Does an IP67 portable protective box tolerate long immersion?

Answer: No. The test is 0.5 m for 30 minutes, so constant contact needs a replaceable gasket.

Where does the 1.2 m figure come from?

Answer: Weight bands, roughly waist height after a failed one handed lift.

What compression ratio should the gasket see?

Answer: 25 to 30 percent, measured before and after closing.

Does thickening corners add much weight?

Answer: About 90 g on a 12 litre body, going from 3.0 to 4.2 mm.

If pressure passes, is immersion still needed?

Answer: Yes. One lot passed pressure yet leaked at a corner, flash lifting the gasket 0.15 mm.

How to Choose a Portable Protective Box: Five Tests

Quick answer: Judge a portable protective box by five measurable things: drop height, corner wall, gasket compression, latch count and hinge pin, plus pressure and immersion results. When all five line up, the case survives 1.2 m and still holds -20 kPa.

Portable protective box ratings start at the wall
Drop height and corner travel
Gasket groove and pressure testing
Latches, hinge pin and handle load
Small batch acceptance and consistency
FAQ

1. Portable protective box ratings start at the wall

An IP number is what happens when three dimensions agree. Raise the wall from 2.0 mm to 2.8 mm and thicken the corner from 3.0 mm to 4.2 mm, and the same portable protective box passes a drop test the thin version fails.

Measure the long side, the short side and the base centre; a spread above 0.2 mm means uneven venting.

Rating	Seal	Wall	Corner	Use
IP54	EPDM single	2.0	3.0	indoor transfer
IP65	silicone with lip	2.5	3.8	light rain
IP67	twin gasket + vent	3.0	4.5	washdown

An R8 corner carries about 40 percent more stress concentration than R15 on concrete.

2. Drop height and corner travel

Drop height follows total weight, not a catalogue figure. Below 5 kg the portable protective box drops from 1.5 m, between 5 and 12 kg from 1.2 m, between 12 and 25 kg from 0.9 m, ten times over six faces, three edges and three corners. Peak acceleration inside must stay under 45 g.

Portable protective box: black moulded case open on pale grey, grey lid lining, two dividers splitting the cavity into three bays, two lens barrels inside

Foam travel sets that peak. An 8 mm gap lets the foam compress to 60 percent and absorb the most energy; squeeze it to 5 mm and the same drop lifts the peak from 45 g to 68 g.

Total weight kg	Drop m	Foam travel mm	Peak g
up to 5	1.5	10	40
5 to 12	1.2	8	45
12 to 25	0.9	6	55

Cold matters as well: after four hours at -20 degrees Celsius, PP impact strength falls about 40 percent, so the drop height is multiplied by 0.8.

3. Gasket groove and pressure testing

Sealing depends on compression. A 3.2 mm groove with a 4.0 mm cord lands at 25 to 30 percent compression once the lid closes, the groove 0.3 mm wider so the rubber can bulge. Under 20 percent rain finds a capillary path in twenty minutes; over 35 percent the cord takes a permanent set within a year.

Two tests are needed. Charge the closed case to -20 kPa through the vent, hold 60 seconds and lose no more than 1 kPa; then sink it to 0.5 m for 30 minutes with paper inside. A true IP67 unit also carries a vent passing about 200 mL per minute, or one air freighter leg flattens the gasket.

4. Latches, hinge pin and handle load

Latch count follows width: two below 400 mm, three between 400 and 600 mm, four above. Remove one and the lid middle lifts past a millimetre, exactly where the gasket stops working. Each latch should hold at least 220 N.

Portable protective box: slim black case open on pale grey, black foam lining the lid, a cylindrical gauge in a moulded recess, two front latches

A 5 mm stainless 304 hinge pin should stay within 0.3 mm of clearance after 20000 cycles; more slop shifts the lid and pushes the gasket aside. Handles take twice rated load for 30 minutes, and a PC latch that chips at -20 degrees belongs in PA66 with 30 percent glass fibre, at 0.8 CNY more.

5. Small batch acceptance and consistency

Sample to AQL 2.5, so 13 pieces from a 300 piece lot, and run all five checks; one failure sends the lot back.

Check	Condition	Pass if
Six face drop	1.2 m, ten drops	no crack
Pressure	-20 kPa, 60 s	within 1 kPa
Immersion	0.5 m, 30 min	no watermark
Latch retention	pull to release	at least 220 N
Salt spray	72 h	no red rust

Three production numbers matter. A single cavity tool on a 380 t press runs a 42 second cycle for roughly 2000 pieces a day; two cavities reach 55 seconds for 3100, but corner tolerance widens to 0.22 mm.

Conclusion

Choosing a portable protective box comes down to numbers anyone can check: a 2.8 mm wall or 2.0 mm, a 4.2 mm corner or 3.0 mm, a latch rated 220 N or 150 N. Those figures decide whether the interior holds -20 kPa after a 1.2 m drop, and they are where price gap and return rate hide. Written into the contract, they are why the portable protective box you receive still matches its drawing.

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.