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SMOKE CONTROL SYSTEMS SAVE LIVES But only if they are functioning correctly
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When fire breaks out, every second counts. Safety systems must work properly – because if they don’t, lives could be put at risk. Olly Lucas, Service Manager, SCS Group, has some expert advice about smoke control systems for building managers and anyone responsible for fire safety in commercial premises.
moke control systems are critical to ensuring the safety of
individuals in the event of a fire. Smoke build- up, if not ventilated
correctly, can quickly overcome an individual long before the fire itself becomes an immediate risk.
In a fire, smoke control systems limit and control the movement of smoke throughout a building. These systems maintain clear escape routes for people in the building and protect firefighters entering the building. It is vital that smoke control systems can be relied upon – and that means making sure they are maintained and working correctly.
The most common smoke control system today is the ‘smoke shaft’ system. It uses a builder’s work shaft to ventilate smoke away from enclosed spaces or space where it would be unfeasible to use automatically opening ventilators (AOVs). It can be naturally or mechanically ventilated, depending on the flow rate required to meet the requirements of the building’s fire strategy.
Typically, a smoke shaft system includes a dedicated smoke detection installation to monitor common corridors. When smoke is detected, an automatic damper into the smoke shaft opens on the fire floor. At the same time, roof- mounted extract fans start to remove the smoke. Fresh air is drawn in from a ventilator at the top of the stairwell. The fans can be ramped up to high speed to provide extra protection during firefighting operations by using the fireman’s override switch.
To achieve this efficiently, while also providing day-to-day extraction of heat from common areas, modern installations use a purpose- designed automatic ventilation software programme that ensures failsafe operation in fire conditions.
Maintenance
Maintaining smoke control systems is critical to ensuring their optimum performance in the event of a fire. The Regulatory (Fire Safety) Reform Order (RRO) 2005 details the requirement for the maintenance of life-safety systems, but this can often be overlooked or not fully understood.
The RRO (2005) stipulates that the responsible person must ensure that the premises, facilities, equipment and any devices for use by or for the protection of firefighters and relevant persons, are subject to a suitable system of maintenance and are maintained in an efficient state, in efficient working order and in good repair. The RRO (2005) states that it is an offence for any responsible person or any other person with control of a premises, to fail to comply, where that failure places one or more relevant persons at risk of death or serious injury in the case of fire. Therefore, we understand from the RRO that life-safety systems must be maintained by law. Failure to do so could result in death or injury and prosecution for failing to comply. But how often should a smoke control system be maintained? What constitutes appropriate maintenance? And who should be considered competent in undertaking maintenance to such important equipment?
Standards
The maintenance requirements for natural (vents) and powered (fans) smoke control systems are set out in BS EN 12101 and BS 9999. These standards stipulate that such life critical equipment shall be included in the Building Services maintenance schedule. A maintenance and function test schedule should be prepared specific to the system. All unsatisfactory findings or defects must be recorded and reported to the building management. The maintenance of equipment must be in accordance with the manufacturer’s instructions. BS EN 12101 and BS 9999 set out the frequency of tests and what should be checked.
Weekly tests should be carried out to check the operation of the system. For mechanical systems, checks should be made to determine whether the fans are running satisfactorily and that the ventilation system has operated. Where there is a back-up generator in place, the fuel level should be checked and topped up as necessary.
Monthly tests should also be carried out. During these, the failure of the primary power supply should be simulated and a check made
14 BUILDING SERVICES & ENVIRONMENTAL ENGINEER OCTOBER 2016
that the system has automatically switched over to the secondary power supply. Where the secondary supply is via a back-up generator or power cell (battery or UPS), the secondary supply must be able to energise the system for a minimum of one hour. A zero airflow condition should be simulated to check that the system switches automatically to the standby fan/s and that they are running satisfactorily.
Weekly/monthly checks are usually carried out by the building’s general maintenance personnel who should have received hands-on training from the system’s manufacturer/installer.
In reality, these checks are often overlooked. This may be because the importance of frequent life safety system checks is not fully understood. The service provider of the smoke control system needs to be actively encouraging short-term checks of the system, offering training to site personnel and a log book so that all checks can be recorded and monitored. SCS Group has a maintenance logsheet available to download at
http://groupscs.co.uk/services/ maintenance/
BS EN 12101 states that in addition to weekly and monthly tests, the entire system should be tested annually as a minimum requirement. Where weekly or monthly checks are not carried out, the inclusion of a six-monthly function check in addition to the annual service by the specialist service provider becomes ever more important.
Operation manual
A typical manufacturer’s operation manual will specify a series of checks that should be carried out, which will form the basis of the engineer’s reports that are submitted following maintenance. For each floor of a building this will include: uTesting of smoke detectors using test gas and applicator uOperation of all local override switches checking operation of door/window actuators uCheck rotation of extract fans uMeasurement of volume flow rate at each damper and record against design criteria uSimulate fire conditions by removing alarm link and check for operation
uSimulate primary power failure and check for integrity of secondary power supply uSimulate flow failure and check for automatic switch-over to standby fan.
To achieve full detailed maintenance and point-to-point testing, a minimum of 20 minutes should be spent per floor. In addition central extract plant, PLC/VSD control systems and daily ventilation must be maintained. This does not account for delays that can occur when obtaining access to all key areas of a building. Without taking the time necessary to check every element of a smoke control system, the responsible person cannot have confidence that the system is functioning correctly, or will operate when required in fire conditions. As a manufacturer and installer of smoke control systems, SCS Group stipulates a rigorous maintenance procedure that should be undertaken annually as a minimum. Due to the complexity of modern smoke control systems, ever- changing climatic conditions within the UK and absence of
weekly/monthly testing, SCS Group strongly recommends that a six- monthly function check is undertaken in addition to the annual service.
Smoke control systems should only be maintained by a competent person with specialist knowledge of smoke control systems, training on the particular system installed, adequate access to spares and sufficient information regarding the system. In addition to having experience and training of smoke control systems, the service engineer needs to have an industry recognised level 3 electrical qualification. Training in PLC systems is essential to enable an engineer to interrogate, repair and update the automated software programs utilised in modern smoke shaft systems. The person responsible for the building should ensure engineers do hold the correct qualifications before any maintenance work is carried out on a smoke control system. When selecting a contractor to maintain a smoke control system, SCS Group would advise you to choose a member of the Smoke Control Association (SCA).
groupscs.co.uk VISIT OUR WEBSITE:
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