How long can an IP67 case stay under water?

Answer: 30 minutes at 1 m on the rig. On a case that has been dropped and opened a few hundred times, plan on 20 minutes of margin.

Does seawater damage the rating?

Answer: Not the rating, but the hardware. Rinse for 5 minutes, dry, then close, and the latch springs last about two years longer.

Does a tighter latch seal better?

Answer: No. Sealing comes from 20 to 30 percent compression, and force above 120 N flattens the gasket and shortens its life.

Is IP67 the same as IPX7?

Answer: The second digit is. The 6 in IP67 is the dust rating, dust-tight; the X in IPX7 means dust was not tested. For water alone, both are 1 m for 30 minutes.

Should a new batch be tested?

Answer: Pull 3 units and run an air test at 20 kPa for 60 seconds, accepting 0.5 kPa or less before the batch enters stock.

IP67 Case: What 1 Metre for 30 Minutes Really Means

Quick answer: The 1 m for 30 minutes in an IP67 rating is a bench condition: the lowest point sits under a 1 m column of still water, the water is within 5 K of the case, and nothing moves. That is 9.8 kPa of pressure, less than a wave slaps on at a jetty. Pass or fail is judged on harmful ingress, not on water sitting on the outside.

Where the 30 minutes comes from
Four conditions on the rig
Sealing is compression, not latch force
Three things to do after immersion
Where IP67 runs out
Reading the test report
FAQ

1. Where the 30 minutes comes from

IEC 60529 states IPX7 plainly: immerse the sample in still water 1 m deep for 30 minutes, with the weakest point below 1 m, the top of the case at least 0.15 m under the surface, and the water within 5 K of the sample. A 1 m column of water is 9.8 kPa, or about 0.1 kg per square centimetre.

Those numbers describe what a hand can lift and a breath can hold, not the structural limit. An IP67 case will often survive 40 minutes at 1.2 m; the same case at 5 m may leak past a latch within 30 minutes.

Thirty minutes is a window, not a service life. After 26 drops from 1.2 m, lid and rim shift by up to 0.5 mm, part of the gasket now sits over a distorted face, and the next 30 minutes are a different test.

2. Four conditions on the rig

A rig holds four variables: water temperature, depth, time and attitude. Move one and the result cannot be quoted.

IP67 case seen from behind, arched handle folded down, red latch tabs at both top corners, twin skids under the base

Condition	Standard value	What drift does
Water temperature	Within 5 K of the sample	A cold bath shrinks trapped air and pulls water in
Depth	1 m at the lowest point	Measured to the handle, the base sits at 0.76 m
Time	30 minutes	Lifting the sample out restarts the clock
Attitude	Lid up, no rotation	On its side the gasket is in shear, a harsher case

Depth is the usual error. A 200 mm case with a 40 mm handle, measured to the top of the handle, puts the base at 0.76 m, 24 percent less pressure than the rating implies.

Temperature is the quieter error. A case packed in a 35 °C workshop and lowered into 15 °C water cools its trapped air over half an hour, creating roughly 2 kPa of negative pressure that draws water towards the seal.

3. Sealing is compression, not latch force

The gasket is 55 Shore A silicone, 4 mm cord in a 3 mm groove, closing to 3 mm for 25 percent compression. Below 15 percent it does not seat; above 40 percent it takes a permanent set within three months and recovers only 70 percent.

A thicker cord is not a better seal. The same 3 mm groove leaves a 3 mm cord with no compression, and a 5 mm cord reaches 40 percent, sealing once before it stops springing back. Keep the groove-to-cord ratio between 0.7 and 0.8.

Latches press the lid down; they do not seal. Two latches at 100 N each hold a lid gap under 0.4 mm, and a four-point layout evens the gap enough to drop each point to 80 N.

Item	Value	Acceptance
Gasket compression	4 mm cord closed to 3 mm	20 to 30 percent
Gasket hardness	55 Shore A	Rises no more than 5 points with age
Latch closing force	100 N per latch	80 to 120 N
Lid gap	Once latched	0.4 mm or less

An air test is faster. Pressurise to 20 kPa, hold 60 seconds, accept a drop of 0.5 kPa or less. On a failure, check the three points opposite the latches first, then the hinge side; those two areas account for about 70 percent of leaks.

4. Three things to do after immersion

Dry the outside first, especially around the lid gap. Then read the water marks: a line stopping outside the gasket groove is splash, a line inside it is ingress.

IP67 case at a three-quarter rear angle, red latches on the top corners, moulded back ribs, shadow on a white studio floor

Second, repeat the air test within 24 hours. A drop above 1 kPa means a new gasket, not a note for the next trip. Third, rinse for 5 minutes to move salt out of the latch springs, then let the gaps dry.

Salt spray attacks hardware, not the rating. After 48 hours of salt fog, even a stainless pivot shows pitting, while the case keeps its class.

A 5 g desiccant sachet and a humidity indicator card cost under 3 yuan, and the card answers the question before the next opening.

5. Where IP67 runs out

White-water immersion: entry pressure can reach 20 kPa, twice the 1 m static figure
Pressure washing: a 12.5 L/min jet at 30 kPa needs IPX6
Long soak: past 30 minutes the rating moves to IPX8, set by the maker, commonly 3 m for 60 minutes

Rating	Condition	Fits
IPX6	12.5 L/min for 3 minutes	Washdown, deck work
IPX7	1 m for 30 minutes	Falling in, short soak
IPX8	3 m for 60 minutes, maker-defined	Long immersion, recovery

One failure mode sits outside the scale: condensation. With a 20 °C day-night swing, the inner wall forms dew once a day and no ingress rating stops it.

6. Reading the test report

A usable report carries six fields: sample number, water temperature, depth, start and end times, verdict, and re-test result. Miss one and it is probably an in-house check.

Field	Acceptable wording	Common gap
Depth	1.00 m at the lowest point	1 m with no reference point
Water temperature	23 °C ± 2 °C	Temperature omitted
Time	30 min, with start and end	30 minutes only
Verdict	No harmful ingress	Written as no water enters

Watch the verdict wording. The standard says no harmful ingress and allows traces of moisture; a report promising no water at all has raised the bar above the standard.

Test 3 units from a batch and judge the worst one. A lid face flat within 0.2 mm gives repeatable results; past 0.3 mm the gasket cannot be compressed evenly.

Conclusion

The water resistance of an IP67 case is a set of conditions, not an adjective: 1 m, 30 minutes, 5 K, still water. Hold 25 percent gasket compression, a 0.4 mm lid gap and a 0.5 kPa drop at 20 kPa, and the claim becomes repeatable. Treat it as a test procedure rather than three characters on a label.

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.