The Building Engineering Services Association (BESA) TR19 regulations set out best practice for cleaning ventilation ductwork and kitchen extract flues. TR19 was developed in 1988, in order to “provide a safe working environment for staff; reduce fire risks; and avoid contamination of food preparation areas”. It has become the standard to adhere to when performing ductwork cleaning operations.
TR19 guidelines lays out best practice with regard to access to ductwork, inspection of ductwork, cleaning processes and post-cleaning checks.
The guidelines state that the system must contain enough access panels of sufficient size to enable regular inspection and cleaning.
The panels should be made of the same material as the ductwork and should include insulation, seals (to prevent leaks) and quick-release catches.
The recommendation is that panels are located at the top or along the side of the ductwork. Panels that have to be fitted on the underside but be sealed properly to ensure they don’t leak.
Inspection of ductwork must be carried out at regular intervals to establish whether it needs cleaning. The Wet Film Thickness Test (WFTT) assesses the level of build-up of grease and soft deposits and the Deposit Thickness Test (DTT) will gauge the extent of build-up of carbonised deposits. Inspections must be carried out at least every 12 months, with more frequent inspections to give a more accurate assessment of the required cleaning frequency. TR19 details the locations in the ductwork where the measurements of deposits should be taken. One state-of-the-art inspection method is by means of a camera probe. This allows engineers to see deep into the ductwork to confirm both the extent of the build-up and the type of cleaning process required.
TR19 outlines a number of cleaning methods, including hand wiping, hand scraping, chemicals, high pressure water wash, steam cleaning, rotary brush etc. Not all methods are appropriate for every type of ductwork and location.
The TR19 guidelines state the recommended intervals between cleans. The cleaning intervals for kitchen extract flues are dependent on the cooking methods used and the volume of airborne grease contaminants.
As grease in kitchen extraction systems is a well-known fire hazard, a new specification (TR19 Grease) was published in July 2019. TR19 Grease was developed to increase the level of compliance with regard to fire safety cleaning.
Although cleaning frequency is established by regular inspections, the minimum cleaning frequency recommendation is as follows:
Post Cleaning Verification
A visual inspection of ductwork and flues is carried out after cleaning. Deposits must not exceed .05 mm in thickness. A Post Cleaning Verification Report must then be provided detailing the systems that have been cleaned, photographic records, COSHH data on any chemicals used, observations on the condition of the ductwork etc.
HVDS engineers clean metal and fabric ducting and kitchen extraction flues to TR19 standards. They are also BESA Air Hygiene Operative (AHO) accredited. The course assesses their competency in working safely, the principles of ventilation ductwork, preparing the work location, cleaning ductwork systems, working sustainably and communication and behaviour in the workplace.