there are guidelines given on which type of detectors are to use in these electronic equipment installations.

The type of detectors will be determined by the category of risk identified. Three categories are mentioned in the standard and they are:

C – Medium Risk
D – High Risk
E – Critical Risk

A High Sensitivity Smoke Detection / Aspirating system is the only type of detection recommended for category D and E.

For High risk category D and E rooms it is a requirement that aspiration detection is installed at the return air grill to sense smoke picked up in the movement of air.

The type of detection, wind speed and wind flow direction of the air conditioning equipment influences the quantity of detectors to be used.

All of the above become the responsibility of the commissioning technician to ensure everything is installed as per the SANS requirements and functions correctly.

Mechanical installation

This section includes the cylinders and installation of gas distribution pipe and fittings.

The mechanical check should involve the following:

1. Every gas system installation shall be provided with a gas hydraulic calculation which has to be checked by the commissioner.
2. The dimensions of the room should be measured to ensure they are the same as the hydraulic calculations provided.
3. The pipe size and layout is as per the hydraulic design.
4. The pipe fittings used shall be in accordance with the standards and be able to withstand system frictions and pressures.
5. The nozzle size and type is as per the design.
6. There is a dirt trap installed at the end of each pipe so that dust and foreign matter does not impede nozzle orifice.
7. The pipe work and cylinders are securely fixed so that there is no movement during discharge.
8. The gas cylinders are clearly labelled, showing the type of gas, capacity of cylinder, quantity of gas inside, date and approvals.

 

Room integrity test

All cable and other penetrations or openings into the room are adequately sealed to prevent extinguishant gas escaping out of the room.

A room integrity test should be carried out to confirm that the extinguishant gas will remain in the room for the required time (10 minutes for clean agent gasses) and a report for the room integrity test included in the documentation.

Some rooms will have openings during normal operations like MCC rooms to allow to air circulation and in such cases dampers will have to be provided for. Aircon shut down units for server rooms need to be interfaced to the suppression system to switch off the aircon during discharge, if they are supplying fresh air to the room but recycling units can be left running and can actually assist in the dispersion and mixing of the extinguishing gas with in the risk area).

The type of agent used may necessitate the use of pressure vents, especially if it is an inert gas used as an extinguishant. This is to prevent damage to walls and windows due to increase in pressure within the room, caused by the gas discharge.

All of the above must be either witnessed by, or conducted by, the commissioner.

Documentation

The documentation for a suppression system should include the hydraulic calculations for pipe work, design concentration for the type of gas used, report on room integrity test, certificates and approvals for the system and equipment used.

A signed certificate should then be given to the client that verifies the installed system operates correctly in accordance with requirements laid down by the designer and that the commissioner carries liability for the correct operation of the system.

Gas commissioners shall be registered at the SAQCC Fire and carry an identity card of such.

We encourage end users to utilise FDIA registered companies as they have the relevant registrations, training and experience and are committed to working to required standards.

 

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Written by Jolene van der Westhuizen

Jolene van der Westhuizen

Published: 18 April 2017

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It is with saddened hearts we hear of the passing of Barry Botha.

Barry became one of the leading lights of the industry with an in depth knowledge of his subject.

He was an affable character and a friend to many of us

He will be sadly missed

Rest in Peace Barry.

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Written by Charles Thiongo

Charles Thiongo

Published: 21 May 2017

Hits: 2061

Kudos to the fire fighters from Johannesburg CBD for their swift response following a fire in Braamfontein, in a multi -storey building in April 2017. It was reported in both the print and electronic media that no one was severely injured and only a few people were treated for smoke inhalation.

The need for any building to have a fire detection system will be dictated and enforced by local authorities having jurisdiction in that area or by the property insurers. The category and type of fire detection system is determined by a fire risk assessment carried out by a competent person, in consultation with the building owners / users and other consultants. When the category of the system is clearly defined, this then will determine whether there will be a need for automatic detection and where it will be installed, or if it will be manual call points only, or as in most cases a combination of both. Category L systems are automatic fire detection systems intended for the protection of life. This category of system is ideal for high rise buildings since the main objective of this category is an effective evacuation of occupants.

The L category is sub-divided from L1 to L5 and the designer of the system will determine the appropriate sub-section applicable to that particular building. In a high-rise building, Smoke detectors will be installed on all escape routes, lift lobbies and stairway landings. For an L1 Category, it will be detection in all areas of the building. SANS 10139 states that “Manual call points need to be prominently sited, readily distinguishable from non-fire alarm call points and need to be distributed such that, from any point in the building so that it is impossible to leave the storey or the building without passing a manual call point”. Sounder pressure levels should be taken into consideration so that in each and every part of the building the sound is clearly heard, more so if there are people sleeping in that building.

For a multi-storey building the designer of the fire detection system should give consideration that the fire detection system will be there to support the fire strategy of the building especially the evacuation procedures. The fire alarm signal should be audible and distinct, leading to an orderly evacuation of the building into a designated safe area. Depending on the size of the building, the designer of the fire alarm system will decide whether there is need for a staged or phased evacuation.

SANS 10139 Part 8.12 addresses staged alarms. The document states: “in a staged fire alarm system, the initial warning of fire is given in a restricted area, or is restricted to key personnel, but can be extended in further stages to warn, ultimately, all occupants of the premises. This arrangement might apply regardless of whether the alarm is triggered by a manual call point or an automatic fire detector, or it might apply only to alarm signals triggered by automatic fire detectors.”

The standard further states that “in certain large or high rise buildings, it might be desirable to evacuate first, those areas closest to the fire and immediately above it. This section also gives information on phased evacuation, whereby the floor of fire origin, the floor immediately above (and, often, any below ground areas) are evacuated as a first phase. Thereafter, each subsequent phase involves evacuation of two floors at a time, until all floors are evacuated in a number of such phases. This arrangement enables the number and/or widths of stairways to be reduced; under these circumstances, it is important that no control is provided to evacuate the entire building in a single phase, as there will be insufficient stairway capacity for simultaneous evacuation of all occupants.”.

An evacuation system is highly recommended to provide voice instructions for safe and orderly evacuation from a building.

SANS 7240-19 covers Evacuation Systems and the document provides guidance on the various aspects of a sound system for emergency purpose.

The evacuation system according to SANS 7240-19 should have the following as a minimum requirement especially for high rise buildings:

1. Capability to operate automatically or manually and have manual controls and visual status indicators.
2. Able to receive alarm signals from an emergency detection system(s), and receive audio messages from emergency microphones.
3. Ability to determine signal priority and routing and be able to cause audible warning signals to be broadcast to emergency loudspeaker zones.
4. It is important that the system is able to automatically supervise the correct functioning of the system and give audible and visible warning of specified faults.

For existing buildings, the onus is on the building owners / users to ensure that the fire alarm system is serviced and tested regularly by a competent company and the records are kept. For new buildings, it will be all the relevant consultants in various disciplines working in harmony to ensure a reliable and functional fire detection system in place. The fire department also needs to be involved, inspecting and ensuring that fire detection and fire protection systems for high rise buildings are serviced regularly and are in good working condition. It was unfortunate that when the fire department arrived in Braamfontein to combat the fire, they found out that the fire hydrants did not have any water supply.

Ensure that you use an FDIA registered company to obtain proper advice on the protection of your building. For comments and enquiries please contact the FDIA on This email address is being protected from spambots. You need JavaScript enabled to view it.

 

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Written by Charles Thiongo

Charles Thiongo

Published: 12 April 2017

Hits: 3815

Following a recent major fire in a Durban Warehouse which started on the 24th of March 2017 we see it necessary to discuss ways in which warehouses need to be protected against fire so that a fire can be detected early and contained before it gets out of hand. As was experienced in Durban, fires emanating in a warehouse can cause a lot of damage if not contained at an early stage. There is also the environmental pollution that occurs to the surrounding areas due to the large amount of smoke which in a lot of cases can be toxic.

Installing a compliant and functional fire detection system for a warehouse requires proper and thorough planning to decide which type of systems to install.

The size of the warehouse, activities within the warehouse, being manned or unmanned and available funds will be the major items that will determine what type of system gets to be installed.

Water sprinklers, hydrants and fire extinguishers play a key role in initial firefighting and are a requirement in nearly all cases, but our key focus is early detection that will enable the exact location of fire to be detected and measures taken to extinguish or contain the fire at an early stage.

The designer of the fire detection system will need to take into consideration the layout of the warehouse and activities that will be happening there during normal working and even after hours. It beats the purpose to install smoke detectors in a production warehouse where there are fumes or dust produced in fairly large quantities during normal operation, as false alarms will keep occurring.

One must consider the servicing of smoke detectors in heights more than 10 meters, this will require scaffolding or a Cherry Picker and it may not even be possible to access the smoke detectors in some areas of the warehouse if there are machines or racks that will be installed after installation of the smoke detectors.

Point type smoke detectors cannot be installed in heights of more than10.5 meters. Some warehouses have openings at the roof sides which allow for natural ventilation and light, some have smoke vents at the roof peak; consideration needs to be taken to ensure that dust and rain will not get into the detection devices installed at roof level.

The probability of stratification of smoke needs to be taken into consideration when siting smoke detectors or any other detectors on the roof.

Stratification occurs in summer when the sun heats the roof sheeting and creates a hot air layer at roof level within the warehouse, during a fire condition, if the hot air layer temperature is greater than the smoke when it reaches this point, the smoke will not be able to penetrate the heat layer and therefore detectors may not function or in the very least the alarm will be seriously delayed.

Fire detection types

It has already been mentioned that standard point type detectors cannot be installed above 10.5 meters which leaves the fire detection designer only two choices, beam type smoke detectors or aspiration detectors.
Beam detectors are generally well suited for large warehouses due to the flexibility they have in providing coverage for over large areas and heights up to 25 m. Beam detectors are easily accessible and easier to service than smoke detectors as there will be fewer in number in comparison to smoke detectors and the control unit will usually be installed on the wall of a warehouse as compared to smoke detectors which have to be spread on the entire roof.

Beam detectors need a clear line of sight in order to operate optimally and cannot be installed more than 600 mm from the top of the roof. This is a trap many fire detection companies fall into as in today's roof type structures it is not easy to achieve these two parameters and they end up installing beam detectors further away from the roof and taking a risk that the smoke does not bypass these detectors on the way to the roof.

Beam detectors will also not operate correctly if installed on structures that are prone to movement. Most warehouses are built with iron girders and corrugated iron sheet which expands and contracts as the temperature varies. Installing beam detectors on such structures will affect the operation of a beam detector when the line of sight is lost between the transmitter and receiver.

Aspiration smoke detectors is the second option to consider. The ASD (aspirating smoke detector) operates by actively sampling air from a protected area via multiple sampling holes in a pipe network. The air sampled is then transported to the aspirating control panel to detect the presence of smoke. An ASD provides many programmable levels of smoke detection, from a very high sensitivity through to low sensitivity as required. An ASD is approximately 100 times more sensitive than a point smoke detector and it can even detect smoke that is not yet visible to the naked eye.

The ASD is not affected by the roof structure, does not require line of sight and provides better coverage than the beam detector.

Although the initial installed cost of an ASD may be higher than smoke or beam detectors the ongoing maintenance costs are greatly reduced as the control equipment and filters that require maintenance are installed at eye level and there is no need for high lifting equipment.

Whichever solution is decided upon one must also ensure that alarms raised by the equipment are quickly attended to and after hours the alarms are extended to a remote, monitoring service, employee or direct to the fire department.

The most effective fire detection system is useless if the alarms are not reacted to promptly.

Each warehouse is different and one must think carefully to chose the best solution for that warehouse. Ensure that you use an FDIA registered company to obtain proper advice on the protection of your warehouse.

For comments and enquiries please contact the FDIA on This email address is being protected from spambots. You need JavaScript enabled to view it.