Phoenix Journal · Ductwork
A hospital kitchen runs almost without pause, feeding wards where the people nearby are already unwell. That places its extraction system under a tougher standard than ordinary catering, answering to both fire safety and infection control.
Healthcare catering
A hospital kitchen never really stops, and that is precisely why its extraction system deserves closer scrutiny than almost any other you will find.
Feeding wards around the clock means the canopies, filters and ductwork above the ranges rarely get the quiet, empty night that a restaurant relies on for a deep clean. Meals go out in large volumes, seven days a week, and the grease and particulate that carries into the extract keeps building whether or not anyone has booked the system in. Layer onto that a simple, uncomfortable fact - the people a few walls away are already unwell - and you begin to see why hospital extraction is treated as an infection control matter and not just a housekeeping one.
The extract system is doing two jobs at once. It is pulling heat, steam and airborne grease away from the cooking line so the kitchen stays workable, and it is part of the wider ventilation picture that keeps contaminated air from drifting toward clinical spaces. When it is clean and balanced, it protects staff, patients and the building. When it is neglected, it quietly becomes a fire risk, a hygiene risk and an energy drain all at once. This page sets out what a well-run hospital extraction regime actually looks like, and the standards it has to answer to.
Most catering extraction in the UK is judged against TR19 Grease, the specification published by the Building Engineering Services Association (BESA) that governs fire risk management of grease accumulation in kitchen extract systems. It is the document your insurer, your fire risk assessor and any competent cleaning contractor will reach for. It sets a clear, measurable target - grease deposits controlled to an average of 50 microns or below after cleaning, confirmed by a Deposit Thickness Test for hardened, carbonised residue or a Wet Film Thickness Test for softer grease. Fifty microns is barely more than the thickness of a sheet of paper, which tells you how little build-up it takes before a system is considered a hazard.
A hospital, though, sits inside a second rulebook as well. Ventilation across healthcare premises is shaped by HTM 03-01, the Department of Health and Social Care’s technical memorandum for specialised ventilation, which sets expectations for air change rates, filtration, pressure relationships and - importantly - routine inspection and validation. Kitchen extract is not an operating theatre, but it does not exist in isolation from the estate’s wider ventilation strategy. The practical result is that a hospital extraction system has to satisfy the fire-focused discipline of TR19 Grease and the hygiene-and-verification culture of HTM 03-01 at the same time, and it needs paperwork that stands up to both.
In an ordinary kitchen, the argument for cleaning the extract is mostly about fire. In a hospital it is that plus something more. Adequate, well-maintained ventilation dilutes and removes airborne particles, and a fouled extract that is not moving air as it should undermines that protection at the very point where the building can least afford it. A canopy that is not drawing properly lets steam, cooking odours and airborne grease linger and spread, and in a setting where catering sits close to wards, day rooms and circulation routes, that drift is not a comfort issue - it is a contamination pathway.
The continuous nature of the work is the hardest part to manage. Because the kitchen cannot simply close, deep cleaning has to be planned around service, often overnight or in tightly agreed windows, with the system fully isolated and the work evidenced afterwards. Grease-laden filters, internal duct surfaces and the fan itself all need to be reached, which is why adequate access panels matter so much. Extract ductwork in a hospital often runs above false ceilings, through plant rooms or up external risers, and without enough correctly placed hatches, an honest inspection is impossible and a proper clean cannot be verified. Any contractor who cannot show you before-and-after readings, photographs at each access point and a post-clean certificate has not really done the job to standard. This is the same evidence-led discipline that runs through good infection control in healthcare catering more broadly, where what you can prove matters as much as what you have done.
There is a competence dimension too. TR19 Grease sets minimum qualifications for the people doing the work, with technicians expected to hold the BESA Grease Hygiene Technician qualification. In a hospital, where the tolerance for a mistake is lower and the surrounding environment more sensitive, using accredited, qualified operatives is not a nice-to-have. It is how you demonstrate that the system serving your patients’ food is being maintained by people who understand both the fire standard and the setting they are working in.
The right cleaning frequency is not a fixed number - it follows the hours the kitchen runs and the kind of cooking it does. A hospital catering line producing hundreds of meals a day, often with heavy frying and grilling, sits firmly in the higher-risk band and needs more frequent inspection and cleaning than a lightly used staff canteen. TR19 Grease works on exactly this logic, matching intervals to usage rather than the calendar, so the honest first step is a survey that establishes how quickly your particular system fouls and where the build-up concentrates. From there you set a schedule you can defend to a fire risk assessor and an infection prevention team alike.
Keeping the system clean pays back in ways beyond compliance. A grease-choked duct forces the extract fan to work harder to move the same volume of air, drawing more power and wearing components faster, so a neglected system quietly inflates running costs across the estate. If your organisation is already trying to benchmark its kitchens’ energy use against peers, a well-maintained extract is part of that picture - clean ductwork and a properly balanced fan simply move air more efficiently. The same discipline that protects against fire and contamination also protects the budget, which is a rare alignment worth leaning on when you are making the case internally.
Compliance ultimately sits under the Regulatory Reform (Fire Safety) Order 2005 and the Health and Safety at Work Act 1974, both of which place a duty on the responsible person to manage the risk that a fouled extract represents. In a hospital that responsible person is answering not only to those laws but to the trust’s own infection prevention standards and the expectations of its regulators. A documented, verified, appropriately frequent cleaning regime is the single clearest way to show all of them that the risk is under control.
Questions
There is no single legal interval - TR19 Grease sets frequency according to how heavily the system is used. A hospital kitchen cooking large volumes seven days a week, often with heavy frying, falls into the higher-risk category and typically needs inspection and cleaning several times a year. The correct schedule should be set by a survey of your actual system and then reviewed as usage changes.
TR19 Grease is the BESA specification that manages fire risk from grease build-up in kitchen extract systems, setting a post-clean verification limit of 50 microns. HTM 03-01 is the healthcare ventilation memorandum covering how ventilation across a hospital is designed, maintained and validated. A hospital kitchen has to satisfy the fire discipline of the first and the inspection-and-hygiene culture of the second at the same time.
A poorly maintained extract that is not drawing air properly lets steam, odours and airborne grease linger and drift toward clinical areas, where patients are already unwell. Well-maintained ventilation helps dilute and remove airborne particles, so keeping the extract clean and balanced protects the wider building, not just the kitchen. That is why hospital extraction is documented and verified to a higher standard than ordinary catering.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.