Phoenix Journal · Ductwork
Planned preventive maintenance is a documented cycle of inspection, cleaning, testing and record-keeping - not a calendar reminder. Here is what it actually involves, and why the kitchen extract sits at the sharp end of it.
Planned preventive maintenance
Planned preventive maintenance is the difference between finding a problem on a quiet Tuesday and finding it when a fan seizes mid-service - or worse, when a grease fire takes hold in a duct nobody had opened in two years.
The phrase gets used loosely. To some it means a reminder in a calendar; to others it is a folder of certificates produced once a year for the insurer. Done properly, planned preventive maintenance (often shortened to PPM) is a structured, documented cycle of inspection, cleaning, testing and record-keeping that keeps a system safe, compliant and running - and that quietly heads off the expensive failures before they happen. For anyone responsible for a commercial kitchen, the extract and ductwork sit right at the sharp end of that cycle, because a neglected grease-laden duct is both a fire risk and, increasingly, a reason for an insurer to decline a claim.
This piece walks through what PPM actually involves in practice - the tasks, the standards behind them, the intervals, and the paperwork that proves it all happened. It is written for the person who has to sign off the schedule, not the person selling it.
Reactive maintenance is what most sites drift into by default: something breaks, someone calls it in, an engineer attends. It feels cheaper because you only spend when you have to. In reality it is the costliest way to run anything, because failures rarely pick a convenient moment and the damage has usually spread by the time you notice. Planned preventive maintenance flips that logic. Instead of waiting for a fault, you carry out a defined set of tasks at set intervals so that wear is caught early, consumables are replaced on schedule, and the system spends far less of its life broken.
In the UK the backbone of most credible PPM programmes is SFG20, the industry-standard maintenance specification first published by the Building Engineering Services Association (BESA) in 1990. SFG20 holds more than 1,500 maintenance schedules, updated with around 700 changes a year, each one setting out the individual tasks for a given asset, how often each task should be done, and the skill level the engineer needs. It also carries a criticality colour code - red for statutory and legal tasks, pink for mandatory or business-critical, amber for optimal and green for discretionary - so you can tell at a glance which jobs you simply cannot let slip. This is the framework that stops a schedule being one person's guesswork.
Whatever the asset, a proper programme rests on a few things being in place. Miss any one of them and the schedule becomes decorative rather than useful:
That last point matters more than people expect. When something goes wrong, the question is never only "was it maintained?" but "can you prove it?" A plan with no evidence behind it is, for practical purposes, no plan at all.
The kitchen extract, by the numbers
Nowhere is planned maintenance more clearly load-bearing than a commercial kitchen extract system. The governing standard here is BESA’s TR19® Grease, which sets grease limits, cleaning methods and the verification you need to keep. These are the figures that shape the schedule.
Those intervals are not arbitrary. A kitchen turning out fried and chargrilled food lays down grease far faster than one that mostly bakes or boils, so the schedule follows the cooking, not the calendar alone. Inspection intervals under TR19® should never exceed twelve months, whatever the cooking style.
Strip away the jargon and a planned extract clean runs to a recognisable sequence. First an inspection to establish how much grease has built up and where, measured with a Deposit Thickness Test (DTT) or Wet Film Thickness Test, taken at points along the run rather than guessed at. If readings are approaching that 200-micron mean, the system is due. The clean itself has to reach the whole internal surface - the canopy and filters, the fan, and critically the full length of ductwork between them, which is where grease quietly accumulates out of sight.
Reaching all of it depends on access. TR19® Grease expects access panels along the ductwork at regular intervals and at every change of direction, because a bend you cannot open is a bend you cannot prove is clean. On older systems, part of a first planned visit is often identifying where access is missing and fitting compliant panels so the system can actually be maintained on every cycle thereafter. It is unglamorous work, but without it the rest is theatre.
The tangible output of a compliant clean is the post-clean verification report, and it is worth knowing what a good one contains, because this is the document your insurer and fire risk assessment lean on. It should include before-and-after photographs taken from matching positions, DTT or Wet Film Thickness readings confirming grease is back below the threshold, a written summary of the work, notes on any areas that could not be reached, system drawings marking what was cleaned, and a hygiene certificate naming the technician, the date and the location. Loose photos with no readings and no named engineer will not stand up to scrutiny after a fire - the report has to demonstrate the standard was met, not merely that someone attended.
Keep those reports in an unbroken run. A single certificate proves one visit; a sequence proves a regime. The Regulatory Reform (Fire Safety) Order 2005 and the Health & Safety at Work Act 1974 both put the onus on you to control the risk and show you are controlling it, and a continuous record is how you show it. The same discipline that governs the kitchen extract applies across the wider estate - the same asset register, intervals and evidence trail that underpin planned preventive maintenance for building services generally. And where you run several kitchens, the logic scales: bringing them onto one schedule is exactly the aim of planning preventive maintenance across a multi-site kitchen estate, so no single site slips through unseen.
Questions
Reactive maintenance means waiting for something to break and then fixing it, which tends to be the most expensive approach because failures rarely happen at a convenient time and the damage has usually spread by the time you notice. Planned preventive maintenance carries out defined tasks at set intervals so wear is caught early and consumables are replaced on schedule. The result is far less unplanned downtime and, crucially, a documented trail proving the work was done.
BESA's TR19 Grease standard ties frequency to how hard the kitchen works. Heavy use of 12 to 16 hours a day points to quarterly cleaning, moderate use of 6 to 12 hours to roughly six-monthly, and light use of 2 to 6 hours to annually. The underlying rule is that the mean grease deposit must not exceed 200 microns between cleans, so kitchens producing a lot of fried or chargrilled food often need cleaning more often than the headline interval suggests.
A compliant report should include before-and-after photographs taken from matching positions, Deposit Thickness Test or Wet Film Thickness readings confirming grease is back below the threshold, a written summary of the work, notes on any areas that could not be accessed, system drawings showing what was cleaned, and a hygiene certificate naming the technician, date and location. This is the document your insurer and fire risk assessment rely on, so loose photos with no readings will not stand up to scrutiny after a fire.
TR19 Grease is best-practice guidance rather than a law in itself, but it is the recognised way to demonstrate you are meeting legal duties under the Regulatory Reform (Fire Safety) Order 2005 and the Health and Safety at Work Act 1974. It is also widely written into UK insurance policy conditions. In practice, following TR19 and keeping the records is how a responsible person proves the grease fire risk is being controlled.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.