Job Type: Commercial Kitchen Extract Cleaning.

Site details: Main kitchen for a farmers market with onsite restaurant which uses the local market produce.

Special features: This system comprises of 2.5 metres of ductwork from the canopy to a large externally mounted fan unit.

The system operates under high grease load and temperature. Due to the varying types of cooking, this system is cleaned on a 6 monthly basis.


  1. Kitchen Extract Systems have an increased fire, odour, vermin & hygiene risk compared to general supply and extract systems. This is due to the grease build up acting as a potential ignition source, contributed by the heat in the kitchen, possibly elevated oxygen levels from a fresh air supply source and the general deposition of cooking oils on ventilation system components and the ductwork itself acting as fuel.
  2. Wet Film Thickness Tests (WFTT) were carried out at various locations throughout the system, to determine the overall level of grease deposition. Individual readings of over 50 microns are deemed unclean. An average reading across the system of 200 microns or more is deemed unclean. Any individual readings in excess of 500 microns require immediate attention. In accordance with BESA TR19, tests were carried out at the following locations (where accessible).
  3. The WFTT readings pre clean were as follows: Ductwork from canopy 800 microns, fan unit 800 microns.
  4. The work was carried out successfully by degreasing and deep cleaning the Fan unit and the internal surfaces of the associated ductwork.
  5. All areas were properly cleaned with results below 50 microns.
  6. During the cleaning works we discovered that the discharge for the extract fan unit had no collection tray. We recommended that a removable drip tray is to be installed to catch all the grease discharge and to reduce the fire risk. Continued cleaning at the recommended intervals will also be necessary.

Before & After Photos

Kitchen Extract Cleaning Case Study December 2016
Kitchen Extract Cleaning Case Study