Ductwork
Designs on compliance
and DW/172, the construction standard for kitchen extract systems. You would think that as long as ductwork is installed to these standards, it would be relatively simple to keep them compliant with TR/19, the standard for ongoing ductwork hygiene and fire safety cleaning. Sadly, this is simply not the case in far too many installations. Strangely, the construction standards don’t always aid ongoing compliance, so it may be necessary to modify the system at its very first clean. Cleaning a system will be a regular task over
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many years, yet DW/144 does not currently include a requirement for ductwork installers to install the full gambit of doors to allow the ductwork systems to be inspected and cleaned in compliance with TR/19 guidelines. In far too many cases, it becomes necessary, at the very first clean, to install additional access doors in order to reach inaccessible parts of the system. In the worst scenarios, it simply is not possible to
retrofit all the access doors required. This may be because once the ventilation system has been in- stalled to the correct standard, a beam, wall or a stair- way may have been constructed across the run of ventilation ductwork, or it may have been boxed in in some other way, leaving a problem for the future. In these instances, there are two not very appealing choices; either the modifications needed to bring the system into compliance with TR/19 will be very costly indeed; or it won’t be possible to clean it effectively and the system simply won’t be TR/19 compliant, even though it was compliant with DW/144 when installed. While it is not great for a ventilation system de- signed to provide fresh air to the building not to comply with TR/19, in the case of a kitchen extract system, it can be life threatening, due to the fire haz- ard that non-compliance creates. Fat, oil and grease caused by cooking will
accumulate in kitchen extract ductwork, no matter how spotless the kitchen may be and this grease layer represents a serious fire risk. Fuelled by grease deposits, fire can spread through the ductwork, which can act like a chimney. In some properties, for exam- ple, where a fast food outlet is situated at ground floor level with apartments above it, fire may spread from a commercial kitchen to residential accommodation. Controlling this grease layer is fundamental in ensuring compliance with Article 11 of the Regulatory Reform (Fire Safety) Order to minimise fire risk within kitchen extraction systems. TR/19 compliance is
February 2017
he current standards which must be met in ductwork design and construction are DW/144, the ventilation ductwork installation standard,
Ventilation cleaning in progress
In far too many cases, it becomes necessary to install additional access doors in order to reach inaccesible parts of the system
An example of a Swiftclean Building Services access door
required to ensure that the film of accumulated fat, oil or grease is controlled within a 200 micron tolerance layer, to minimise fire risk to an acceptable level. The amount of grease which constitutes a fire hazard is far less than you might think; 200 microns is only about half the thickness of the average business card; which is why access for regular cleaning is so vital. The problem of ongoing compliance would be helped enormously if every system were designed to meet TR/19 guidelines from the outset, as this would ensure that every part of the system would be acces- sible. We can understand why systems are designed to DW/144; fewer access doors does make the system slightly cheaper; but this is a false economy if the sys- tem has to be modified at the first clean. The added initial cost of including the number of access doors required for TR/19 compliance is actually far less than the price of retrofitting doors at a later stage. Not surprisingly, retrofitting access doors will cost more than including them in the original installation.
It should also be safe for the staff cleaning to TR/19 to use the access doors, so in some places, there may be a need for an access platform so that technicians can access the system with minimal risk, especially if working at height. Having seen many cases of system design which
complies with DW/144 or DW/172 standards, but which does not facilitate cleaning in compliance with TR/19, we now strongly believe that TR/19 ought to be taken into account when designing and installing every new system.
Installation and ongoing use should not be re-
garded as two separate functions. In almost every other system in a property, initial thought is given to how the building user will access and use the sys- tem. This should be the same for ventilation. The health, wellbeing and safety of every building occu- pant could depend on it. That alone should be enough reason to keep TR/19 firmly front of mind when designing and installing every new system. •Gary Nicholls is the managing director of Swiftclean Building Services as well as a member of the BESA steering group for TR/19
www.heatingandventilating.net
Gary Nicholls
TR/19 is the leading industry guidance document for hygiene and fire safety cleaning compliance in ventilation ductwork and Gary Nicholls of the Building Engineering Services Association (BESA) steering group for TR/19, believes that it should also be the main influence on ventilation system design
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