Dust on a shop floor kills desktop computers two ways: conductive grit bridges boards, and a fuzz blanket suffocates heatsinks. Two builds stop it, and the heat decides which one you order. Seal a fanless computer in a gasketed stainless enclosure and no dust-bearing air ever enters; the walls then have to shed every watt, which caps the load near 150 W in a 40 x 32 x 16 in box. When the computer makes more heat than the walls shed, stop sealing and filter the air instead. A filtered intake with media at twice the fan's open area keeps the flow and traps the grit. The numbers below give you the rise, the box size, the airflow and the filter area; the table at the end is what goes on the quote.
Do you seal the computer in, or filter the air through it?
Seal it when the machine runs fanless and its watts fit the wall — 66 W in a 24 x 20 x 10 in stainless enclosure, 174 W in a 40 x 32 x 16 in one, both at a 15 K rise over 25 °C shop air — and filter the air when the load runs bigger than that.
Sealing works because it removes the air path. Grinding and machining dust is steel grit, conductive once it settles across a live board. It hunts electronics the same way it finds a control cabinet in a dusty machining cell. A sealed enclosure with a gasketed door and gland-sealed entries gives the dust nothing to ride in on. The trade is thermal: every watt stays inside until the wall sheds it, so the machine you seal has to be fanless and its load modest.
Filtering keeps a standard tower breathing and moves the fight to the media. You keep the computer's own fans, add a filtered intake and a filtered exhaust, and clean the media on a schedule measured in weeks. What you give up is the sealed box's rating; the fan-opening section below prices that in.
A third build avoids the enclosure entirely. Extend keyboard, video and mouse over a CAT cable KVM extender, leave the tower in the clean office, and put only the console at the machine. For light lint in a quiet corner, a computer dust cover for a workshop is the cheap middle ground; beside a grinder it is not.
So the call comes out this way. Fanless machine at or under the wall's capacity, seal it. Standard tower or a hot machine, filter it. Console-only duty, extend it.
How much heat does your computer really put into the box?
Put a plug-in power meter on the computer, run a full work cycle, and read the watts at the wall: a desktop that idles near 40 W often peaks near 150 W, and that peak is the load the enclosure has to shed.
Every watt drawn at the wall turns into heat inside the box; a computer is a heater with a screen. The supply label flatters: a 450 W PSU rating is capacity, not draw, and this article's example machine is a tower that idles at 40 W and peaks at 150 W. Measure yours the same way, because the peak, not the idle, sizes the enclosure. A tower with a big graphics card draws several times the 150 W figure, and its own measured peak is the number to carry forward. Add the label watts of anything sharing the box with it: each 0.15 A fan at 12 V adds 1.8 W, and drives print theirs too.
What does a sealed enclosure do to that heat?
Inside a sealed box every watt leaves through the walls, and the temperature rise is watts divided by (3.7 x wall area in m²), where 3.7 W/m²K is the combined convection-and-radiation transfer figure for stainless.
For the example machine, 150 W in a 40 x 32 x 16 in (1016 x 813 x 406 mm) 304 stainless enclosure, the arithmetic runs:
- Wall area, all six faces: 2 x (1.016 x 0.813) + 2 x (1.016 x 0.406) + 2 x (0.813 x 0.406) = 1.65 + 0.83 + 0.66 = 3.14 m²
- Wall conductance: 3.7 W/m²K x 3.14 m² = 11.6 W per kelvin
- Rise: 150 W / 11.6 W/K = 12.9 K, call it 13 K
- Interior air: 25 °C shop + 13 K = 38 °C, under the 40 °C ambient most computers are rated for
A fanless industrial PC whose datasheet allows more than 40 °C only widens that margin; use the datasheet number in place of 40. Shrink the box and the same load stops working. A 16 x 12 x 8 in enclosure carries 0.54 m² of wall, 3.7 x 0.54 = 2.0 W/K, and 150 W drives it up 75 K, a build that fails at any shop temperature. Material moves the number the other way. Painted steel transfers at 5.5 W/m²K, so the same 40 x 32 x 16 in box in painted steel rises just 150 / (5.5 x 3.14) = 8.7 K; stainless trades a few kelvin for corrosion resistance.
How big does the sealed enclosure have to be?
Work backwards from a 15 K rise at a 25 °C floor — enough margin under the 40 °C interior limit — and a 150 W computer needs about 2.7 m² of wall, which is a 40 x 32 x 16 in enclosure or larger.
The table reads off the same formula, with wall areas for all six faces and the 3.7 W/m²K stainless figure. Use the 15 K column at a 25 °C floor and the 10 K column when the summer floor runs 30 °C; both columns hold the interior at or under 40 °C.
| Enclosure (H x W x D) | Wall area | Sealed load at 15 K rise | Sealed load at 10 K rise |
|---|---|---|---|
| 16 x 12 x 8 in | 0.54 m² | 30 W | 20 W |
| 24 x 20 x 10 in | 1.19 m² | 66 W | 44 W |
| 32 x 24 x 12 in | 1.86 m² | 103 W | 69 W |
| 40 x 32 x 16 in | 3.14 m² | 174 W | 116 W |
Put your measured peak against the rows and order the first size that clears it. The stainless wall-mount line spans 6 x 4 x 4 in to 60 x 36 x 16 in outside, and the custom service cuts any dimension in that span to your drawing, built from one piece. When the measured load tops the biggest row you can mount, the filter route further down carries it instead.
What rating and material should the sealed box carry?
Order 304 stainless for dry, dusty indoor air and 316L where cutting-fluid mist, brine or salt air wets the box, manufacturer-rated NEMA 4X / IP66 and not UL listed, because the first digit 6 is dust-tight and the Type 4X tests add corrosion resistance.
IP66 reads in two digits. The first-digit 6 means dust-tight: no ingress in the IEC 60529 dust chamber. The second-digit 6 means powerful jets, a 12.5 mm nozzle at 100 L/min, so the sealed shell also stands up to a hose at a washdown boundary. NEMA's Type-to-IP comparison (Table A-1 of its enclosure-types publication) puts Type 4 and Type 4X at the IP66 level, which is why one box carries both marks. Write the NEMA type on a US drawing, since NEC 110.28 is what an inspector there reads, and keep the IP code as the second mark. The IP rating chart and the NEMA 4 vs 4X vs IP66 comparison lay out the tests behind the digits.
On the door, an EPDM gasket seals dust and water from about -50 to 150 °C and takes washdown chemistry well; silicone covers about -60 to 200 °C where heat rules. Those are the ranges elastomer handbooks publish, and a named gasket datasheet wins where it differs.
Seal every cable entry like the door: compression glands matched to the panel cutout and the cable outside diameter, and no open knockouts under the backplate. How penetrations are sealed and sized on a rated box is its own subject; the NEMA enclosure penetrations: sealing rules, not 40% area page covers it.
How do you size the filter fans when the computer needs airflow?
Set the airflow with CFM = 3.17 x watts / rise in °F: a 150 W load held to a 10 K rise needs 3.17 x 150 / 18 = about 26 CFM, and the filter media should offer at least twice the fan's open area, about 10,000 mm² for a 120 mm fan.
The 10 K budget comes from the same interior limit: at a 30 °C summer floor, 40 °C minus 30 °C leaves 10 K, and 10 K is 18 °F. The formula is the standard air one behind the 1.08 BTU/h per CFM per °F HVAC constant. One healthy 120 mm fan covers the flow: spec sheets for that size commonly list 50-70 CFM free air.
The media is where filtered builds are won. A 120 mm fan's circle is 11,300 mm², and hub, blades and struts leave roughly 5,000 mm² of true open area. Media of twice that, about 10,000 mm² or a 4 x 4 in patch, spreads 26 CFM at a face velocity near 1.2 m/s, where pressure drop stays small and the fan keeps its curve. Media only the size of the fan doubles the velocity and the drop, and flow sags under it. Need more air? Add a second filtered intake, because parallel fans add flow; a push-pull pair on one opening does not.
Draw air in through the media rather than pushing it out through one, so leaks blow outward instead of pulling dust inward; the intake or exhaust decision has the reasoning. Pick media for the dust at hand with the air filter selection guide, size the package as a filter fan selection for panel cooling job, and let filter clogging monitoring set the cleaning interval before heat tells you late.
What happens to the enclosure rating once you cut a fan opening?
The fan-filter assembly becomes the weakest part and sets the rating: a NEMA 4X / IP66 enclosure with a filter-fan opening behaves as an indoor Type 12-type box, protected against dust, dirt and dripping liquids, and it gives up the washdown claim.
A box protects only as well as its lowest-rated opening, the principle that governs vents and drains too. A filter is a permeable membrane rather than a gasket: it captures what the air carries while admitting air, so the media itself sets the dust protection you get, below the IP6X dust-tight level.
In practice that means an indoor build. Filtered air keeps grit off the boards, dripping liquid stays out, and a hose blast drives water straight through the media, so keep filter-fan computers out of washdown cells and hose paths. Where the floor gets hosed down, the sealed build earlier in the page, or the KVM extension, is the route that holds its rating.
What goes on the order?
Send these lines and the built enclosure comes back delivered in 10 business days from your order, custom work counted from your approval of the drawing, with every rating and size below carried through the build.
| Order line | What to write |
|---|---|
| Material | 304 stainless, #4 brushed; 316L where cutting-fluid mist, brine or salt air reaches the box |
| Size | Pick from the heat table and order your own H x W x D, e.g. 40 x 32 x 16 in sheds about 174 W at a 25 °C floor; made from one piece |
| Rating | Manufacturer-rated NEMA 4X / IP66; not UL listed |
| Door and gasket | Hinged gasketed door, silicone or EPDM; removable mounting panel; wall-mount feet |
| Cable entries | Compression glands sized to cable OD (a PC power cord or Ethernet patch is near 6-8 mm); no open knockouts |
| Cooling, sealed route | None: fanless computer at or under the wall's watt row |
| Cooling, filtered route | Filtered intake with media at least 2x the fan's open area (about 10,000 mm² for a 120 mm fan) plus a filtered exhaust of equal media area |
| Lead time | Delivered in 10 business days; custom counted from drawing approval |
Pick the shell with the size finder, shortlist by environment and inside size with the enclosure selector, or send your own height, width, depth and cutout layout to the custom enclosures page from one piece.
Catalog dimensions to compare
Compare these catalog dimensions with your component layout. Open each enclosure for its rating, material and usable space, then check those specifications against your application.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 24 × 20 × 10 in | 304 stainless | 24 x 20 x 10 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 16 × 12 × 8 in | 304 stainless | 16 x 12 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 12 × 10 × 6 in | 304 stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 16 × 14 × 8 in | 304 stainless | 16 x 14 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does the NEMA 4X / IP66 rating survive the cutouts I add later?
It holds only when every opening seals like the door: a compression gland matched to the panel cutout and to the cable outside diameter keeps the dust-tight seal. A PC power cord or Ethernet patch sits near 6-8 mm OD, so M16-M20 glands with the right seal insert close on it; a grommet that merely lines the hole ends the rating on day one.
How often should filter media be cleaned on a grinding-heavy floor?
Start at a monthly check and watch the interior temperature. When the rise you designed, say 10 K, creeps toward 14 K at the same load, airflow is down about 30% and the media is loaded; clean it and shorten the interval. Soft lint buys weeks between cleans, sharp abrasive grit far less, so log the rise at every visit.
Can the computer keep its own case fans inside the sealed box?
They only stir the same sealed air, and each one adds its label watts to the load: a 0.15 A fan at 12 V adds 1.8 W for the wall to shed on top of the computer. Spec the machine fanless, with passive heatsinks or heat pipes, so the enclosure wall carries nothing but the computer's measured watts.
Is 316L worth the step up from 304 in a machine shop?
Yes wherever cutting-fluid mist or chloride deposits wet the box: 304 can pit at room temperature under wet chloride deposits, while the molybdenum in 316L raises pitting and crevice resistance. The chloride stress-cracking threshold near 60 °C (140 °F) applies to both grades. For dry, dusty indoor air with no chemistry in it, 304 is the right call.
Will a sealed enclosure condense on the inside overnight?
It can, when humid shop air is sealed in warm and the walls cool past the dew point overnight. Seal the box dry, then fit a 10-30 W anti-condensation heater, the range enclosure heater catalogs list for compact boxes, or a desiccant pack, so the walls sit a few degrees above the shop's dew point.
