Phoenix Journal · Extraction
The grease filter in your canopy is the first thing standing between a hot hob and a duct fire. Here is how baffle and mesh filters really compare, and which one belongs above your line.
Kitchen Extraction Cleaning
Every commercial canopy needs a grease filter, but the two common types behave very differently once the fat starts flying. One is built to shed grease and shrug off heat. The other quietly soaks it up until it becomes a problem.
The filter is the workhorse of your extraction system. It catches airborne grease before it travels into the ductwork, so the choice between a baffle filter and a mesh filter is not a detail - it decides how much grease ends up coating your ducts, how hard your fan has to pull, and how a small flare-up on the hob behaves. Get it right and the rest of the system has an easier life. Get it wrong and you are building a fire risk one shift at a time. Here is how the two compare, and why the commercial standard has settled firmly on one of them.
A baffle filter is a solid unit of interlocking stainless steel vanes. Grease-laden air is drawn off the hob and into the filter, where those vanes force it to change direction sharply, several times over, in the space of a few centimetres. Air is light and follows the turns easily. Grease droplets are heavier and carry more momentum, so they cannot follow the rapid changes of direction. They strike the metal, condense on the cool stainless surface, and run down into a collection trough at the base of the filter rather than carrying on into the duct.
That mechanism matters for fire. Because the baffles are made of stainless steel, they are non-combustible - heat and grease do not damage them, and they will not carry a flame from a hob flare-up up into the ductwork. They drain grease away instead of holding it in the airstream. This is why DW/172, the UK specification for kitchen ventilation systems, points to baffle-style filters as the primary grease filter for a commercial canopy: high grease-removal efficiency, easy to clean, and a genuine measure of flame protection. In practice, baffles are the commercial standard, and a modern stainless canopy is built around them.
A mesh filter is a frame packed with layers of crimped metal mesh. Instead of using momentum to fling grease out of the airstream, it relies on sheer surface area - the air threads through the mesh and grease clings to the wires. When the filter is clean and the kitchen is light on grease, that works reasonably well and offers very little resistance to airflow. The trouble starts as soon as it loads up.
Mesh clogs quickly, especially in a busy commercial kitchen. As the layers fill with grease the filter stops draining and starts holding - and a grease-soaked mesh pad has two failure modes. It drips warm grease back down onto the hob, and it effectively becomes fuel sitting directly over an open flame. That is the core reason mesh is treated as a fire risk in commercial extraction: a saturated pad can carry a flare-up straight into the material of the filter. On top of that, a clogged mesh filter chokes the airflow it was prized for and lets more grease slip past into the ductwork, which is exactly the grease that later shows up on a canopy cleaning fire risk assessment as a hazard.
For any canopy sitting over a genuine cooking line, the baffle filter is the right answer - it is what the standard expects, it drains grease instead of hoarding it, and it will not turn a small flare-up into a duct fire. Mesh earns its place only in light-duty spots or as a second stage behind a baffle. Whichever you run, the filter is the start of the job and not the end of it: grease that slips past still settles in the ducting, which is why how often you clean the extraction system matters just as much as what you hang in the canopy.
Questions
Sometimes, but check the airflow first. Baffle filters offer more resistance to airflow than mesh, so dropping them into a canopy and fan that were sized for mesh can reduce extraction and overwork the fan. If your system was designed around mesh, have the airflow assessed before you switch rather than assuming the slots are a straight fit.
No. A good baffle filter captures a lot of grease at the canopy, but no filter removes it all - some always carries into the ducts and settles there over time. That build-up is a fire hazard and is what a TR19 Grease clean is designed to remove, so regular cleaning of the full system is still essential.
Frequently, and more often than most people expect. In a busy kitchen filters should be washed down daily to weekly depending on the volume and type of cooking, with the baffle drainage trough emptied as part of that routine. A clogged filter loses efficiency and becomes a fire risk regardless of type.
Phoenix Duct Clean · by the numbers
The right canopy and filters only help if the system stays clean. Phoenix degreases canopies, filters and ductwork to TR19 Grease - UK-wide, overnight.