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LEV testing - spray booths
A spray booth sits in an interesting place. It is an extraction system whose ducts collect overspray and need cleaning - and it is also, in effect, LEV controlling the paint mist and solvent vapour the spraying releases. So a spray booth needs both its ductwork kept clean and its extraction performance tested, and understanding where those two overlap and where they differ is worth getting straight.
The short answer
A spray booth is both a duct system that collects overspray and, effectively, LEV controlling the paint mist and solvent vapour that spraying releases. So it has two related but distinct needs. First, its ductwork and filters need cleaning, because overspray builds up in them - a fouling and often a fire-risk issue. Second, its extraction performance needs testing, because as LEV controlling a health hazard it has to actually capture the mist and vapour effectively. The two overlap - both concern the same system, and a fouled system both needs cleaning and performs worse - but they are different questions: one is about cleanliness, the other about whether the extraction genuinely controls exposure.
A spray booth is two things at once
A spray booth is worth thinking about carefully because it plays two roles at once. On one hand it is an extraction system with ductwork - it draws air through the booth to carry away overspray, and that overspray collects in the filters and ducts, which therefore need cleaning like any extraction system that accumulates deposits. On the other hand it is, in effect, local exhaust ventilation: spraying releases paint mist and solvent vapour, both hazardous to health, and the booth's extraction is what controls the operator's exposure to them by drawing the contaminated air away. So the same equipment is both a duct system to keep clean and a health control to keep effective.
This dual nature is why a spray booth has two related maintenance needs that are easy to conflate but genuinely distinct. Keeping the ductwork clean addresses the accumulation of overspray - a fouling and fire-safety matter. Testing the extraction performance addresses whether the booth is actually controlling the operator's exposure to the mist and vapour - a health-control matter. Both are about the same system, and they interact, but they answer different questions. Getting the two straight - what each is for, where they overlap, where they differ - is how a spray booth gets looked after properly on both fronts.
The cleaning need
The first need is cleaning, driven by overspray. Not all the paint sprayed lands on the workpiece; a good deal becomes airborne mist that the booth's extraction draws away, and that overspray deposits in the booth's filters and ductwork as it passes through. Over time it builds up - filters clog, ducts accumulate layers of dried paint and solvent residue. This has to be cleaned out, for two reasons. It fouls the system, and a fouled system with clogged filters and coated ducts extracts less effectively. And, importantly, paint overspray deposits can be a fire hazard, especially with solvent-based products, so their accumulation is a safety matter as much as a performance one.
So spray booth duct and filter cleaning is a real and necessary maintenance task in its own right - keeping the overspray from building up to the point where it fouls the extraction or becomes a fire risk. This is the aspect that most obviously resembles the duct-cleaning need of any extraction system that collects deposits: the system gets dirty with use and has to be cleaned to stay safe and functional. The frequency depends on how much the booth is used and what is sprayed, but the principle is constant - overspray accumulates, and it has to be removed. This is the cleaning side of looking after a spray booth.
The testing need
The second need is testing the extraction performance, driven by the booth's role as a health control. Spraying exposes the operator to paint mist and solvent vapour, both hazardous, and the booth's extraction is what controls that exposure - which makes it subject to the same logic as any LEV controlling a health hazard. It is not enough for the booth to be running and drawing air; it has to be drawing enough air, in the right pattern, to actually control the operator's exposure to the mist and vapour. Confirming that requires measuring the extraction performance, the way any LEV is tested - not just observing that the system is on.
This is a different question from cleanliness. A booth can be clean and still not extract adequately if, say, the fan is underperforming or the airflow pattern is wrong; and testing the extraction performance answers whether the operator is actually being protected, which cleaning alone does not. Because the booth controls exposure to substances hazardous to health, this performance testing is the health-and-safety heart of looking after it - the confirmation that the control is genuinely working. So alongside keeping the ducts clean, a spray booth needs its extraction performance tested to confirm it is doing its job as a health control, exactly as other LEV does.
Where they overlap and differ
The overlap between the two is real and worth understanding. Both concern the same system, and they interact: a fouled, uncleaned booth both needs cleaning and performs worse as a control, because the overspray clogging its filters and ducts reduces the airflow that does the extraction. So cleaning the system supports its performance, and a system kept clean is more likely to test well. In that sense the cleaning and the testing pull in the same direction, and neglecting the cleaning undermines the extraction. They are two aspects of caring for one system, and they reinforce each other.
But they are not the same thing, and one does not substitute for the other. Cleaning removes the overspray and addresses the fouling and fire risk, but it does not by itself confirm the extraction controls exposure - a clean booth can still under-perform. Testing measures whether the control works, but it is not a substitute for the cleaning that keeps the system safe from fire and functioning. So a spray booth needs both: the cleaning to keep the overspray under control, and the performance testing to confirm it is protecting the operator. Understanding that they overlap - same system, mutually supporting - but differ - cleanliness versus capture - is what ensures a booth gets looked after on both fronts rather than one being mistaken for the other.
The takeaway
A spray booth is both a duct system that collects overspray and, in effect, LEV controlling the paint mist and solvent vapour the operator is exposed to - so it has two related but distinct needs. Its ductwork and filters need cleaning, because overspray builds up and fouls the system and can become a fire risk. And its extraction performance needs testing, because as a health control it has to actually capture the mist and vapour effectively, which only measurement confirms.
The two overlap - they concern the same system and support each other, since a fouled booth both needs cleaning and extracts worse - but they answer different questions: one is about cleanliness and fire safety, the other about whether the extraction genuinely controls exposure. Neither substitutes for the other. A well-looked-after spray booth gets both: the ducts kept clean of overspray, and the extraction tested to confirm it is protecting the operator. Getting the overlap and the difference straight is how a booth is properly maintained on both fronts.
Questions
Because it is two things at once: an extraction system whose ducts collect overspray and need cleaning, and effectively LEV controlling the paint mist and solvent vapour the operator is exposed to. So it needs both its ductwork kept clean and its extraction performance tested as a health control.
Because overspray - the paint mist that does not land on the workpiece - deposits in the filters and ductwork and builds up over time. It fouls the system and reduces extraction, and paint deposits, especially solvent-based, can be a fire hazard, so their accumulation is a safety matter as well as a performance one.
Because spraying exposes the operator to paint mist and solvent vapour, both hazardous, and the booth's extraction controls that exposure - making it LEV controlling a health hazard. It has to draw enough air, in the right pattern, to actually control exposure, which only measuring the performance confirms.
They concern the same system and support each other: a fouled, uncleaned booth both needs cleaning and extracts worse, because the overspray clogging its filters and ducts reduces the airflow. So cleaning supports performance, and a clean booth is more likely to test well. They reinforce each other.
They answer different questions. Cleaning removes overspray and addresses fouling and fire risk but does not confirm the extraction controls exposure - a clean booth can still under-perform. Testing measures whether the control works but is not a substitute for the cleaning that keeps the system safe from fire.
Yes. Neither substitutes for the other: the cleaning keeps the overspray under control for safety and function, and the performance testing confirms the extraction is protecting the operator. A well-maintained booth gets both, because it is both a duct system to keep clean and a health control to keep effective.
A spray booth is a health control as well as a duct system - our thorough examination tests whether its extraction genuinely controls the operator's exposure to paint mist and solvent vapour, alongside keeping its ducts clean.
