Maintenance & systems
The best time to get LEV right is before you buy it. A clear specification - what substance it must control, from which process, to what performance, with commissioning required - turns a purchase from a hopeful guess into a system designed for your actual hazard, and gives you something concrete to hold the supplier to.
The short answer
The best time to get LEV right is before you buy it. A clear specification - what substance it must control, from which process, to what performance, with commissioning required - turns a purchase from a hopeful guess into a system designed for your actual hazard, and gives you something concrete to hold the supplier to.
The detail
A great deal of LEV disappointment traces back to buying before specifying. A system chosen from a catalogue or a rough brief may look right and still control the wrong thing, or control the right thing badly, because it was never told precisely what job it had to do. Writing a specification first forces the questions that determine whether the extraction will actually work, and turns the purchase into a defined engineering requirement rather than a hopeful order.
It starts with the hazard. The specification should identify the substance the LEV must control, and how the process generates it - as fine dust, welding fume, mist or vapour, thrown off fast or drifting slowly, from a fixed point or a moving one. This is what determines the hood type, the capture velocity needed and the whole design, because a system that suits a slow vapour will not hold a fast-moving dust cloud, and only the process detail reveals which you have.
From there it sets performance. A good specification states the capture the system must achieve at each source and the flow and pressure targets that go with it, rather than leaving 'adequate' to interpretation. It should also address the practicalities that make or break real installations - make-up air provision, filtration suited to the contaminant, discharge arrangements and access for future maintenance and testing.
Crucially, it should require commissioning as part of the deal. Specifying that the supplier must commission the finished system, demonstrate it meets the stated performance at every hood, and hand over a full commissioning report means you buy a proven system with its baseline documented - not just an installation you then have to test to find out whether it works. Building that in from the start is far easier than extracting it afterwards.
What it means for you
A well-specified system arrives fit for its actual purpose, with its performance demonstrated and its baseline recorded, ready to join the examination and maintenance cycle from day one. The specification also gives you leverage: a concrete standard to hold the supplier to, so 'it does not seem to capture much' becomes 'it does not meet the capture we specified', which is a very different conversation.
It heads off the expensive failures too. Systems bought without a specification are the ones that turn out undersized, starved of make-up air, aimed at the wrong emission or impossible to maintain - faults that are cheap to prevent on paper and costly to fix in steel once installed. The specification is where those mistakes are caught, before any money is committed.
Writing an LEV specification before buying is, in the end, how you make sure the system you pay for is the system you need. It aligns the supplier, the design and the eventual commissioning around your real hazard, and it gives you a proven, documented, maintainable system rather than an expensive guess bolted to the workshop wall.
The service behind the guide
Sibling guides
Why LEV alone is not enough · Retrofitting LEV in an older workshop · Why LEV quotes differ site to site
Questions
Because a system bought without one may control the wrong thing, or control it badly. Specifying first turns the purchase into a defined engineering requirement designed for your actual hazard.
The substance to be controlled and how the process emits it, the capture performance and flow and pressure targets, make-up air and filtration, discharge, maintenance access, and a commissioning requirement.
Because how a contaminant is generated - fast dust or slow vapour, fixed or moving source - determines the hood type and capture velocity. Only the process detail reveals what design the system actually needs.
Yes. Requiring the supplier to commission the system, prove it meets the stated performance and hand over a commissioning report means you buy a proven system with a documented baseline.
Leverage. A concrete performance standard lets you hold the supplier to what was agreed, so a shortfall becomes a failure to meet the specification rather than a matter of opinion.
Phoenix Duct Clean · by the numbers
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