TR19® Grease is BESA's specification for managing fire risk from grease accumulation in commercial kitchen extraction systems. It covers inspection, cleaning and evidence across the extract route. It should not be reduced to a generic “annual clean”: frequency should reflect use, grease loading, inspection results and risk.
Why grease inside the extract matters
Cooking aerosols that pass the canopy filters can deposit on:
- canopy plenums;
- duct walls;
- access panels;
- bends and horizontal runs;
- attenuators and treatment equipment;
- fan casings and impellers;
- discharge components.
Accumulated grease can increase fire load, restrict airflow, unbalance fans, create odour and make future cleaning more difficult.
The system can look clean from the canopy while concealed horizontal ductwork remains heavily contaminated.
What TR19 Grease is
BESA describes TR19 Grease as the definitive specification for managing fire risk associated with grease accumulation in commercial kitchen extraction systems. It is intended for new builds, upgrades and maintenance projects.
It supports a consistent approach to:
- inspection;
- assessment of contamination;
- defining cleaning requirements;
- cleaning the complete system;
- reporting and evidence;
- managing inaccessible areas and defects;
- setting an appropriate future regime.
Use the current paid specification for technical requirements. Do not rely on an old copied frequency table or a cleaning certificate with no condition evidence.
How often should kitchen extract ductwork be cleaned?
There is no responsible one-frequency answer for every kitchen.
Consider:
- cooking method and grease production;
- daily operating hours;
- number of cooking days;
- appliance and canopy performance;
- filter type and cleaning;
- historic contamination rates;
- measured/observed condition;
- changes in menu or throughput;
- insurer, landlord and fire-risk requirements.
Set an initial inspection/cleaning regime from competent advice, then adjust it using actual findings. High-volume frying may need substantially more attention than light, occasional cooking.
The whole system must be considered
A complete scope can extend from the canopy through:
- filters and plenum;
- horizontal and vertical ductwork;
- branches and risers;
- fans;
- attenuators or treatment devices where cleanable and within scope;
- terminal/discharge components.
The contractor should identify anything excluded and why. “Canopy clean” must not be confused with full extract-system cleaning.
Access panels are a design issue
Cleaning quality is limited by physical access. Problems include:
- access panels omitted at changes of direction;
- panels hidden above fixed ceilings;
- kitchen equipment blocking access;
- fire-rated enclosures with no coordinated access solution;
- landlord areas that the tenant cannot enter;
- unsafe roof routes;
- fans without service clearance;
- odour equipment installed without removal space.
The ventilation and fire design should provide access while maintaining the required system performance. Cutting uncontrolled holes into ductwork or fire-rated enclosures after completion can create new defects.
What a useful cleaning report should contain
Ask for a report that identifies:
- premises and system served;
- date and contractor;
- cooking/operating information used;
- system schematic or clear route description;
- sections inspected and cleaned;
- condition before and after;
- photographs tied to identifiable locations;
- assessment or measurements taken using the current method;
- inaccessible or excluded sections;
- damaged seals, access panels, fans or ductwork;
- residual contamination or limitations;
- recommended next inspection/cleaning date and its basis;
- actions for the operator, landlord or ventilation contractor.
A certificate with no route, scope or evidence may be difficult to defend after an incident.
Daily filter cleaning is not duct cleaning
Operators should routinely clean canopy surfaces and removable grease filters according to the system and manufacturer requirements. That reduces loading but does not prove the duct is clean.
Filters can also fail when:
- installed in the wrong orientation;
- missing or replaced with an unsuitable type;
- air bypasses the frame;
- loaded beyond their effective condition;
- washed in a way that damages them;
- returned wet or incomplete.
Include filter condition in routine checks.
Interaction with odour-control equipment
ESPs, carbon filters and UV/ozone equipment each need their own maintenance. Grease contamination can reduce performance or create hazards downstream.
Coordinate the extract-cleaning contractor with the equipment supplier. Confirm:
- which components can be cleaned and by what method;
- electrical isolation and safe access;
- whether cells, lamps or media require specialist service;
- how pressure drop and airflow are checked afterwards;
- what waste handling applies;
- how warranties are protected.
When the cookline changes
Review the cleaning regime after:
- adding fryers, chargrills or woks;
- changing to solid fuel;
- increasing operating hours;
- increasing production;
- altering filters or treatment equipment;
- changing fan speed;
- extending ductwork;
- recording unusually fast grease accumulation.
The old schedule was based on the old duty.
Records belong in the handover and operating system
Keep:
- as-installed drawings;
- access-panel schedule;
- commissioning results;
- prior cleaning reports;
- filter-cleaning records;
- equipment service reports;
- fire-risk assessment actions;
- planning-condition maintenance records;
- menu/equipment changes;
- correspondence about inaccessible sections.
The KIG 318 Commercial Kitchen Installation Checklist helps teams ensure access, maintenance and handover evidence are considered before the system disappears behind ceilings and enclosures.
Related reading
Sources and further reading
This is general fire-risk and maintenance information, not a cleaning specification or insurer instruction. Use current TR19 Grease, competent contractors and the requirements applying to the premises. Last reviewed: 13 August 2026.