What's measured
When an examiner tests your extraction, they are not asking whether it moves air in some general sense. They are asking whether it still performs the way it did when it was commissioned - against the numbers recorded when the system was proven to work. That original design benchmark is the whole point of the test.
The short answer
When an examiner tests your extraction, they are not asking whether it moves air in some general sense. They are asking whether it still performs the way it did when it was commissioned - against the numbers recorded when the system was proven to work. That original design benchmark is the whole point of the test.
The detail
Every properly installed LEV system should be commissioned: run up, measured, and recorded against its design intent, with the results written into a commissioning report and a logbook or user manual kept with the system. Those documents capture the airflow, capture velocity and static pressures the system delivered when it was new and known to be controlling exposure. They are the datum - the reference the system will be judged against for the rest of its life.
A thorough examination and test then measures the same points and compares them to that datum. A hood pulling less than its commissioned figure, a static pressure that has shifted, a duct velocity that has dropped - each is only meaningful because there is a known-good value to compare against. Working answers nothing on its own; working compared to what it was designed to do is the question that matters. In practice those records set out the airflow or velocity at each hood, the static pressures around the system and the fan's duty, giving the examiner a specific figure to test every point against rather than a general impression of the system.
What it means for you
This is why the commissioning data and logbook are not paperwork to be lost in a drawer. Without them, an examiner arriving for a fourteen-month test has no baseline and must reconstruct or estimate what good should look like - a weaker, slower and less certain judgement than comparing against a figure the system actually achieved. Keeping the records with the system is a small discipline that makes every future test sharper, and the reports themselves should be kept for at least five years.
Benchmarking against the original design is also what catches slow decline. Filters load, ducts leak, fans wear and hoods get knocked out of position gradually, so a system rarely fails all at once. Held against its commissioning figures, a gentle downward drift shows up as a number, long before a worker notices anything wrong. Spotting that drift at a fourteen-month examination, rather than after a health scare, is the whole difference the benchmark makes.
The service behind the guide
We test your system against its commissioning benchmark, or help establish one where the records are missing, with a clear report and remedial actions.
Questions
Against its original commissioning data - the airflow, capture velocity and static pressures the system recorded when it was installed and proven to control exposure. The test compares today's readings to that baseline.
In the commissioning report and the system's logbook or user manual, which should be kept with the LEV. These document the as-designed performance.
The examiner has no baseline to compare against and must reconstruct or estimate what good performance should be. That is a weaker judgement, so it is worth establishing and recording a benchmark.
Because working has no meaning without a reference. A hood can still pull air and still be well below the airflow it needs. Comparing against the design figure is what reveals the shortfall.
Systems decline slowly as filters load and fans wear. Measured against commissioning figures, a small downward drift appears as a falling number long before anyone notices contaminant escaping.
Phoenix Duct Clean · by the numbers
We test your system against its commissioning benchmark - or help establish one where the records are missing - with a clear report and remedial actions.