2026-02-24 · Technical Insights

IP65/67/68/69K Is Not a Numbers Game: What Protection Ratings Really Mean

The IP rating (Ingress Protection) states a device's protection against solid foreign objects and water, and is a hard figure for whether a displacement sensor can run reliably for long in oily, wash-down or outdoor environments. IP65 / IP67 / IP68 / IP69K are not simply "the bigger the number, the higher the grade" — each digit corresponds to defined test conditions, and choosing wrongly costs you on site.

First digit: protection against solid foreign objects

Digits 0–6; 6 means completely dust-tight (dust cannot enter). The rod and electronics head of a magnetostrictive displacement sensor are usually dust-protected to IP6X, keeping metal swarf and oil sludge away from the waveguide.

Second digit: water protection

IPX4: protected against splashing water;
IPX5: protected against low-pressure water jets;
IPX6: protected against powerful water jets;
IPX7: protected against immersion (typically 1 m / 30 min);
IPX8: protected against continuous immersion (depth and time specified by the manufacturer);
IPX9K: protected against high-temperature, high-pressure jet wash-down, aimed at food and mobile hydraulic duty that needs frequent high-pressure washing.

Not a numbers game: test conditions at each level

Rating	Water-protection test conditions	Typical duty
IP65	Low-pressure water jets	General shop-floor splash protection
IP67	1 m immersion for 30 min	Short-term wading
IP68	Continuous immersion (manufacturer-defined)	Long-term shallow immersion
IP69K	High-temperature, high-pressure jet wash-down	Food / mobile-hydraulic wash-down

Engineering notes

IP69K ≠ an upgrade of IP67: the tests are entirely different; 69K is aimed at high-pressure, high-temperature wash-down, while immersion duty looks to 67/68;
The connector is the weak link: the sensor body may be IP69K, but water still enters if plug/cable protection is inadequate; fit a reliable M12 connector (see M12 connector maintenance);
Choose 69K for mobile hydraulic: for example the Series 13 mobile hydraulic type offers IP69K with vibration and shock resistance.

For wet marine and outdoor duty see marine displacement; hydraulic-cylinder application background is in hydraulic cylinder position control; protection in explosion-protected atmospheres is separately covered in explosion protection basics.

Practical tips for engineers

IP65 means a 6.3 mm nozzle jetting water from any direction has no harmful effect; IP67 means no harmful ingress under 1 m immersion.
Potentiometric sensors are typically only IP40/50, whereas non-contact magnetostrictive types can reach IP65 or even IP67 — in high-dust, high-humidity environments choose non-contact.