Is a higher IP rating always better for an equipment protection case?

Answer: No. A tighter seal makes pressure and condensation worse. Match the rating to the dust and water on site.

Can dust still pass a vent?

Answer: A little can. The membrane blocks particles above its pore size, but dust on the sealing face can enter during service.

Is thicker foam always better?

Answer: No. Foam pressed into densification has no travel left and raises the g. Two to three millimetres of spare compression is the test.

How much desiccant is enough?

Answer: Estimate by lid cycles. Each exchange adds about 0.24 grams of water, so five grams covers roughly twenty openings.

Can all three defences be maximised at once?

Answer: No. They compete for one volume and one seam. Fix the weakest point first, accept margin on the rest.

Equipment Protection Case: Impact, Dust and Moisture

Quick answer: An equipment protection case works on three routes rather than three materials. Impact arrives through solids and is limited by usable travel; dust arrives on air and is limited by gasket squeeze and a vent; vapour arrives inside the air and is limited by cavity volume and desiccant mass.

What an Equipment Protection Case Blocks
Impact: Turning Drop Height into Deceleration
Dust: What the Two Digits Separate
Moisture: Where Condensation Comes From
When the Defences Conflict
FAQ

1. What an Equipment Protection Case Blocks

The shell gives the product its shape; protection comes from the layers inside it. Each hazard uses a different route, so each needs a different dimension. Impact is measured in millimetres of usable travel, dust in gasket squeeze, moisture in grams of water per cavity volume.

None of the three is visible from outside, which is why a case can look robust and still fail. Thick walls do nothing for a load clamped to a hard divider, and a wide gasket fails in a shallow groove.

Hazard	Route in	What the drawing fixes
Impact	Base, through the liner	Foam travel and compression ratio
Dust	Gaps, carried by air	Gasket squeeze and vent path
Moisture	The air itself	Cavity volume and desiccant mass

2. Impact: Turning Drop Height into Deceleration

An eight kilogram unit dropped 1.2 metres lands at 4.85 metres per second with about 94 joules. Spread over 40 millimetres of foam travel that is near 30 g; halve the travel to 20 millimetres and it doubles to 60 g. Travel decides the outcome, not wall thickness.

Compression ratio decides how much travel remains. Ten percent behaves almost rigidly, forty percent densifies and the force climbs. Stay between twenty and thirty percent with two to three millimetres spare, and treat a heavier payload as a new liner, not a thicker shell.

Device mass	Energy at 1.2 m	Deceleration, 40 mm travel
4 kg	47 J	about 30 g
8 kg	94 J	about 30 g
16 kg	188 J	about 60 g as travel shrinks

3. Dust: What the Two Digits Separate

The first digit covers solids and the second covers liquids. Level 6 is verified in a chamber holding 2 kilograms of talc per cubic metre under a 2 kilopascal vacuum for eight hours, then the interior is inspected. A cloth proves nothing.

Dust enters on pressure difference rather than through a visible gap. A warm case or an unheated cargo hold can put 0.1 bar across the gasket, lift it and draw dust inside. The vent exists to give that air a filtered path.

Seal location	Failure mode	Field check
Lid corner	Contact line breaks at the radius	Feeler gauge, lid closed
Vent membrane	Clogged, no longer breathes	Hold to the light
Hinge boss	Bore becomes a bypass	Seal bore, retest

4. Moisture: Where Condensation Comes From

At 30 degrees Celsius, saturated air holds about 30 grams per cubic metre, so a ten litre cavity at eighty percent humidity carries only 0.24 grams of water. Cool it by 15 degrees and relative humidity more than doubles, enough to reach the dew point on metal.

Size desiccant by lid cycles, not by months. Each opening brings back roughly 0.24 grams, so five grams of silica gel covers about twenty exchanges. A case opened daily needs a smaller cavity and a shorter open time, not a larger sachet.

5. When the Defences Conflict

A tighter seal raises the pressure difference, so the vent has to open, and the membrane becomes the only barrier to water. Thicker impact foam shrinks the cavity, so the same electronics warm the air faster and condensation arrives sooner.

Rank by the weakest point of the device. Shock first means low-density foam and soft edge stops; dust first means gasket squeeze and valve filtration; humidity first means smaller volume and desiccant on the coldest face. When all three matter, the case usually goes up one size.

Conclusion

The product blocks routes, not substances: impact through solids, dust through gaps, vapour through the air itself. Convert each route into travel, squeeze and grams, and protection stops being an argument about wall thickness. Once those numbers are fixed, colour and hardware are details, which is the order a competent equipment protection case is built in.

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.