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LEV testing - the two tests
People sometimes assume an LEV system only gets tested once, or that all LEV tests are the same. In fact there are two distinct checks with different jobs: the commissioning test, done when a system is new, which sets the benchmark of how it should perform; and the thorough examination and test, done regularly through the system's life, which confirms it still performs against that benchmark. Here is how they differ, and why you need both. This is general information.
The short answer
There's a common assumption that an LEV system is tested once and that's that, or that any LEV test is the same as any other. In fact there are two distinct tests, done at different times for different reasons: the commissioning test and the thorough examination and test. Understanding the difference explains why a system needs both. This is general information. The commissioning test: setting the benchmark. The commissioning test is done when an LEV system is new - just installed, before it goes into regular service. It has two jobs. First, it verifies the system works as designed - that it's been installed correctly and achieves the performance it was specified to (it captures and removes the contaminant as intended). Second, and crucially for the long term, it records the benchmark: the performance figures the system achieves when properly set up and working - the airflows, capture velocities, static pressures and other measurements at each hood and point. These commissioning figures become the reference the system is measured against for the rest of its life: they define what 'this system working properly' looks like, in numbers. So the commissioning test establishes both that the system works and how it performs when it does - the standard for everything after. The thorough examination and test: confirming it still performs. The thorough examination and test (often shortened to TExT) is the recurring statutory check required under COSHH - typically at least every fourteen months for most systems (the interval depends on the process). It's the test people usually mean by 'LEV testing'. It has three parts: a thorough examination of the system (its condition, components, signs of wear or damage), a test of its current performance (measuring the airflows, capture velocities and pressures now), and an assessment of whether it's still controlling exposure adequately - which involves comparing the current measurements against the commissioning benchmark. So the thorough examination checks the system as it is now and judges whether it still performs as it should. The key difference: once versus repeatedly, benchmark versus check. So the difference between them is timing and purpose. Commissioning happens once, at the start of the system's life, to establish how the system should perform (and to confirm it does, when new). The thorough examination happens repeatedly, through the system's life (every fourteen months or so), to confirm it still performs as it should (and to catch it if it doesn't). Commissioning sets the standard; the thorough examination checks against it, over and over. They're not alternatives or the same test done twice - they're different tests doing different jobs at different stages. Why you need both. You need both because they depend on each other. Without the commissioning benchmark, a thorough examination has nothing firm to measure current performance against - the tester can measure what the system does now, but 'is that good enough?' is best answered against the figures the system achieved when properly set up and working (the benchmark). Lacking that, the examination has to fall back on design intent or general expectations, which is weaker (this is why a system without commissioning data is harder to examine properly - covered in the why-your-lev-is-benchmarked-against-its-original-design page). And without the recurring thorough examination, the commissioning benchmark just records a system that may since have degraded unnoticed - a benchmark with nothing checking against it. So the two together form the system: commissioning sets the reference, and the recurring thorough examination uses that reference to confirm continued performance. Miss either and the other is weakened. The takeaway. So a commissioning test and a thorough examination and test are two different LEV checks: commissioning is done once when the system is new, to set the benchmark of how it should perform; the thorough examination and test is done repeatedly through the system's life, to confirm it still performs against that benchmark. You need both - the benchmark to measure against, and the recurring test that does the measuring. This is general information - a competent person carries out both. This is general information.
Key points
The commissioning test
The commissioning test is done when an LEV system is new - just installed, before it goes into regular service. It has two jobs. First, it verifies the system works as designed: that it's been installed correctly and achieves the performance it was specified to, capturing and removing the contaminant as intended. So it's the check that the new system is fit for purpose from the start.
Second, and crucial for the long term, it records the benchmark: the performance figures the system achieves when properly set up and working - the airflows, capture velocities, static pressures and other measurements at each hood and point. These commissioning figures become the reference the system is measured against for the rest of its life - they define, in numbers, what 'this system working properly' looks like. So the commissioning test both confirms the new system works and captures how it performs when it does. That recorded benchmark is what every later thorough examination measures against (next). So the commissioning test - setting the benchmark when the system is new - is the start-of-life test: it establishes the standard the system will be held to. Without it, later tests lack a firm reference. So commissioning sets the reference for the system's life. This is general information. This is general information.
The thorough examination and test
The thorough examination and test (often shortened to TExT) is the recurring statutory check required under COSHH - typically at least every fourteen months for most systems (the interval depending on the process). It's the test people usually mean by 'LEV testing'. It has three parts: a thorough examination of the system (its condition, components, and any signs of wear or damage), a test of its current performance (measuring the airflows, capture velocities and pressures now), and an assessment of whether it's still controlling exposure adequately.
That assessment involves comparing the current measurements against the commissioning benchmark - has performance held up, or has it dropped? So the thorough examination checks the system as it is now and judges whether it still performs as it should. Unlike commissioning (done once), the thorough examination is done repeatedly - every fourteen months or so, through the whole life of the system - because a system that was fine at the last check can degrade before the next (a weakening fan, a clogging filter, a developing leak). So it's the ongoing confirmation that the system is still doing its job. So the thorough examination and test - confirming it still performs, again and again - is the recurring test: it repeatedly checks the system's current performance against the benchmark. It relies on the commissioning benchmark to judge against. So the thorough examination is the repeated through-life check. This is general information. This is general information.
The key difference
So the difference between the two tests is timing and purpose. The commissioning test happens once, at the start of the system's life, to establish how the system should perform (and to confirm it does, when new). The thorough examination and test happens repeatedly, through the system's life (every fourteen months or so), to confirm it still performs as it should - and to catch it if it doesn't.
Put simply: commissioning sets the standard; the thorough examination checks against it, over and over. They're not alternatives, and they're not the same test done at different times - they're different tests doing different jobs at different stages of the system's life. The commissioning test is about establishing the reference; the thorough examination is about using that reference to verify continued performance. Confusing them (or assuming one covers the other) leaves a gap: a commissioned but never-re-examined system has a benchmark but no ongoing check; a system examined without a commissioning benchmark has checks but a weak reference. So the key difference - once to set the standard, repeatedly to check it - is the heart of it: two tests, different times, different purposes. Why both are needed follows. So one establishes the standard, the other verifies it repeatedly. This is general information. This is general information.
Why you need both
You need both tests because they depend on each other. Without the commissioning benchmark, a thorough examination has nothing firm to measure current performance against: the tester can measure what the system does now, but the question 'is that good enough?' is best answered against the figures the system achieved when properly set up and working (the benchmark). Lacking that, the examination has to fall back on design intent or general expectations, which is a weaker reference - so a system without commissioning data is harder to examine properly (covered in the why-your-lev-is-benchmarked-against-its-original-design page).
And without the recurring thorough examination, the commissioning benchmark just records a system that may since have degraded unnoticed - a benchmark with nothing checking against it, so no one knows if the system still meets it. So the two together form a complete picture: commissioning sets the reference, and the recurring thorough examination uses that reference to confirm continued performance. Miss either and the other is weakened - a benchmark without checks, or checks without a firm benchmark. This is why a well-managed LEV system has both: a commissioning test when installed (setting the benchmark) and thorough examinations every fourteen months after (checking against it). So why you need both - each depends on the other - is the conclusion: the commissioning benchmark and the recurring thorough examination only work as a pair. So keep both: the benchmark and the repeated check. This is general information. This is general information.
In practice
In practice, this means a new LEV system should be commissioned when installed - not just switched on. The commissioning test confirms it works and, importantly, records the benchmark figures, ideally kept with the system's documentation (alongside the design specification and the LEV logbook). This is the reference that every future thorough examination will use, so it's worth getting done properly at the start (covered in the commissioning-lev-for-a-new-production-line page).
Then, through the system's life, thorough examinations follow at the required interval (typically at least every fourteen months), each measuring against that commissioning benchmark to confirm continued performance. If a system was never commissioned (or the data was lost), that gap should be addressed - a competent tester can sometimes establish a benchmark from the design and testing, but it's not as firm as proper commissioning data. The thorough examination and test is also distinct from routine servicing and maintenance (keeping the system running well between tests), which is covered in the the-difference-between-lev-servicing-and-lev-testing page. So in practice - a new system needs commissioning first - is the action: commission a new system to set its benchmark, then thoroughly examine it regularly against that benchmark. Both, in order. So commission first, then examine regularly. This is general information. This is general information.
Questions
Commissioning is a one-off test when the LEV is new, setting the benchmark of how it should perform; a thorough examination and test is the recurring statutory check (typically at least every 14 months) confirming it still performs against that benchmark - so one sets the standard, the other repeatedly checks it. A commissioning test and a thorough examination and test are two different LEV checks. The commissioning test is done once, when the system is new (just installed): it verifies the system works as designed and records the benchmark - the performance figures (airflows, capture velocities, pressures) the system achieves when properly set up and working, which become the reference for the rest of its life. The thorough examination and test (often shortened to TExT) is the recurring statutory check required under COSHH - typically at least every fourteen months - which thoroughly examines the system, tests its current performance, and compares that against the commissioning benchmark to confirm it still performs as it should. So the difference is timing and purpose: commissioning happens once, to set how the system should perform; the thorough examination happens repeatedly, to confirm it still does. Commissioning sets the standard; the thorough examination checks against it, over and over. So one is the start-of-life benchmark, the other the through-life check. So commissioning sets the standard; the exam repeatedly checks it. This is general information. This is general information.
It's done when an LEV system is new, to verify it works as designed and to record the benchmark - the performance figures it achieves when properly set up - which become the reference every later thorough examination measures against; so it both proves the new system works and sets the standard for its life. A commissioning test is done when an LEV system is new - just installed, before regular service - and it has two purposes. First, it verifies the system works as designed: that it's been installed correctly and achieves the performance it was specified to, capturing and removing the contaminant as intended. So it confirms the new system is fit for purpose from the start. Second, and crucial for the long term, it records the benchmark: the performance figures the system achieves when properly set up and working - the airflows, capture velocities, static pressures and other measurements at each hood. These commissioning figures become the reference the system is measured against for the rest of its life, defining in numbers what 'this system working properly' looks like. So the commissioning test both proves the new system works and captures how it performs when it does - and that recorded benchmark is what every later thorough examination measures against. Without it, later tests lack a firm reference. So it's for confirming the new system and setting its lifelong benchmark. So it verifies the new system and records its benchmark. This is general information. This is general information.
Typically at least every 14 months for most LEV systems - the standard interval under COSHH (some higher-risk processes need it more often) - because a system that was fine at the last check can degrade before the next, so it's repeated through the system's life to confirm continued performance. A thorough examination and test is needed regularly - typically at least every fourteen months for most LEV systems. That's the standard maximum interval under COSHH (some higher-risk processes, and certain substances, require it more frequently - the assessment sets the interval). Unlike the commissioning test (done once), the thorough examination is repeated through the whole life of the system, because a system that was performing fine at the last check can degrade before the next: a weakening fan, a clogging filter, a developing leak or blockage can all reduce performance over months. So the recurring examination catches degradation that would otherwise go unnoticed. Each examination thoroughly examines the system's condition, tests its current performance, and compares that against the commissioning benchmark to confirm it still controls exposure. So the fourteen-month cycle is about ongoing assurance - repeatedly confirming the system still performs, rather than assuming it does. So it's needed at least every fourteen months, repeatedly. So typically at least every 14 months, through the system's life. This is general information. This is general information.
Because they depend on each other - without the commissioning benchmark, a thorough examination has no firm reference to judge current performance against; without the recurring thorough examination, the benchmark just records a system that may have degraded unnoticed; together, one sets the reference and the other checks against it. You need both tests because they depend on each other. Without the commissioning benchmark, a thorough examination has nothing firm to measure current performance against: the tester can measure what the system does now, but the question 'is that good enough?' is best answered against the figures the system achieved when properly set up and working. Lacking that benchmark, the examination falls back on design intent or general expectations - a weaker reference, making the system harder to examine properly. And without the recurring thorough examination, the commissioning benchmark just records a system that may since have degraded unnoticed - a benchmark with nothing checking against it, so no one knows if the system still meets it. So the two together form a complete picture: commissioning sets the reference, and the recurring thorough examination uses that reference to confirm continued performance. Miss either and the other is weakened - a benchmark without checks, or checks without a firm benchmark. So a well-managed system has both: commissioning when installed, thorough examinations every fourteen months after. So because the benchmark and the recurring check only work as a pair. So because each is weaker without the other. This is general information. This is general information.
No - a thorough examination and test is the statutory check of whether the system still performs (measuring against the benchmark), while servicing and maintenance keep the system running well between tests; they're different activities, both needed, and the examination isn't a substitute for maintenance or vice versa. No - a thorough examination and test is not the same as servicing the LEV. The thorough examination and test is the statutory check, required under COSHH (typically at least every fourteen months), of whether the system still performs and controls exposure - it examines the system's condition, tests its current performance, and compares that against the commissioning benchmark. It's an assessment: does the system still do its job? Servicing and maintenance, by contrast, is the routine work of keeping the system running well between tests - cleaning or changing filters, fixing worn parts, keeping the fan and ducts in good order. It's upkeep, not assessment. They're different activities, and both are needed: maintenance keeps the system performing, and the thorough examination confirms it still does. One isn't a substitute for the other - a system can pass an examination and still need routine maintenance, and good maintenance doesn't remove the legal need for the examination. This is covered further in the the-difference-between-lev-servicing-and-lev-testing page. So no - the examination assesses, servicing maintains; both are needed. So no; testing checks it, servicing maintains it. This is general information. This is general information.
It's a gap worth addressing - without commissioning data, thorough examinations lack a firm benchmark to judge performance against, so they fall back on design intent; a competent tester can sometimes establish a benchmark from the design and testing, but proper commissioning data is firmer, so commission new systems properly. If your LEV was never commissioned (or the commissioning data was lost), it's a gap worth addressing, because it weakens the thorough examinations that follow. Without commissioning data, a thorough examination has no firm benchmark of how the system should perform to judge current performance against - so it falls back on the design intent or general expectations, which is a weaker reference. This makes it harder to say confidently whether the system is still performing adequately or has degraded. What can be done: a competent tester can sometimes establish a benchmark from the system's design specification and testing (working out what it should achieve and measuring what it does), which gives the examinations something to work with - though it's not as firm as proper commissioning data recorded when the system was new and known to be working. So the lesson for new systems is to commission them properly at installation (setting the benchmark from the start), and for existing systems without commissioning data, to have a competent tester establish the best benchmark they can. This connects to the why-your-lev-is-benchmarked-against-its-original-design page. So address the gap - establish a benchmark - and commission future systems properly. So it's a gap; get a benchmark established and commission new systems. This is general information. This is general information.
A commissioning test sets your LEV system's benchmark when new, and a thorough examination and test confirms it still performs against that benchmark every fourteen months or so; we carry out the thorough examination and test your system needs, measuring against its benchmark to prove it still controls exposure. Ask us to test your LEV. This is general information.
