Phoenix Journal · Ductwork
Most kitchens still service their ventilation by the calendar, then scramble when a fan seizes mid-service. Predictive maintenance watches the system's real condition instead, so you act before a failure - or a fire risk - ever reaches the floor.
Maintenance strategy
There are two honest ways to look after a commercial kitchen ventilation system - service it on a fixed schedule, or watch its actual condition and act the moment the numbers move.
Both approaches have their place, and the right answer for your site usually blends them. The old default is planned preventive maintenance - book the extract clean and the fan service at set intervals, whatever the system is actually doing in between. Predictive maintenance flips that logic. Instead of trusting the calendar, you measure real conditions - grease build-up, fan vibration, motor current, pressure across the filters - and let the data tell you when a component is drifting towards failure or a duct is drifting towards a fire risk.
This matters more in a kitchen than almost anywhere else, because your ductwork carries two risks at once. There is the mechanical risk of a fan or motor packing up mid-service, and there is the fire risk of grease coating the inside of the duct. The industry benchmark for the second is BESA's TR19® Grease specification, which is now the reference point insurers and fire risk assessors expect you to work to under the Regulatory Reform (Fire Safety) Order 2005. TR19® Grease sets a clear line: grease should not exceed a mean average of 200 microns of build-up between cleans - roughly half the thickness of a business card - and a compliant clean should bring the system back below 50 microns. Predictive maintenance is really about staying the right side of numbers like these without over-servicing a clean system or ignoring a dirty one.
Planned preventive maintenance - often called PPM or time-based servicing - means fixing your intervals in advance and sticking to them. TR19® Grease gives sensible starting frequencies tied to how hard the kitchen works: heavy use of 12 to 16 hours a day points to a deep clean roughly every three months, moderate use of 6 to 12 hours a day to every six months, and light use to around every twelve. Fan belts, bearings and filters get serviced on their own rolling schedule alongside.
Predictive maintenance - closely related to condition-based maintenance - keeps the system under continuous or regular measurement and only triggers work when the readings say so. In a kitchen extract system that usually means a small set of sensors on the fan and in the duct: vibration monitoring to catch bearing wear and imbalance early, motor current and temperature to flag a struggling drive, differential pressure across the filters to show loading, and sometimes CO₂ or airflow sensing to confirm the system is actually shifting the air it should. Grease build-up is still verified against TR19® Grease using deposit thickness tests, but the timing of the clean is guided by evidence rather than a fixed date.
Whichever route you take, the same thresholds govern whether your kitchen is safe and compliant. Predictive maintenance simply gives you earlier, sharper sight of them - and where a duct also serves life-safety functions, the case for monitoring gets stronger still, as we cover in how smoke control and ventilation interact.
Read together, these tell the whole story: 200 microns is the line you must not cross between cleans, three months is how fast a busy kitchen tends to reach it, and 50 microns is proof the job was done properly. Planned maintenance aims to land inside those figures by guesswork and experience; predictive maintenance measures its way there. For most operators the sweet spot is a planned baseline - a booked deep clean at a sensible TR19® frequency - with condition monitoring layered on top to catch the surprises the calendar never could.
Questions
No. Predictive maintenance tells you when and where grease and mechanical problems are building up, but it does not remove the deposits. You still need a physical deep clean that scrapes and washes the ductwork back to a mean below 50 microns to meet TR19® Grease. Think of monitoring as the early-warning system and the clean as the fix.
The common measurements are fan vibration to spot bearing wear and imbalance, motor current and temperature to flag a struggling drive, and differential pressure across filters to show how loaded they are. Some sites add airflow or CO₂ sensing to confirm the system is moving the air it should. Together these trends warn you a component is failing, often weeks before it actually stops.
It depends on how much a breakdown or a failed fire risk inspection would cost you. A small single-fan kitchen may be served perfectly well by a sensible planned interval and a good post-clean report. Higher-risk or high-volume sites, where an unplanned shutdown means lost covers and an emergency call-out, tend to recover the cost of monitoring quickly by avoiding those surprises.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.