IP65 vs IP67 vs IP69K: choose by cleaning method, not number size

Three quotes land with lights marked IP65, IP67 and IP69K, and the biggest number looks like the best light. It is not. Each code records a different liquid test, and a light can pass immersion while failing a plain hose spray. This guide reads the two digits under IEC 60529, puts a pressure figure behind every rating, and maps all three onto the cleaning methods that actually decide the choice: wiped, splashed, dunked, hosed, washdown. By the end you can specify the digit from the cleaning schedule alone.

The two digits are separate tests

The code is defined by IEC 60529; the IEC's IP ratings page keeps the official summary. The first digit grades solids. 6 means dust-tight, proven by eight hours in a circulating talcum-dust chamber under slight vacuum with zero ingress. 5 means dust-protected: some ingress is allowed as long as it never interferes with operation. For vision lights the difference is mostly conductive powders, flour and sugar dust reaching the LED board.

The second digit grades liquids, and this is the trap: the tests are independent results, not a ladder. The standard notes that a numeral 7 result does not by itself demonstrate numeral 5 or 6 — the Wikipedia entry on the IP code tabulates each test — so an enclosure that passes several digits must list them all. A sheet reading IP67 says nothing about jets, while an IP65 light already carries a jet test the IP67 unit never ran.

For the digit-by-digit reading on lights, see IP ratings for machine vision lights: read the digits first.

What each liquid digit puts the light through

Digits 5, 6 and 7 come from IEC 60529. The 9K digit has a different pedigree: written as DIN 40050-9 for road vehicles that get steam-jetted clean, later folded into ISO 20653, then adopted by food and pharmaceutical plants as the washdown grade. Thirty seconds per angle is all a seal gets to prove itself against an 80 °C lance at close range, so the K rating is about jet survival, not general toughness.

Worked example: IP67 at 1 m of water against an IP69K jet at 80 °C

Inputs, and where each comes from: h = 1 m and t = 30 min from the IEC 60529 immersion method for IPX7; ρ = 1,000 kg/m³ for plain water and g = 9.81 m/s² from physics; jet pressures of about 30 kPa for IPX5 and 8,000–10,000 kPa (80–100 bar) at 80 °C for IPX9K from the test conditions above.

The rule in words: static pressure under water grows with depth, so multiply density by gravity by depth.

Result: the seals of an IP67 light qualify under about 9.8 kPa — a tenth of a bar — of static head.

Compare like with like. The IPX5 jet carries roughly 3× that head (30 kPa / 9.8 kPa ≈ 3.1). The IPX9K lance carries roughly 800–1,000× the immersion head (8,000–10,000 kPa / 9.8 kPa ≈ 815–1,020) and about 270–330× the IPX5 jet (8,000–10,000 kPa / 30 kPa ≈ 267–333). The digits form no ladder because the tests share no single quantity.

The decision: wipe-and-splash cells can run IP65 or IP67 with equal honesty; the moment a lance or pressure washer reaches the light you need a jet digit — IP66 for cold heavy jets, IP69K for the hot washdown. Above roughly 30 kPa of jet pressure, an IP67-only light is unqualified by its own certificate.

Pick the digit from the cleaning schedule

One question decides the code: what liquid reaches the light, how hard, how hot, how often.

Dry and dusty: IP65 already proves a dust-protected housing plus a 30 kPa jet from any direction. Step to IP66 when the powder is conductive or the hose is stronger.

Washdown food and pharma: IP69K is the working answer, and the rest of the selection — window material, mounting angle, strobe — follows the food washdown vision lighting checks.

Middle case, heavy cold jets without heat or chemistry: IP66. That trade-off recurs anywhere tunnels and continuous washers spray sensors and lights; the same logic is worked through for tunnel sensors in IP65 vs IP66 selection for cleaning.

Shortlist the lights in the lights finder or start at the light step of the configurator.

What no digit covers

Every IP code tests water against an assembled, new enclosure. Four things sit outside it.

Chemistry. Oils, lubricants and water-based coolants attack seal compounds that water never bothers, so an IP69K light can still leak over a machining center. Keep optics above the mist line and match the wet chemicals to the materials named on the data sheet.

Weather. UV, freeze-thaw and daily thermal swings are tested by no digit, so a code never makes a light outdoor-rated. If the camera is the harder problem, housing a bare stereo camera for the outdoors walks through it. IP codes also do not convert into NEMA types: a NEMA enclosure rating additionally runs corrosion, gasket-aging and ice tests that IEC 60529 never attempts, so an IP code never proves a NEMA type.

Time. The certificate describes the product as delivered. Gaskets compress, glands relax, drain holes clog; keeping the rating is a maintenance job, and how manufacturers hold enclosures at their rated IP level shows the factory-side discipline to mirror on your line.

Hot jets. IP69K proves the seal survives the lance. It does not certify the optics, the cable, or your caustic, and the gaps are catalogued in IP69K washdown lighting: what the rating does not cover. Cameras carry their own set, covered in getting an IP65 rated camera for washdown.

Where the light controller sits in a wet cell

The rating belongs to the light; the light controller lives in the cabinet. That split is deliberate. Strobing from a dry cabinet pulses the LEDs only during exposure, which cuts heat and seal stress and lets you drive harder pulses for a freeze-bright image. Get the trigger chain right first: camera strobe output timing shows how the exposure pulse and the image timestamp line up.

For channel counts, the LS-CTL-0070 is the usual pick: four channels at 200 W total, strobe control and RS-232, one box for a ring, a bar and a backlight in a hosed cell.

Brightness stability matters as much as sealing, because thresholds drift when LED output sags with temperature. Constant-current channels hold output flat from cold start to running temperature, and the LS-CTL-0180 does that across four channels at 120 W for 24 V lights in an 89 x 147 mm housing.

For large strobed backlights, the LS-CTL-0264 switches two channels at 400 W with a network option for remote line control.

Size each channel to the lights' rated current and voltage, keep light cable runs short, and pick the rest at the controller step of the configurator.

Checks before you order

• Read both digits off the data sheet itself, not the quote header: listing titles round down as often as up.
• If you terminate the light cable yourself, use the entry the maker documents for that rating. A field-made hole resets the whole housing to the worst new leak path.
• Rate every entry, not just the housing: a connector rated IP67 on an IP69K light caps the assembly, because ingress takes the weakest path.
• Name the chemistry — caustic foam, sanitizer, coolant — since the IP test ran with water only.
• Plan strobing and cabinet placement before install; a controller on the wet side of the wall is the mistake that never gets fixed.
• Outdoors, ask for a stated weathering rating rather than a bigger digit.

When the bigger digit is the wrong answer

Three specifications that fail most often, in order:

IP67 chosen over IP65 or IP66 for a hosed cell. The buyer read 6 as better than 5 and dropped the jet test the line runs every shift. IP65 would have passed.

IP69K specified for a dry cleanroom. The line pays for a hot-lance qualification it never runs and inherits a light built for chemistry it never sees. IP65 is the honest spec there.

IP68 assumed to be washdown. The depth and duration are agreed per product and printed on the data sheet — commonly deeper and longer than IPX7's 1 m and 30 minutes — with no jet and no heat test. A pressure washer defeats a deep-diver seal that has never met a lance.

Write the cleaning method into the spec next to the digit and the wrong box never ships. More lighting selection guides sit on the lighting topic page; for a washdown quote, send the cleaning chemistry, cycle and standoff distance through the contact page.