Phoenix Journal · Extraction
Grease dripping from a commercial kitchen canopy is a clear signal that build-up has passed the level the system can safely manage. Here is what causes it, why it matters for fire safety, and how to put it right.
If grease is dripping from your canopy, the extraction system is telling you something has gone past the point it can quietly cope with.
It rarely happens overnight. Grease-laden vapour rises off the range, hits the cold metal of the canopy and the baffle filters, and condenses into a sticky film. Under normal conditions that film drains down into the collection trough, or stays thin enough to sit harmlessly in place until the next clean. When you start seeing amber droplets forming on the underside of the canopy, running down the joints, or spotting the hotplate below, the balance has tipped. More grease is arriving and settling than the filters and drainage can carry away.
The good news is that dripping is a symptom with a short list of causes, and none of them are mysterious. Below we walk through what is actually happening inside the canopy, why it matters for fire safety and hygiene, and what a proper response looks like - so you can tell the difference between a quick filter fix and a system that needs a deep clean back through the ductwork.
What the numbers mean
The UK benchmark for grease in a kitchen extract system is set out in TR19 ® Grease, the specification published by the Building Engineering Services Association. It says grease should be controlled so the deposit does not exceed a mean average of 200 microns between scheduled cleans. That is a genuinely thin layer - roughly half the thickness of a business card - which tells you how little grease it takes for a system to be considered due for attention.
Contractors verify this with a Deposit Thickness Test, taking readings at points along the canopy plenum and ductwork. Under 200 microns is regarded as an acceptable, well-maintained level. Between 200 and 999 microns the system needs cleaning. At 1,000 microns or more it is rated a high fire risk and immediate cleaning is recommended, with any spot reading over 500 microns flagged for prompt attention. If grease is already visibly dripping from your canopy, you are almost certainly well beyond the 200 micron mark in at least one part of the system, and often much higher deep inside where you cannot see it.
The canopy is designed to catch and manage grease, not to be grease-free. Air pulled off the cooking line carries a fine aerosol of fat and oil. The baffle filters force that air to change direction several times, and the heavier grease particles are thrown out of the stream, coating the baffles and draining down through the drain slots into a trough or removable cup. Dripping means one or more stages of that process has stopped working. In practice it usually comes down to a handful of causes.
Reading the drip tells you where to look. A drip from the filter face points at the filters and trough. Staining that seeps from the seams, corners or where the canopy meets the ceiling points at the plenum and the ductwork behind it - and that is the part you cannot fix with a cloth and a bucket.
Dripping grease is not just untidy. Everything settling in and running out of that canopy is combustible, and it sits directly above open flames and hot surfaces. This is precisely the risk TR19 ® Grease exists to manage, and why keeping the system clean is bound up with your duties under the Regulatory Reform (Fire Safety) Order 2005. A layer of grease inside the canopy and duct is fuel; a stray flare-up on the range is the ignition source. Once a grease fire takes hold in the plenum it can travel through the ductwork surprisingly fast, carrying flame into ceiling voids and other parts of the building.
There is a hygiene and safety cost too. Grease dripping onto the hotplate contaminates food and surfaces and gives an environmental health officer an obvious, visible sign that the system is not being maintained. Droplets on the floor around the line are a genuine slip hazard for a busy team. And grease that escapes into the ceiling cavity soaks into insulation, plasterboard and electrical wiring, turning a cleaning job into a repair bill.
There is also the quieter question of your insurance. Many commercial policies require the extract system to be cleaned to a recognised standard and expect you to keep records - the post-clean report, before-and-after photographs and the deposit readings. If a fire starts in a neglected, grease-laden system, a missing cleaning history can put a claim at risk. A visible drip is a warning worth heeding before it becomes any of those problems.
The practical fix depends on what the drip is telling you. If it is purely the filters and trough, tightening up your in-house cleaning routine may be enough. If grease is coming from the plenum and the joints, the system needs a professional deep clean that opens up access panels, degreases the plenum and works back along the ductwork to the fan - then measures the result against the 200 micron benchmark and documents it. The honest way to know which one you are dealing with is a proper inspection. If you are unsure how frequently your system should be cleaned in the first place, that depends heavily on cooking volume and the type of food, and it is worth reading up on how often to clean a kitchen extraction system and on how kitchen grease contributes to fire risk so the schedule matches the way you actually cook.
Questions
Yes. The grease running out of the canopy is combustible and it sits directly above open flames and hot surfaces, so it acts as fuel for a flare-up. If a fire takes hold in the grease-laden plenum it can travel quickly through the ductwork into ceiling voids. Visible dripping almost always means the deposit is well beyond the 200 micron level that TR19 Grease treats as acceptable.
Sometimes, but not always. If the grease is only coming from saturated filters and a full drainage trough, degreasing the filters regularly and emptying the collection cup may resolve it. If grease is seeping from the seams, corners or where the canopy meets the ceiling, the source is the plenum and ductwork behind the filters, which needs a professional deep clean rather than a surface wipe.
TR19 Grease is the UK specification for cleaning kitchen extract systems, published by the Building Engineering Services Association. It says grease should be controlled so the deposit does not exceed a mean average of 200 microns between scheduled cleans - roughly half the thickness of a business card. Contractors measure it with a Deposit Thickness Test, and readings of 1,000 microns or more are rated a high fire risk.
The responsible person for the premises, usually the business owner or manager, has a duty under the Regulatory Reform (Fire Safety) Order 2005 to manage fire risk, and that includes the extract system. In practice this means arranging regular cleaning to a recognised standard and keeping the records, such as the post-clean report, photographs and deposit readings, to show the system has been maintained.
Phoenix Duct Clean · by the numbers
The right kit only helps if the system stays clean. Phoenix degreases canopies, filters and ductwork to TR19 Grease - UK-wide, overnight.