Phoenix Journal · Extraction
Wok and tandoor cooking loads a canopy and duct with grease and carbon faster than almost anything else on the range. Here is how to keep that extract system capturing properly, cleaned to standard and provably compliant.
Kitchen Extraction Cleaning
Wok and tandoor lines are the hardest working part of any extract system, and they punish canopies, filters and ductwork faster than almost anything else on the range.
A wok burner throws out a searing, fast-moving plume of oil vapour and steam; a tandoor adds fierce charcoal or gas heat, carbon soot and the sticky residue of marinades hitting hot clay. Put the two together in a busy service and you generate a grease and carbon load that a general-purpose canopy was never sized to hold. The result, left unmanaged, is grease creeping deep into the duct run, a fan that slows as its impeller loads up, and a fire risk that quietly grows with every shift.
Getting extraction right over these appliances is partly a design question and partly a cleaning discipline. The two standards that matter in the UK are BESA's DW172, which covers how the ventilation system should be designed and built, and TR19 Grease, which sets how the extract system should be cleaned, measured and verified. Below is the process we work through when we survey, clean and certify an extract system that sits over wok and tandoor cooking.
The demand starts at the canopy face. DW172 sets a capture velocity for each type of appliance so the plume is actually drawn in rather than rolling out into the kitchen. Light loads such as steamers and boiling pans need about 0.25 m/s, medium loads such as fryers and open ranges around 0.35 m/s, and heavy loads - intense frying and live-flame grilling of the kind wok and tandoor cooking produces - up to 0.5 m/s. Multiply that velocity by the canopy area and you get the volume of air the system must move. Under-size it, or let it clog, and capture fails: grease and steam spill into the room and settle on surfaces that should never see them.
Volume is only half the story, though. Grease-laden air has to keep moving quickly enough through the duct that it does not drop out and stick to the walls. High-grease wok kitchens can need well over 50 air changes an hour to hold that capture and keep the air velocity up, which is far beyond a typical light-cooking site. When a kitchen evolves - a tandoor and extra fryers added to what began as a modest range - the cooking capacity can double while the canopy and duct stay exactly as they were, and the extraction quietly becomes undersized. That is one of the most common problems we find on Asian and Indian kitchen sites.
Design detail helps here. Where a kitchen runs genuinely different cooking types side by side, separating the heavy wok and tandoor line onto its own canopy and duct - rather than sharing a single system across the whole kitchen - keeps the fierce grease and carbon load contained and easier to clean. If you are planning a refit or trying to fix a struggling system, it is worth thinking about zoning the kitchen by cooking type so the demanding appliances are grouped and extracted as a unit. It makes the airflow calculation honest and the cleaning far more effective.
Some canopies over high-heat lines also run a cold water mist across the plume. As the hot grease vapour meets the mist it cools, solidifies and grows into larger droplets that are captured before they reach the duct - a genuine help over wok burners, though it does not remove the need to clean the run behind it.
Frequency is where wok and tandoor sites most often fall short. TR19 Grease ties cleaning intervals to how many hours a day the system runs: heavy use of 12 to 16 hours a day calls for a clean every 3 months, moderate use of 6 to 12 hours every 6 months, and light use every 12 months. Because these appliances generate so much grease per hour, a busy wok and tandoor kitchen usually sits firmly in the heavy-use band and needs quarterly attention as a floor, not a ceiling - your measured grease readings may push it shorter still.
Doing this well protects three things at once: fire safety, because grease is the fuel that turns a flare-up into a duct fire; your insurance position, since most policies now expect documented TR19 compliance and a valid verification report; and the working life of the system itself, because a system kept clean pulls better, runs cooler and lasts longer. The evidence trail - grease measurements, photographs and the post-clean report - is what turns a clean into proof you can hand to an insurer or an assessor without hesitation.
Questions
TR19 Grease ties the interval to daily running hours, and most wok and tandoor kitchens fall into the heavy-use band of 12 to 16 hours a day, which calls for cleaning every 3 months. Because these appliances produce so much grease per hour, quarterly should be treated as a minimum rather than a target. A wet film thickness measurement of the grease inside your duct is the proper way to confirm whether you need to clean even more often.
A wok burner throws out a fast, searing plume of oil vapour and steam, while a tandoor adds fierce heat, charcoal soot and sticky marinade residue. Together they generate a far higher grease and carbon load per hour than a typical range, and that residue bakes hard onto canopy, filter and duct surfaces. If the canopy and duct were sized for lighter cooking, or the kitchen has added appliances over time, the system becomes undersized and grease builds up deeper into the run.
After cleaning we re-measure the grease film using a wet film thickness test, and a compliant clean leaves under 50 microns - roughly half the width of a human hair. We record before and after photographs along the whole duct route and issue a post-clean verification report. That report is the document your insurer and fire risk assessor will expect to see as evidence of TR19 Grease compliance.
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.