How much clearance should a portable case PC cavity have?

Answer: Add 15 to 20 mm per side. Below 10 mm the foam is crushed; above 30 mm the machine slides.

Can foam thickness be judged by feel?

Answer: No. Work from the worst drop: 1.2 m needs 40 mm, 0.9 m needs 25 mm, 0.6 m needs 15 mm.

Is a more conductive ESD lining better?

Answer: No. Under ten to the sixth ohm it damages boards; above ten to the ninth charge cannot leave.

Above 15 kg, does the case still need a handle?

Answer: Yes, as secondary. On a portable case PC the wheels carry the load; the handle only lifts it over a step.

Can the pressure valve be deleted?

Answer: On short road legs only. On air freight the lid jams at 0.2 bar and forcing it stretches the gasket.

Portable Case PC Guide: Five Criteria Before You Buy

Quick answer: Buy a portable case PC by working backwards from the shipping conditions: cavity from the machine footprint, cushion from the worst drop height, an ESD lining with a stated surface resistance and a bleed path, then the handle and wheels, then gasket and valve.

Portable Case PC Selection: Order of Five Criteria
Cavity Size: Machine Footprint Sets the Case Class
Cushion Thickness: Working Back from Drop Height
ESD Lining: Surface Resistance and a Bleed Path
Handle, Latches and Sealing: Carrying Posture Sets Structure
FAQ

1. Portable Case PC Selection: Order of Five Criteria

You can shortlist whatever cavity looks good in a catalogue, or lay the machine and the shipping route on the table first.

Criterion	Locks down	A wrong call shows up as
Cavity clearance	Case class	Will not fit, or slides
Cushion thickness	Foam build, height	Corners fail first
ESD lining	Material, grounding	Faults after arrival
Handle, wheels	Carrying posture	Boss tears out
Gasket, valve	Air freight	Lid jams like a suction cup

Order matters: change the cavity and the foam and outer height move with it.

2. Cavity Size: Machine Footprint Sets the Case Class

A mid-tower desktop measures around 450 by 210 by 450 mm, a 24-inch monitor with stand near 560 by 340 by 60 mm.

Portable case PC: a sage-green case open on timber, a gasket groove on the lid, foam cut for a trowel, gloves and a green-handled tool

For a portable case PC, add 15 to 20 mm per side: past 30 mm the machine slides, below 10 mm the foam is crushed against a hard wall. Then allow 8 mm corner pads and 5 mm for ribs.

3. Cushion Thickness: Working Back from Drop Height

Air freight handling produces corner drops near 1.2 m, parcel sorting around 0.9 m, hand carrying 0.6 m. For a 500 mm cavity that is 40 mm of foam against 15 mm.

Thicker is not better: every millimetre adds height, weight and freight cost. Judge cushion by peak acceleration on a portable case PC, held under 40 G in a 1.2 m corner drop. PE at 30 kg per cubic metre survives repeated drops; EVA at 45 holds a crisp face.

Route	Drop height	Total foam	Build
Carried by hand	0.6 m	15 mm	Single PE layer
Single parcel	0.9 m	25 mm	PE with EVA facing
Air freight	1.2 m	40 mm	Double PE plus divider

Cut the pocket 2 to 3 mm shallower than the machine so the lid foam presses down and nothing drops out when inverted.

4. ESD Lining: Surface Resistance and a Bleed Path

Static protection is skipped because it shows up nowhere at goods-in. Mainboards tolerate discharges in the low hundreds of volts; two steps on a dry carpet build several thousand.

Portable case PC: a pale green case open on timber decking, pruning shears and cloth gloves inside, terracotta pots behind

Surface resistance should sit between ten to the sixth and ten to the ninth ohm: below that band the lining dumps the charge on contact, above it the charge sits there. Because PP and ABS are insulators, static needs a route out through metal latches or a moulded stud, under one ohm to the lining. Below 30 percent relative humidity ordinary foam climbs an order of magnitude.

5. Handle, Latches and Sealing: Carrying Posture Sets Structure

The fixing beats the shape: a through-bolted boss with a backing plate lasts longest, a self-tapping screw into a pocket comes second.

Up to 8 kg one moulded handle is enough, 8 to 15 kg needs a ribbed boss, above 15 kg the handle is secondary. Test at three times loaded weight, 30 kg for an hour.

Loaded weight	Posture	Structure
Under 8 kg	One hand	Moulded handle
8 to 15 kg	Hand plus strap	Ribbed boss, wheel option
Over 15 kg	Trolley	Twin wheels, handle secondary

Gasket and valve go together: an O-ring lid on a portable case PC jams on big temperature swings, so a valve cracks near 0.2 bar. Write minus 20 to 60 degrees Celsius into the order and prove it with a four-hour cold soak.

Conclusion

Specify cavity, cushion, static control, handle and sealing in that order, because each sets the next. Put those five numbers on the drawing and the sample approves in one round. Get the sequence right and a portable case PC stops being a guess.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.