If the first digit of the IP Rating is 6, is the case watertight?

Answer: No. That digit covers solid particles only, so an IP6X case takes water at 1 m because it was never immersed.

Can an IPX7 case be used in a dusty yard?

Answer: Not on the strength of that mark. X means dust was neither specified nor tested, so powder enters every joint.

Why do some datasheets show IPX7 instead of IP67?

Answer: Because only the water digit ran, so the dust position stays as X.

Does a 30 minute immersion replace a dust test?

Answer: No. Rigs, media and criteria differ, and 30 minutes of water produces no dust data.

Protective Case IP Rating: Dust and Water Tested Apart

Quick answer: An IP Rating always splits into two tests: the first digit measures dust at 2 kg/m³ and 20 mbar for 8 hours, the second measures water at 1 m for 30 minutes. A case marked IPX7 has never been dust tested.

One Code, Two Independent Tests
Dust Digits 0 to 6: Eight Hours of Talcum
Water Digits 0 to 9: Drips, Jets, Immersion
Write Both Marks: IP6X plus IPX7
Four Checks That Keep Digits Apart
FAQ

1. One Code, Two Independent Tests

An IP Rating is the letters IP, a first digit, a second digit and optional suffix letters. The first digit means solid particles and nothing else; the second means liquid and nothing else. IEC 60529 runs them as two rigs with two sample sets, so no dust result says anything about water.

Read the marking literally: IP67 is dust grade 6 plus water grade 7, while IPX7 leaves the dust position empty. X is not grade zero, it means the position was never specified.

The costliest mistake is treating one immersion result as a verdict on the whole case: grade 7 proves only that no water entered in 30 minutes at 1 m, while dust entry depends on gasket compression and latch count.

2. Dust Digits 0 to 6: Eight Hours of Talcum

The medium is talcum powder, not sand. The chamber holds 2 kg/m³ of powder with a median particle size near 75 μm, and the case interior is pulled 20 mbar below ambient for 8 hours.

IP Rating dust grade 6 is judged with the lid open: a white small plastic case lies closed on a white surface with two moulded latches at the front edge

Grade 6 is judged inside: wipe the shell, open the lid, inspect inner walls and each latch. No visible deposit is allowed beyond a 1 mm trace in the gasket groove. Grade 5 permits a little dust as long as it misses live parts.

Dust digit	What it covers	How it is run
1	Solids above 50 mm	50 mm sphere
2	Solids above 12.5 mm	12.5 mm sphere
3	Solids above 2.5 mm	2.5 mm probe
4	Solids above 1.0 mm	1.0 mm probe
5	Limited dust, no effect	Talcum 2 kg/m³, 8 hours
6	No dust entry	Talcum 2 kg/m³, 20 mbar, 8 hours

Digits 0 to 4 need only a sphere or probe and return in a day; only 5 and 6 need the chamber. Grade 6 adds a double gasket and a 3.2 mm lid lip, lifting price 15% to 25%.

3. Water Digits 0 to 9: Drips, Jets, Immersion

Digits 1 and 2 drip at 1 mm/min onto a turntable at 1 r/min for 10 minutes, grade 2 tilting the case 15°. Grade 3 is an oscillating tube of 200 mm radius; grade 4 splashes 10 L/min from a 6.3 mm nozzle.

Grades 5 and 6 are jets: 6.3 mm at 12.5 L/min and 30 kPa against 12.5 mm at 100 L/min and 100 kPa, each for 1 minute per face. Grade 7 is the first immersion grade, 1 m for 30 minutes; grade 8 is continued immersion by agreement, often 1.5 m; grade 9 is an 80 °C jet at 80 to 100 bar.

Water digit	Key parameters	Duration
1	1 mm/min drip	10 minutes
2	1 mm/min, 15° tilt	2.5 minutes per face
3	0.07 L/min per hole	10 minutes
4	6.3 mm nozzle, 10 L/min	5 minutes minimum
5	12.5 L/min, 30 kPa	1 minute per face
6	100 L/min, 100 kPa	1 minute per face
7	1 m below surface	30 minutes
8	Depth by agreement	Often 1.5 m, 30 minutes
9	80 °C, 80 to 100 bar	Per agreement

Two misreadings persist. Grade 6 sounds violent at 100 L/min but lasts one minute per face, so it never proves a case can be submerged; grade 7 stops at 30 minutes.

4. Write Both Marks: IP6X plus IPX7

IP67 is complete under the standard yet degrades in a contract, because a supplier can deliver one water report and write exempt on the dust page. Splitting the mark into IP6X and IPX7 on separate lines removes that gap.

Order wording	Exposure
IP67	Two pages needed, easily merged into one
IP6X plus IPX7	Clear clause, checked page by page
IPX7	Dust enters freely, the marking hides it
IP6X	Fails at the first standing water
IP65	Rain fine, dropping in water is not
IP54	Splash only, never wash down

Splitting also makes quotes comparable: dust plus immersion needs six cases in total, so a quote budgeting three has dropped one rig.

5. Four Checks That Keep Digits Apart

Never judge a report by its conclusion page, which only says compliant with IP67. The item table should hold two records, one for dust with powder type, vacuum and duration, one for water with depth, duration and orientation.

IP Rating checks look at orientation: a blue small plastic case lies closed on a white surface with two moulded latches engaged and a curved handle recess

Read the test basis. The front page must cite IEC 60529 and list both digits.
Check the sample build. Wall thickness, gasket hardness and latch count must match production, or a lid lip cut from 4.5 mm to 3.8 mm hides behind a stale report.
Demand photographs. Dust reports should show the cavity after opening; water reports need the depth scale.
Set a retest interval. Retest water at 24 months and let dust run to 36 months.

One item is easy to miss: a pressure equalisation valve has a membrane with a pore size, so both marks must run with it fitted.

Conclusion

Keeping the two digits apart is the cheapest audit step in case procurement. Write IP6X and IPX7 on separate lines of the technical clause, demand one photographed report each, and read results against the rig rather than the label: talcum at 2 kg/m³ and 20 mbar for 8 hours, water at 1 m for 30 minutes. Insist that samples match production wall thickness and gasket hardness, because a report from a heavier build describes a case nobody will receive.