TR19 Grease is the standard for keeping grease in kitchen extract systems under control. It was written by BESA, the building services trade body, in 2019. It says how often to clean, based on how many hours a day you cook: every 3, 6 or 12 months.
How often to clean
| Cooking per day | Clean the ducts every |
|---|---|
| 12 to 16 hours (heavy use) | 3 months |
| 6 to 12 hours (moderate use) | 6 months |
| 2 to 6 hours (light use) | 12 months |
Sources: BESA, Kent Fire and Rescue
These are the minimum. You may need cleaning more often if:
- You do a lot of frying, or cook over wood or charcoal. (Kent Fire and Rescue)
- A risk assessment by a competent person says so. (BESA)
- Your insurer sets its own dates. Check your policy.
Hoods and filters need cleaning much more often: daily, or as the maker says. (Kent Fire and Rescue)
How much grease is too much
TR19 Grease sets two limits for grease inside the ducts (BESA):
| Grease thickness | What it means |
|---|---|
| Under 200 microns on average | The limit between cleans |
| 500 microns or more | Clean that spot straight away |
A micron is a thousandth of a millimetre. So 200 microns is a fifth of a millimetre: thinner than it sounds, which is why it builds up unseen.
How grease is measured
The cleaner measures the grease before and after the clean with one of two tests (BESA):
- Wet Film Thickness Test (WFTT)
- Deposit Thickness Test (DTT)
Both give a thickness in microns, so you can check it against the limits above.
The readings go in your post-clean report, with photos. See the TR19 certificate guide.
What the whole system means
TR19 Grease covers the whole extract system, from the canopy to where the duct leaves the building. (AXA) Cleaning only the canopy and filters isn't enough.
Is your clean due?
We clean kitchen extract systems across Bristol to TR19 Grease. See kitchen extract cleaning in Bristol.
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