Phoenix Journal · LEV Testing
A failed LEV test rarely means your kitchen extraction is broken overnight - it usually means airflow, filters or fabric have drifted below the numbers your system was signed off against. Here is what an examiner is really measuring, and why this year's result went the way it did.
Opening a report and seeing your extraction system marked amber or red is a horrible moment, especially when nothing about the kitchen feels different from last year.
The frustrating truth is that most LEV systems do not fail because something dramatic broke. They fail because performance has quietly drifted - a little more grease in the filters, a slightly slack fan belt, a flexible duct that has sagged and cracked - and the examiner has finally caught the system below the numbers it was originally designed and signed off to hit. Your canopy might still feel like it is pulling well from where you stand at the pass. The instruments tell a more exact story.
An LEV thorough examination and test - often shortened to TExT - is not a pass-or-fail MOT in the way people imagine. It is a measured comparison. The examiner records what your system is actually achieving at each test point today, and holds those readings against the design intent and the benchmarks in the Health and Safety Executive’s guidance. When the gap is too wide, the point is graded down. Understanding what moved, and why, is the whole game - because once you know that, the fix is usually straightforward and the next result is back in the green.
What the test is actually checking
The legal spine of all this is Regulation 9 of the Control of Substances Hazardous to Health Regulations. It requires that engineering controls like your extraction canopy are examined and tested at suitable intervals, and for most systems that interval is at least every fourteen months. The detail of how a competent examiner should carry that out sits in the HSE guidance document HSG258, which inspectors treat as the benchmark for what good LEV management looks like. Your examiner works to it, and so does the officer who might one day walk into your kitchen.
A proper examination has three strands, and a failure can come from any of them. First there is the visual and structural inspection - the examiner looks for mechanical damage, corrosion, poor joints, cracked flexible ducting and any modifications that were never part of the original design. Second there is the performance measurement - calibrated instruments read airflow, duct velocity and the capture or face velocity at the canopy, and those figures are compared against the commissioning data. Third there is the control effectiveness judgement - the honest question of whether grease, smoke and cooking contaminants are genuinely being drawn away from people rather than drifting back into the room. A system can be spotless and still fail the third test if the air simply is not moving fast enough where it matters.
The usual culprits
When we walk a failed report back to its cause, the same handful of issues come up again and again. By some distance the most common is a drop in extraction rate at the canopy face. Kitchen ductwork guidance points to face velocities in the region of 0.25 to 0.5 metres per second across the canopy, depending on how heavy the cooking duty is, and a system that has slipped below its design figure loses the ability to catch the plume at source. The air is still moving - just not fast enough to overcome the rising heat and momentum of the cooking below it.
What robs you of that velocity is rarely one big thing. It is an accumulation:
Poor extraction has a habit of announcing itself before the test ever comes round. If you have been mopping moisture off stainless steel each morning, that is often the same underlying weakness showing up early - condensation under the canopy is frequently a sign that warm, wet air is not being carried away as briskly as it should be. By the time an examiner arrives, the instruments simply confirm what the kitchen has been telling you.
Turning a red into a green
A failed result is not a fine and it is not a shutdown notice - it is a to-do list with numbers attached. The value of a good report is that it tells you exactly which test point fell short and by how much, which turns a vague worry into a specific job. In most cases the corrective work is proportionate: a thorough deep clean to strip grease from the filters, canopy and accessible ductwork, a fan service to sort belts and bearings, and reseated or replaced flexible connectors to close up the leaks. Once airflow is restored, a re-test at the same points usually brings the grades straight back up.
The one thing worth taking seriously is the gap in between. If a system has been graded down for control effectiveness, it may not be adequately protecting people until it is put right, and depending on the severity you may need to lean on other measures in the meantime. That is why the sensible pattern is to keep the extraction genuinely clean and serviced across the year rather than treating the examination as an annual cliff edge. Systems that are cleaned to a proper schedule, with filters kept clear and fabric kept sound, tend to sail through - because the readings never had a chance to drift in the first place. Keep your reports on file for at least five years, act on the amber points before they turn red, and the test becomes a formality rather than a fright.
Questions
No. A failed or amber result is not a closure notice - it is a graded report telling you which parts of the system have fallen below their design performance. You do need to act on it, and if the failure means contaminants are not being controlled at source you may need interim measures while the fix is arranged. In most kitchens the corrective work is a clean, a fan service and some resealing, followed by a re-test.
Under Regulation 9 of the COSHH Regulations, most LEV systems must have a thorough examination and test at least every fourteen months. Some higher-risk processes need it more often. You should also keep each report for a minimum of five years so you can show inspectors a continuous history of the system being maintained.
That is the most common question we hear, and the answer is usually gradual drift rather than a sudden fault. Grease slowly loads the filters, a fan belt slackens, a flexible duct cracks, and airflow falls a little each month until it drops below the benchmark. Nothing feels different at the pass, but the instruments measure the shortfall precisely - which is exactly what the test is designed to catch.
Phoenix Duct Clean · by the numbers
Phoenix examines and tests local exhaust ventilation to HSG258 and COSHH - measured, reported and certificated, UK-wide.