PIPES AND DUCTWORK No matter the precautions taken, the very


nature of the worksite determines that there will always be a chance that impurities will find their way into the infrastructure. The DW/44 Specification for Sheet Metal Ductwork reaffirms this assertation when it states, “Practical experience shows that due to various activities that typically occur on site, there is a risk that the stored and installed ductwork will not avoid airborne contamination regardless of any measures of protection employed.” Once the initial clean has been carried out, a regular and rigorous cleaning and maintenance schedule should be put in place in order to keep standards high. Consequently, system designers should, from the very start, specify their expectations for the routine cleaning of the ductwork system and highlight the need for suitable access points that allow for quick and easy access by maintenance personnel – plus their specialist cleaning equipment. By taking these needs into account and


employing a specialist cleaning contractor from the very outset, a precise number of cleaning access panels can be determined and fitted and the contractor can verify the practical access requirements for future cleaning and maintenance operations, identifying potential issues that could disrupt the scheduled upkeep further down the line.


Kitchen aid Cleaning kitchen ductwork not only keeps the system contaminant-free but it also goes a


long way in reducing the risk of fire caused by a build-up of grease and oil. The careful placement of access panels is


once again a key consideration, particularly in kitchens where space is at a premium. 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. Furthermore, it is a legal obligation 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’. In kitchen environments, filter systems are


often used to protect the fan and will need to 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. A number of different tests can be used as part of the kitchen ductwork maintenance, including wet film thickness tests (WFTT) for grease and deposit thickness tests (DTT) for harder, carbonised deposits. All tests, measurement locations and cleaning methods are listed in the TR19 document and


certain insurance companies will only offer insurance to companies that have a certificate of cleanliness that proves their kitchen ductwork has been cleaned in line with the recommendations contained within. Following a full kitchen ductwork clean, a verification report is often required to document the pre and post clean measurements, details of any additional works carried out, COSHH data on chemicals used, observations on the condition of the ductwork, photographic records and recommendations on future cleaning requirements.


Keep it clean


As air moves through a ventilation system it often carries dust, dirt and other debris with it and over time this begins to build up in the ductwork, eventually resulting in pockets of mould or bacteria. These unwanted intruders then find their way into workspaces or other heavily occupied areas as air passes over them and distributes them around the building. In kitchen ductwork, the issue is complicated further by the presence of grease and oil deposits, heightening the fire risk as well as the threat of prosecution should the worst happen. Carefully planned and easily accessible ductwork alongside a robust maintenance schedule carried out by professionals can help uphold the highest standards when it comes to indoor air quality, safeguarding the wellbeing of building occupants as well as meeting legal requirements well beyond system commissioning.


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April 2020 35


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