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LEV testing - layout and extraction
Extraction doesn't work in isolation - how well it captures depends a lot on the workshop around it. Where machines sit relative to their hoods, how long and convoluted the duct runs are, and where draughts and cross-flows come from all shape whether the extraction actually captures the contaminant. Here is how workshop layout affects extraction performance, and why changing the layout can break a system that worked. This is general information.
The short answer
It's natural to think of extraction as a self-contained system - buy it, install it, it works. But how well extraction captures the contaminant depends heavily on the workshop around it. The physical layout - where machines sit, how the ducts run, where the draughts are - shapes the capture, the airflow and the air movement that the system relies on. Understanding this explains both why a well-laid-out workshop extracts well and why changing a layout can quietly break a system. Here's how workshop layout affects extraction performance. This is general information. Machine-hood position: the biggest factor. The single biggest way layout affects extraction is the position of each machine relative to its hood. Capture falls off very quickly with distance from a hood, so the contaminant only gets captured if it's generated close to, and in the right relationship to, the hood. If a machine sits too far from its hood, or the work happens on the wrong side of it, the contaminant escapes into the workshop rather than being drawn in. So the layout - specifically where each machine is placed relative to its capture point - directly determines whether the extraction captures the dust or fume. This is why a machine moved even a modest distance from where its hood was set up can stop being properly captured (covered in the hood-and-capture-point-design page). Duct runs: length and routing cost airflow. The layout also shapes the ductwork, and the duct runs affect the airflow. A sprawling or awkward layout forces long, convoluted duct routing (bends, long runs, detours around obstacles), and every bit of extra length and every bend adds resistance that costs airflow - so the extraction is weaker at the hoods. And in long or low-velocity runs (which awkward routing tends to create), dust can settle and gradually block the ducts, further reducing performance. So a layout that forces bad ductwork weakens the extraction, whereas a compact layout allowing short, direct runs supports it. Draughts and cross-flows: disrupting capture. Air movement across the workshop - draughts and cross-flows - can disrupt capture at the hood. A hood captures by drawing air (and the contaminant) inward, but that capturing airflow is relatively gentle and can be overpowered by a stronger air movement across it. So a draught from an open door, a cross-flow from a fan or ventilation, or air movement from people and machines passing can blow the contaminant past the hood before it's captured. This means the same hood captures worse in a draughty spot than in still air - so where a machine and hood sit in relation to doors, windows and other air movement (a layout matter) affects the capture. General crowding and access. More broadly, the general crowding and arrangement of the workshop affects extraction. A cramped or cluttered layout can block airflow (obstructions disrupting the air movement around hoods), obstruct the hoods (clutter or equipment stopping a hood being positioned or working well), and make the extraction hard to reach for maintenance and testing (so it's less likely to be kept working). So a well-organised layout supports the extraction; a crowded, cluttered one hampers it. Why layout changes can break extraction. The key practical consequence of all this is that changing the layout can break extraction that was working. Because the extraction's performance depends on these layout-related relationships - the machine-hood distance, the duct routing, the draughts - changing the layout changes those relationships, and can undermine the capture. Moving a machine can put it out of its hood's effective capture zone. Adding equipment can obstruct a hood or airflow. Changing where a door or ventilation is can introduce a draught that disrupts capture. Rearranging the space can change the whole air-movement pattern. So a system that was capturing well in one layout isn't automatically fine in another - a layout change can quietly stop it working, without any change to the extraction equipment itself (covered in the how-modifying-your-workshop-layout-breaks-your-lev page). What to do about it. So after any significant layout change - moving a machine, adding equipment, changing doors or ventilation, rearranging the workshop - the extraction should be checked, and re-tested, to confirm it still captures the contaminant. You can't assume a system proven in the old layout still works in the new one. Better still, layout and extraction should be considered together: when planning a change, think about its effect on the extraction (will the machine still be in its hood's capture zone, will a new draught disrupt a hood), so the change doesn't break the control. And extraction designed into a workshop from the start (with the layout in mind) performs better than extraction bolted onto whatever layout emerges (covered in the how-to-design-dust-extraction-into-a-workshop page). The takeaway. So workshop layout affects extraction performance in several ways: the position of each machine relative to its hood (the biggest factor), the length and routing of the duct runs, the draughts and cross-flows that can disrupt capture, and the general crowding and access. Because the extraction depends on these layout relationships, changing the layout can break a working system - so any layout change should prompt a check and re-test of the extraction, and layout and extraction are best planned together. This is general information. This is general information.
Key points
Machine-hood position
The single biggest way layout affects extraction is the position of each machine relative to its hood. Capture falls off very quickly with distance from a hood, so the contaminant only gets captured if it's generated close to, and in the right relationship to, the hood. If a machine sits too far from its hood, or the work happens on the wrong side of it, the contaminant escapes into the workshop rather than being drawn in.
So the layout - specifically where each machine is placed relative to its capture point - directly determines whether the extraction captures the dust or fume. This is why a machine moved even a modest distance from where its hood was set up can stop being properly captured: the small effective capture zone means position is critical (covered in the hood-and-capture-point-design-why-it-makes-or-breaks-extraction page). This makes the machine-hood relationship the most important layout factor for extraction - get it right and capture happens, get it wrong (too far, wrong side) and it doesn't, however good the rest of the system. So machine-hood position - the biggest factor in capture - is where layout matters most: the contaminant must be generated within the hood's capture zone. The ductwork and air-movement factors follow. So a machine must sit within its hood's capture zone. This is general information. This is general information.
Duct runs
The layout also shapes the ductwork, and the duct runs affect the airflow. A sprawling or awkward layout forces long, convoluted duct routing - bends, long runs, detours around obstacles - and every bit of extra length and every bend adds resistance that costs airflow. So the more tortuous the ductwork (a consequence of the layout), the weaker the extraction is at the hoods, because the fan's effort is spent overcoming the duct resistance rather than pulling air at the capture points.
And in long or low-velocity runs (which awkward routing tends to create), dust can settle and gradually block the ducts, further reducing performance over time. So a layout that forces bad ductwork weakens the extraction twice over - immediately through added resistance, and progressively through settling and blockage. By contrast, a compact, sensible layout that allows short, direct duct runs supports strong extraction. This is one reason extraction designed into a workshop (with the layout planned for good ductwork) outperforms extraction bolted onto whatever layout emerges. So duct runs - length and routing cost airflow - is the second layout factor: the layout shapes the ductwork, which shapes the airflow. Air movement across the workshop is next. So sprawling layouts force airflow-sapping ductwork. This is general information. This is general information.
Draughts and cross-flows
Air movement across the workshop - draughts and cross-flows - can disrupt capture at the hood. A hood captures by drawing air (and the contaminant in it) inward, but that capturing airflow is relatively gentle, and it can be overpowered by a stronger air movement across it. So a draught from an open door, a cross-flow from a fan or a ventilation supply, or air movement from people and machines passing can blow the contaminant past the hood before it's captured.
This means the same hood captures worse in a draughty spot than in still air - the draught competing with, and defeating, the hood's gentle capturing flow. So where a machine and its hood sit in relation to doors, windows, ventilation and other sources of air movement (all layout matters) affects how well the extraction captures. A hood placed right by a frequently-opened door, or in the path of a ventilation cross-flow, is fighting the air movement; the same hood in a still corner captures better. This is a subtle but real layout effect, easy to overlook because the extraction equipment is identical - only its position in the workshop's air-movement pattern differs. So draughts and cross-flows - air movement that disrupts capture - is the third layout factor: the workshop's air movement can defeat a hood's capture. General crowding is next. So draughts can blow the contaminant past the hood. This is general information. This is general information.
Crowding and access
More broadly, the general crowding and arrangement of the workshop affects the extraction. A cramped or cluttered layout can block airflow - obstructions disrupting the air movement around hoods, or getting in the way of the capture. It can obstruct the hoods themselves - clutter, stored materials or other equipment stopping a hood being positioned well or working freely. And it can make the extraction hard to reach for maintenance and testing - so the system is less likely to be kept working and verified.
So a well-organised, uncluttered layout supports the extraction (clear airflow, unobstructed hoods, accessible system), while a crowded, cluttered one hampers it in several ways at once. This general effect compounds the specific ones (machine-hood position, ductwork, draughts): a cramped workshop tends to have machines squeezed away from ideal hood positions, awkward ductwork, and obstructed airflow, all together. And the access problem matters beyond capture - a system that's hard to reach is hard to maintain and test, so it's more likely to degrade unnoticed. So crowding and access - a cramped layout hampers extraction - is the fourth layout factor: general arrangement affects capture, airflow and maintainability. Why layout changes break extraction, and what to do, is next. So a cluttered workshop works against its extraction. This is general information. This is general information.
Why changes break it, and what to do
The key practical consequence of all this is that changing the layout can break extraction that was working. Because the extraction's performance depends on these layout relationships - the machine-hood distance, the duct routing, the draughts - changing the layout changes those relationships and can undermine the capture. Moving a machine can put it out of its hood's effective capture zone. Adding equipment can obstruct a hood or airflow. Changing where a door or ventilation is can introduce a disruptive draught. Rearranging the space can change the whole air-movement pattern. So a system capturing well in one layout isn't automatically fine in another - a layout change can quietly stop it working, with no change to the equipment itself (covered in the how-modifying-your-workshop-layout-breaks-your-lev page).
So after any significant layout change - moving a machine, adding equipment, changing doors or ventilation, rearranging the workshop - the extraction should be checked, and re-tested, to confirm it still captures the contaminant. You can't assume a system proven in the old layout still works in the new one. Better still, plan layout and extraction together: when planning a change, consider its effect on the extraction (will the machine stay in its hood's zone, will a new draught disrupt a hood), so the change doesn't break the control. And extraction designed into a workshop from the start, with the layout in mind, performs better than extraction bolted onto whatever layout emerges (covered in the how-to-design-dust-extraction-into-a-workshop page). So why changes break it, and what to do - re-check the extraction after any layout change - is the practical upshot: layout changes can break extraction, so check and re-test after them, and plan the two together. So treat a layout change as a reason to re-check the extraction. This is general information. This is general information.
Questions
Through the position of each machine relative to its hood (capture falls off fast with distance), the length and routing of the duct runs (which cost airflow), the draughts and cross-flows that can disrupt capture, and the general crowding and access - so the workshop around the extraction shapes how well it captures. Workshop layout affects extraction performance in several ways, because extraction depends on the physical arrangement around it. The biggest factor is the position of each machine relative to its hood: capture falls off fast with distance, so a machine too far from its hood, or with the work on the wrong side, isn't captured (the contaminant escapes). The duct runs matter too: a sprawling layout forces long, convoluted ductwork that adds resistance and costs airflow, and low-velocity awkward runs let dust settle and block them. Draughts and cross-flows affect capture: air movement across the workshop (from doors, ventilation, passing traffic) can overpower a hood's gentle capturing flow and blow the contaminant past it, so a hood captures worse in a draughty spot. And general crowding and access matter: a cramped, cluttered layout blocks airflow, obstructs hoods, and makes the system hard to maintain and test. So the layout - machine-hood positions, ductwork, draughts, crowding - shapes how well the extraction captures, not just the equipment. This is also why changing the layout can break a working system. So layout shapes capture through position, ducts, draughts and crowding. So through machine-hood position, ducts, draughts and crowding. This is general information. This is general information.
Yes - because capture falls off fast with distance, moving a machine even a modest amount from where its hood was set up can put it outside the hood's effective capture zone, so the contaminant escapes rather than being captured; so a machine move can quietly break the extraction and should prompt a re-check. Yes - moving a machine can stop its extraction working. This is because capture at a hood falls off very quickly with distance: the effective capture zone is small, so the contaminant only gets drawn in if it's generated close to, and in the right relationship to, the hood. When you move a machine, you change its position relative to its hood - and even a modest move can put the machine (or the point where the dust or fume is generated) outside the hood's effective capture zone. When that happens, the contaminant escapes into the workshop rather than being captured, so the extraction is no longer protecting the operator, even though the equipment is unchanged and still running. This is a common and easily-missed way extraction gets quietly broken: a machine is moved for space or workflow reasons, and no one realises the extraction has stopped capturing because nothing about the extraction itself changed. So a machine move is a real risk to the extraction, and should prompt a check (and re-test) to confirm the machine is still within its hood's capture zone. It's one reason layout changes and extraction have to be considered together. So yes - moving a machine can put it out of its hood's capture zone. So yes; even a small move can stop capture. This is general information. This is general information.
Because a hood captures with a relatively gentle inward airflow, which a stronger air movement across it (a draught from a door, a cross-flow from ventilation or passing traffic) can overpower, blowing the contaminant past the hood before it's captured - so the same hood captures worse in a draughty spot than in still air. Draughts affect extraction because they can overpower a hood's capturing airflow. A hood captures the contaminant by drawing air (and the contaminant in it) inward towards the hood - but that capturing airflow is relatively gentle, especially a little distance from the hood. A stronger air movement across the hood can overpower that gentle inward flow: a draught from an open door, a cross-flow from a fan or a ventilation supply, or air movement from people and machines passing can blow the contaminant past the hood before it's drawn in and captured. So the same hood captures worse in a draughty spot than in still air - the draught competes with, and can defeat, the hood's capture. This means where a machine and its hood sit relative to doors, windows, ventilation and other air-movement sources (a layout matter) affects how well the extraction works: a hood by a frequently-opened door or in a ventilation cross-flow is fighting the air movement, while the same hood in a still corner captures better. It's a subtle effect because the equipment is identical - only its position in the workshop's air-movement pattern differs. So draughts matter, and a hood's position relative to them is a real layout consideration. So because a draught can overpower the hood's gentle capturing flow. So because they blow the contaminant past the hood. This is general information. This is general information.
Because the extraction's performance depends on layout relationships - machine-hood distance, duct routing, draughts - and changing the layout changes them: moving a machine can put it out of its hood's zone, added equipment can obstruct a hood, a new door or ventilation can introduce a draught; so a system fine in one layout may not be in another. Changing a workshop layout can break the extraction because the extraction's performance depends on layout-related relationships, and changing the layout changes those relationships. The extraction relies on: each machine being within its hood's capture zone (a distance/position relationship); reasonable duct routing (a layout-driven factor); and hoods not being disrupted by draughts (a position-relative-to-air-movement factor). A layout change can undermine any of these. Moving a machine can put it out of its hood's effective capture zone, so it's no longer captured. Adding equipment can obstruct a hood or block the airflow around it. Changing where a door or ventilation is can introduce a draught that blows the contaminant past a hood. Rearranging the space can alter the whole air-movement pattern the hoods work in. So a system that was capturing well in the old layout isn't automatically fine in the new one - the change can quietly stop it working, with no change to the extraction equipment itself (so it's easy to miss). This is why any significant layout change should prompt a check and re-test of the extraction, to confirm it still captures. So because layout changes alter the relationships the extraction depends on. So because it changes the positions and airflows the capture relies on. This is general information. This is general information.
Yes - a layout change (moving a machine, adding equipment, changing doors or ventilation) can break extraction that was working, without any change to the equipment, so you can't assume it still captures; check and re-test after any significant change to confirm it still protects people, and ideally plan layout and extraction together. Yes - you should re-check and re-test the extraction after any significant layout change. A layout change - moving a machine, adding equipment, changing where doors or ventilation are, rearranging the workshop - can break extraction that was working, by changing the relationships the extraction depends on (the machine-hood distance, the duct routing, the draughts). Crucially, this can happen with no change to the extraction equipment itself, so the system still looks and sounds like it's working while actually no longer capturing properly - which is exactly why it's easy to miss and important to check. So you can't assume a system proven in the old layout still works in the new one; you have to verify it. After a significant layout change, have the extraction checked and re-tested (a thorough examination and test against its benchmark) to confirm it still captures the contaminant in the new arrangement. Better still, plan layout and extraction together: when planning a change, consider its effect on the extraction (will the machine stay in its hood's zone, will a new draught disrupt a hood), so the change doesn't break the control in the first place. So yes - treat any layout change as a reason to re-check and re-test the extraction. So yes; verify the extraction still captures after any change. This is general information. This is general information.
Yes - extraction designed into a workshop with the layout planned (machines near their hoods, short direct duct runs, hoods away from draughts, an uncluttered arrangement) performs better than extraction bolted onto whatever layout emerges; planning the two together avoids the layout working against the extraction. Yes - designing extraction with the layout in mind helps a great deal. Because layout so strongly affects extraction performance (machine-hood position, duct routing, draughts, crowding), designing the two together produces a system that works well, while bolting extraction onto whatever layout has emerged tends to fight the layout. Extraction designed into a workshop with the layout planned can: place machines close to their hoods (within the capture zone); allow short, direct duct runs (good airflow, less settling); position hoods away from draughts and cross-flows (better capture); and keep an uncluttered arrangement (clear airflow, accessible system). So the layout supports the extraction rather than working against it. By contrast, extraction bolted onto an existing or ad-hoc layout often ends up with machines awkwardly placed relative to hoods, convoluted ductwork, hoods in draughts, and crowding - all the layout factors working against capture. This is why extraction is best designed into a workshop from the start, with the layout considered (covered in the how-to-design-dust-extraction-into-a-workshop page), and why layout changes should be planned with the extraction in mind. So planning layout and extraction together gives far better performance than treating them separately. So yes - planning them together makes the extraction work much better. So yes; designing the two together avoids the layout fighting the extraction. This is general information. This is general information.
A workshop's layout shapes how well its extraction captures - and a layout change can quietly break a working system; we thoroughly examine and test LEV, confirming it still captures the contaminant in the workshop as it actually is - so after any move or change, you know the extraction still protects people. Ask us to test your LEV. This is general information.
