Short answer: mount the PXI chassis in the standard 19 in [482.6 mm] rack pattern through its vendor rack-mount kit, and order the enclosure around your total U stack instead of hunting a fixed 6U box. EIA-310 gives every rack unit 1.75 in [44.45 mm] of rail height. Add the kit heights, add one spare U per powered unit, then size the box from the stack: width from the 19 in panel, depth from the chassis plus 4 in [100 mm] of clearance. The 14-slot system worked through below lands at 12 U, 21 in [533.4 mm] of rail height, and an internal 21 x 25 x 24 in box. That depth makes it a custom order, because the stock stainless line stops at 16 in [406 mm] deep.
The rack pattern the kit expects
Every 19 in rack follows EIA-310, with IEC 60297 as its metric twin: a 19 in [482.6 mm] panel, rails drilled 18.31 in [465.1 mm] apart, and 1.75 in [44.45 mm] of height per rack unit. The mounting holes climb in a 5/8 - 5/8 - 1/2 in [15.9 - 15.9 - 12.7 mm] cycle, so three holes carry one U. PXI chassis vendors publish rack-mount kits for exactly this pattern, and the kit's dimensional drawing gives you the two numbers the whole order hangs on: the kit height and the bolt spacing. Rails, shelves and PDUs in a full-height cabinet follow the same dimensions; the 19-inch EIA-310 rack setup guide walks the cabinet side of it.
| EIA-310 dimension | Value |
|---|---|
| Panel width | 19 in [482.6 mm] |
| Hole spacing across the rails | 18.31 in [465.1 mm] |
| Usable width between the rails | 17.7 in [450 mm] |
| One rack unit (1U) | 1.75 in [44.45 mm] |
| Hole pattern per U | 5/8 - 5/8 - 1/2 in [15.9 - 15.9 - 12.7 mm] |
Add up the U stack, then add spares
Count rail height, not slot count. PXI cards come in 3U [5.25 in] and 6U [10.5 in] heights and the chassis follow, so an 8-slot and a 14-slot chassis do not sort themselves by slots. Read each kit's dimensional drawing and list the heights. Then add one spare U for every powered unit: the chassis fans need intake room in front and the rear needs cable bend. The stack below is the worked example, a 14-slot chassis with a 3U panel power supply and a 1U vented shelf. Its kit heights are example values, and you replace them with the numbers printed on your kit drawings.
| Example component | Kit U | Rail height |
|---|---|---|
| 14-slot PXI chassis | 6 U | 10.5 in [266.7 mm] |
| Panel-mount power supply | 3 U | 5.25 in [133.35 mm] |
| Vented shelf | 1 U | 1.75 in [44.45 mm] |
| Spares, 2 powered units x 1 U | 2 U | 3.5 in [88.9 mm] |
| Total stack | 12 U | 21.0 in [533.4 mm] |
Size the enclosure around the stack
Work in internal clear dimensions and let the walls follow.
- Width: 19 in [482.6 mm] of kit ears plus 1 in [25 mm] of clearance each side = 21 in [533.4 mm] internal.
- Height: 21 in [533.4 mm] of stack plus 2 in [51 mm] below for gland entry plus 2 in [51 mm] above for a service loop = 25 in [635 mm] internal.
- Depth: 20 in [508 mm] of chassis and kit (the drawing's number) plus 3 in [76 mm] behind for connectors plus 1 in [25 mm] in front of the plate = 24 in [610 mm] internal.
Bolt the kit ears flat to the mounting plate at the 18.31 in [465.1 mm] spacing, on a plate at least 3/16 in [5 mm] thick so it stays flat when you seat a module. Outside, that stack wants roughly 24 x 28 x 26 in (W x H x D) once walls and feet are counted.
Depth is the buying decision. The stock stainless wall-mount line runs from 6 x 4 x 4 in to 60 x 36 x 16 in outside (H x W x D), so a 24 in [610 mm] internal depth goes past the 16 in ceiling. The box becomes a custom order: you set material, width, height, depth and every cutout. Check the stainless size finder if your rig is shallower and a stock size can carry it. Building several stands? Fix one outside size so panels and drawings interchange; the standard enclosure sizes article plans for that. For the general sizing fundamentals, the enclosure sizing guide covers wall loss and terminal bending space.
Heat decides sealed or ventilated
Take the heat load from your chassis datasheet; the example assumes a loaded 14-slot PXIe system at 300 W. Run the sealed case first. A 21 x 25 x 24 in internal box has about 2.1 m² of stainless wall, and stainless transfers k = 3.7 W/m²K, so the interior rises 300/(3.7 x 2.1) = about 39 K over ambient. At a 25 C [77 F] shop that is 64 C [147 F] inside, well past the 40 C [104 F] ceiling most electronics carry. The same box holds a 50 W load to about a 6 K rise, which stays under 40 C even at a 30 C [86 F] floor.
For a ventilated box, size the airflow from the load: airflow (m³/s) = watts / (1.2 x 1005 x rise in K). At 300 W and a 10 K [18 F] rise that is 300/(1.2 x 1005 x 10) = 0.025 m³/s, about 53 CFM [90 m³/h] through a fan-filter. Each extra 100 W adds about 18 CFM at the same rise, and a 100 CFM filter holds the example load near a 5 K rise. Let the chassis fans pull front to rear and keep the exhaust path clear.
Decision by load and site:
- Under about 50 W: seal the box and let the walls carry the heat.
- 50 to 500 W on a dry floor: fan-filter or blower sized by the formula; the blower cooling airflow article shows the full method.
- Washdown, brine or salt air: keep it sealed and move heat with an air-to-air exchanger matched to the load.
- The filter is the weakest part, and its rating becomes the assembly rating; match it to the box or accept the drop.
An outdoor stand adds sun load on top of the chassis watts; the outdoor rack computer enclosure article carries that arithmetic.
Rating and material by the site
The stand's location sets the type, and the type sets the material:
| Site | Type to order | Material |
|---|---|---|
| Bench or lab | Type 1 | 304 stainless or powder-coated steel |
| Factory floor, dust, oil mist | Type 12 | 304 stainless |
| Washdown, food, brine, salt air | Type 4X | 316L stainless |
| Outdoors, rain and sun | Type 3R or 4X | 304 or 316L, light-colored finish |
Salt, brine and chloride deposits go 316L, since 304 can pit even at room temperature where chlorides sit on the surface. Type ratings on these boxes are manufacturer ratings for the specified design: rated NEMA 4X / IP66 by the manufacturer; not UL listed. In US installations, NEC 110.28 keeps IP codes and enclosure types as separate marks, so a spec that calls for Type 4X needs the type written on the box. For what heavy dust does to a ventilated rack box, the two-rack-PC dust enclosure article is the cautionary case. To shortlist by environment, inside size and module count, the enclosure selector filters the catalog or carries the numbers to a custom quote.
What goes on the order
Send one drawing with the stack on it. The custom line builds from a single piece, we cut material, size and every hole from your drawing, and it delivers in 10 business days from your approval of the drawing. If the stand also takes an operator screen, put that door cutout on the same drawing; the door operator panel article shows how the cutout keeps the rating.
| Order line | Value for the example rig |
|---|---|
| Line | custom stainless enclosure, one piece |
| Material | 304 standard; 316L for washdown, brine or salt air |
| Type | Type 12 on a dusty floor; Type 4X for washdown (manufacturer-rated; not UL listed) |
| Inside size | 21 W x 25 H x 24 D in [533 x 635 x 610 mm] |
| Mounting | plate at least 3/16 in [5 mm], drilled for the kit ears at 18.31 in [465.1 mm] |
| Cooling | sealed under 50 W; otherwise a 53 CFM [90 m³/h] fan-filter at a 10 K rise (300 W example) |
| Cable entry | bottom glands sized to the cable |
Quote the kit drawing's bolt spacing with the order, because a spacing off by even 2 mm puts the ears under load when the screws go in.
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 |
|---|---|---|---|
| 60 × 36 × 16 in | 304 stainless | 60 x 36 x 16 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 48 × 36 × 16 in | 304 stainless | 48 x 36 x 16 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 60 × 36 × 12 in | 304 stainless | 60 x 36 x 12 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Is every PXI chassis a standard 19-inch rack unit?
Yes. PXI chassis vendors publish EIA-310-compatible rack-mount kits that land on the 19 in [482.6 mm] panel, with holes 18.31 in [465.1 mm] apart and 1.75 in [44.45 mm] of height per rack unit. The kit's dimensional drawing gives your chassis height and bolt spacing, and those two numbers start the enclosure size.
How many rack units does a PXI chassis need?
Read it from the kit drawing rather than the slot count. PXI chassis come in 3U [5.25 in] and 6U [10.5 in] heights, so an 8-slot and a 14-slot chassis can sit at either height. Add one spare U per powered unit; the example rig lands at 12 U, which is 21 in [533.4 mm] of rail height.
Can I keep a NEMA 4X rating with a fan-filter for cooling?
Only on a dry floor. The filter becomes the weakest part and its rating becomes the assembly rating, so a washdown Type 4X rig stays sealed and sheds heat through an air-to-air exchanger sized to the load. Ventilated indoors, about 53 CFM [90 m³/h] carries 300 W at a 10 K [18 F] rise.
What enclosure depth does a PXI test system need?
Chassis and kit depth plus 4 in [100 mm] of clearance: 3 in [76 mm] behind for connectors and 1 in [25 mm] in front of the plate. The example rig's 20 in [508 mm] chassis-and-kit depth lands at 24 in [610 mm] internal. The stock stainless line stops at 16 in [406 mm] deep, so this box is a custom order.
Why can I not just buy a fixed 6U PXI enclosure?
Because the stack rarely stops at the chassis. Six U is 10.5 in [266.7 mm] of rail height, but the example rig adds a 3U supply and 2 U of spares and lands at 12 U, 21 in [533.4 mm]. Size the enclosure to the stack and order one box with every cutout on a single drawing.
