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Once a fire of this type takes hold it can be incredibly difficult to contain as it often spreads rapidly through the ductwork system to parts of the building that even trained fire crews would have trouble accessing in a short space of time
producing guidance on cleaning requirements. ADCAS strongly recommends that DW144, the specification for sheet metal ductwork, is referred to when designing and installing kitchen extraction ductwork. This guidance includes consultation with a cleaning company at the design and implementation phases to ensure the ductwork is accessible for cleaning and maintenance. Under the regulation EC852/2004 on the hygiene of foodstuffs Annex II, Chapter 1 section 5 “there must be suitable and sufficient means of natural or mechanical ventilation. Mechanical airflow from a contaminated area to a clean area must be avoided. Ventilation systems must be so constructed as to enable filters and other parts requiring cleaning or replacement to be readily accessible.”
Inspection and cleaning
Reducing the fire risk means routine inspection and cleaning of ductwork systems by a specialist and it’s strongly recommended that post-installation cleaning is carried out immediately before commissioning, ensuring that the newly installed system is dust and contaminant-free from the very start. It should be stressed that ductwork cleaning is very much a job for a specialist contractor and would not commonly be included for or undertaken by a ductwork installation contractor. When it comes to cleaning and maintaining ductwork, access is key. It is a legal requirement under the requirements of EC852/2004 Annex II Chapter 1 paragraph 5 enforced by the food standards agency that the construction and installation of all kitchen related ductwork is ‘readily accessible’. From the outset it’s important to assess whether or not access points for cleaning and maintenance are fit for purpose. With this in mind, the following points should be high on the list of design considerations:
• Can access panels be removed by an operative without obstruction?
• Can access panels be accessed by an operative using a stepladder or tower?
• Can access be gained without having to move fabrications such as fan or attenuator housings, supports and lighting tray conduits, or the fans themselves?
The careful placement of access doors will ensure that future maintenance is straight-forward and hassle-free for the cleaning technician – the DW/144 document contains detailed tables specifying recommended access panel locations and sizings and this information is also consolidated in the ADCAS Guide to Ductwork Cleaning Requirements and Access Doors.
Additional considerations
In order to reduce the number of inaccessible sections the ductwork can be kept as short as possible, turning it into a kitchen design feature and ensuring it is not hidden away and forgotten about, whilst removing the need for specialist access equipment or expensive cleaning techniques.
In kitchen environments, filter systems can be used to protect the fan and should be routinely monitored, cleaned and, when necessary, replaced. Carbon filters can be used to remove odours and smells associated with cooking, while wool-type pre-filters may also help reduce contamination at the point of entry into the duct system. Fire detectors installed as part of a fire suppression system should not be placed inside the ducting as they can obstruct service and maintenance technicians and hamper the cleaning process. ADCAS and NAADUK are also looking into the use of Tek screws, also known as self-drilling screws or self-tapping fasteners. Protruding screws inside a duct can
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potentially damage or destroy brushes used in the cleaning process or can cause abrasive injuries to cleaning technicians. Members have asked where at all possible that these types of screws are modified or not used as they can inhibit the cleaning process.
Requirements and repercussions Using an underqualified or inexperienced kitchen ductwork cleaning team could have serious repercussions for building owners/operators as responsibility for taking the relevant steps to safeguard occupants. Current standards and schemes require the client to be fully informed of any access issues combined with recommendations in an advisory note or post clean report.
The 2005 Regulatory Reform (Fire Safety) Order makes it clear that the responsible person must ensure there is a suitable maintenance plan in place and all equipment should be kept in good working order. If the worst were to happen and there was strong evidence to suggest that a kitchen fire was triggered by poorly maintained ductwork then the responsible person or persons could end up facing large fines or even serving jail time. The importance of regularly cleaning ductwork systems is now widely understood so it’s vital that access points are considered at the design stage and everybody understands their responsibilities. Designers should seek advice from a specialist cleaning contractor to ensure that any new design will not thwart attempts to clean and maintain the system further down the line. Where kitchen extract systems are concerned, failure to maintain systems to a satisfactory standard will not only invalidate insurance policies but could also lead to extensive damage to property and heighten the risk for building occupants – accessible ductwork and qualified cleaning contractors will guarantee a safer environment for everyone.
If there was strong evidence to suggest that a kitchen fire was triggered by poorly maintained ductwork then the responsible person or persons could end up facing large fines or even serving jail time
February 2020 !"
Ductwork
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