“My product is waterproof.” Is it really?
Another day, another engineer talking about IP ratings... but this is what most websites won’t tell you.
Ed, the founder of Globex, recently gave a talk on some of the more interesting projects he’s worked on over the last 20 years. He touched on IP ratings, and that reminded me of four key things I’ve learned about IP ratings.
I won’t touch on the basics. (a good review of the IP rating system is here: https://www.iec.ch/ip-ratings)
1. If it passes IP67, it doesn’t necessary pass IP66
IP67 involves submerging a product under up to 1m of water for 30 minutes, and IP66 is a pressurized jet of water. Passing IP67 is a good thing – but it’s important to remember that a pressurized jet of water, with more localized pressure variation on a seal, is quite a different experience to submersion. This can mean you pass IP67, but counter-intuitively, fail the ‘lower’ IP66 spec. This same logic applies to more than just these two IP grades.
2. IP67 at room temperature, doesn’t mean IP67 at any other temperature
It’s tempting to run an IP67 (and ideally IP66 test) at lab conditions, per the relevant standards, and decide your product is ready for the market. But what if your product isn’t at lab conditions? If you submerge it in very cold water, perhaps the seal will shrink, or parts with different coefficients of thermal expansion will lead to gaps or warping. Even though the standards don’t require you to, it is critical to test at the real-world extremes your product will see.
3. IP67 on day one doesn’t mean IP67 after year one
Maybe you really are designing a piece of equipment that needs to be submerged in a sink for washing, but will otherwise never leave the lab – so you know it will never see extreme temperatures. But what if it gets dropped? What if it’s left in the sunlight and the UV exposure causes plastics to degrade? It is possible to repeat IP testing after impact or drop testing, and to expose your prototypes to a year’s worth of UV in a matter of days.
4. Rapid heating and cooling are the ultimate test!
IP69K (also known as IPX9K) is the highest IP rating, and the ‘K’ refers to elevated temperatures. Your room-temperature product will be sprayed with high pressure water at up to 80°C, and congratulations, you’ve passed the test – you have IP69K certification and a warm glow inside.
But is your device really waterproof? Imagine if you drop your now +80°C product straight into an ice bath. The rapid cooling of a sealed unit will lead to a pressure drop inside your device, doing its absolute best to suck the cold water into your product. Could anything like this happen to your product? If it could, you’d better design and test it accordingly.
In summary; IP ratings are not necessarily intuitive and they don’t mean your device is waterproof in all circumstances. As with most aspects of product development, it all comes down to understanding the environment around your device, and designing it accordingly.
Remember; if you don’t find what’s wrong with your product, your customers definitely will. Let us know if you’re having any sealing issues, we have plenty of experience with devices certified up to IP69K (and yes, we did cool it afterwards…).