A Day in the Life of a Smoke Control Maintenance Engineer
As with all systems in our modern dwellings and offices, they need to be maintained at regular intervals. Maintenance often takes place when there is a failure of a part or parts which then has to be replaced. This approach may be acceptable for general building components, but when we are looking at life - safety systems, ‘preventative maintenance’ is crucial and a legal requirement.
All smoke control systems are maintained on a 6 monthly basis to ensure that all components are fully functional and performs to the original fire design specification for the building by providing continued reliability in the event of a fire. This preventative smoke control maintenance conforms with, BS 9999, BS 7346, Part 1, 1990 and The Building Regulations Approved Document B.
The Regulatory Reform (Fire Safety) Order 2005 (RRO) came into force in 2006; it has changed fire safety requirements and effects all UK organisations. The RRO outlines considerations and requirements for fire safety measures; these include conducting a risk assessment, training, equipment and maintenance.
The writer met up with Steve Birch (an SE Controls Maintenance Engineer) for the day, to visit and help maintain a typical smoke ventilation installation. The objective was to discuss system maintenance and identify typical problems faced by these systems in use.
In apartment buildings it is assumed that a fire is most likely to occur in an apartment. The principle is for the occupant of the apartment which is on fire to escape and the other residents to stay put (they may not even know there is a fire). As the occupant of the ‘fire’ flat escapes, it is probable that some smoke will get into the common corridor or lobby. It is important to ventilate this smoke to prevent it getting in to the common stair and it is the protection of this common stair that is the primary objective. This ventilation also affords some protection to the common corridors/lobbies but this is a secondary benefit – not a primary requirement.
To ventilate this smoke from the corridor or lobby, Approved Document B recommends that if an external window is located on the external wall an Automatic Opening Vent (AOV) can provide effective smoke ventilation. But typically developers are utilising the external wall by adding apartments to create a scenic view for the occupants. In this situation a vertical smoke shaft is provided with either an automatic opening smoke shaft door or damper opening into the smoke shaft and exhausting the smoke into the smoke shaft and out the top of shaft via an AOV.
On each landing or lobby, located on the ceiling is a smoke detector which when activated simultaneously triggers the opening of the corridor or landing AOV, smoke ventilation shaft roof AOV and escape stair AOV. Once opened the system ensures no other doors on the smoke ventilation shaft can be opened ensuring smoke does not transfer between floors.
Testing these systems, the smoke detectors are subjected to smoke tests via a telescopic smoke testing unit each sensor should then operate the corresponding AOVs. This is repeated on each floor after resetting the system. Every twelve months the smoke detectors are cleaned to reduce contamination and false alarms.
To ensure that ‘trap hazards’ are not present when motorised systems are closing, switches adjacent to the AOV need to remain depressed until the doors are fully closed. This configuration is known as a mitigating the risk of the trap hazard to a passing occupant. All AOVs within 2.5 m of floor level must have some form of ‘mitigating procedure’ or safety device fitted and checking these forms part of the inspection.
Following inspection of the system in action, all AOVs, including the doors, windows and roof vents are inspected for signs of wear and tear’ and fixings are checked then lubricated and cleaned if necessary. Any parts requiring replacement are duly noted on a report. Reports are then passed to the managing agents who often look after the building on behalf of the owner. Where failures have occurred during inspection the managing agents would agree a course of repair.
On many installations a repeater panel would be selected to be installed onto a smoke ventilation system. The repeater panel would typically be located near the fire service access entrance of the building to provide system indication.
The repeater panel indicates green lights to show the system as being healthy, a red light shows that the system has been activated in a particular floor or zone and an amber light indicates a fault. Should an amber light or red light remain present on the panel, the maintenance engineer should be called out to undertake a reset or a repair.
Whilst this product is not a requirement under Approved Document B, it is recommended as it provides essential system information for the fire service, client and maintenance engineer.
Within the control panel a 24V battery back-up supply is provided which will continue to operate the smoke ventilation system in the event of a mains supply failure. During maintenance visits batteries are checked for performance and recommended for replacement where they fall below a certain standard. Batteries last on average 3 to 5 years.
So far we have discussed the routine maintenance and repair of systems, but the maintenance engineers’ responsibilities go a little further. Occupiers of a building can often unknowingly influence and compromise the correct working of smoke ventilation systems. One of the most common potential problems is ‘clutter’.
Smoke ventilation stacks are fitted with grills at floor level to ensure safety when the doors are opened. These grilled areas have been used as storage areas by residents. Roof light openings can be compromised by items placed on the roof, on or near to the roof light. Penthouse occupiers can unknowingly cause problems with trees and shrubs which will interrupt the opening of the roof light and could lead to a build up of smoke in an incident. These issues are recorded by the maintenance engineer and again it is up to the managing agents to advise the occupier of the issues and agree a course of action.
As systems become more intelligent and more cost effective to install, cable management and self diagnostic systems are now emerging. Using a much simplified wiring system with less connecting wire, these systems monitor motor speed and resistance to determine the correct operation of the device. Should the ‘load’ profile change, this would indicate a fault and would initiate a call out. SE Controls have developed ‘OSLoop which works on this principle, each zoned area ‘can be linked and where a cable fault or incorrect voltage of the actuation is detected a maintenance engineer can be called to rectify the problem in the particular area. These more advanced systems meet the required standards of the forthcoming EN 12101- 9 and 10, ‘Control Panels and Power Supplies’.