The Ingress Protection Rating

by conradb212

About ruggedness testing and why the ingress protection rating of mobile computers is especially important

What sets rugged handheld computers and tablets apart from standard consumer products is their ability to take the kind of punishment that comes with using a device on the job and in the field where conditions can be harsh.  As a result, the specification sheets of virtually all rugged devices include the results of certain ruggedness tests. How much of that data is supplied varies from manufacturer to manufacturer. It can be very comprehensive or just touch upon the basics.

There are arguments to be made for both approaches – a lot or just a bit. Ruggedness testing data can be very dry and not always easy to interpret. “Operating 10 G peak acceleration (11 ms duration),” for example, doesn’t easily convey how much shock a device can handle before it breaks. Or it can be too vague, like “MIL-STD-810H compliant,” where said standard is over a thousand pages of densely packed tech info, and simply referring to it doesn’t say anything.

There is, however, a happy medium – device specs that include the few items that matter most, and then have more comprehensive data on file for customers who ask for it or really need it. But what are those few specs that really matter? The general answer is, as is so often the case when it comes to ruggedness – it depends. If you work in or around commercial freezers and need to use your device all day long, you need to know what temperatures it can handle. If you’re a pilot and fly unpressurized planes, you need to know if air pressure differences are an issue. If you work at a port or in a boat, salt fog resistance is important. And so on.

Of all the ruggedness specs, there are two that matter most and are of most importance to almost every user.

One is the “drop spec,” i.e. from what height can a device be dropped and still survive the fall unharmed. Virtually every device will be dropped at some point, and so the drop spec matters. What should that height be? That depends on the device. A handheld computer will most likely be dropped using it while holding it in one’s hands, and that’s generally about four feet. A smartphone may be dropped while holding it to one’s ear. So that’s five or even six feet.

The other is “ingress protection” – whether a device leaks. The rating is given as a two digit number, for example, IP52 or IP67. Like almost every standard, ingress protection is defined in a very technical publication, here in international standard EN 60529 (British BS EN 60529:1992, European IEC 60509:1989). Wow. And you can’t just look up the standard and read it. So let’s talk about the IP rating a bit.

In essence, the rating is used to define the level of sealing of electrical enclosures against intrusion by foreign bodies, like tools, dirt, and dust in the first number, and moisture and liquid in the second. How are those levels of “intrusion” defined?

On the solids side there are six levels. They range from protection against large physical objects like hands or other solid objects more than two inches in diameter, all the way to being completely dust-tight. For handheld computers, levels 1 through 4 hardly ever apply, because there are no open holes to the interior. Levels 5 and 6, however, do matter. 5 is partial protection against harmful amounts of dust getting in, and 6 means no dust is getting in at all.

On the liquids side it’s a bit more complicated. There are nine levels on that side, and all can apply to handheld computers. The lowest protection level – 1 — guards against vertically falling droplets getting in, like rain or condensation dripping. The highest level – 9 – means protection against the kind of high-pressure, high-temperature jet sprays used for wash-downs or steam-cleaning procedures. In between are seven levels of increasing protection against water drops, splashes, low and high pressure jets from various angles, and then on to complete immersion for certain amounts of time and pressure.

So far so good, and for the most part this rating system makes sense. I say “for the most part” because, like many such systems and documents, the EN 60529 ingress protection rating standard covers a very broad range of items, ranging from very small to very large. That means that some rating levels may apply to some electrical items but not to others. For example, both on the solids and liquids side, some of the levels may allow “limited ingress” or “partial  protection,” which may be okay for some gear but not for others. For example, a little bit of water getting inside a massive piece of equipment may be of no consequence, whereas for a small item like a watch or a handheld computer it’d be fatal for the device.

Now let’s take a look at the range of IP ratings for different types of rugged mobile computers.

Ruggedized  laptops generally fall into one of two classes, semi-rugged and fully rugged. Most semi-rugged laptops used to have either no rating or an IP5X rating. 5 means partial protection against harmful dust getting in and X means no protection. That has gradually changed over the past few years, with semi-rugged laptops from leading vendors now carrying IP53 protection —  partial protection against harmful dust, and protection against water spray up to 60 degrees from vertical, which pretty much means getting rained on. Fully rugged laptops from leading providers now generally carry IP65 protection, meaning they are totally dust-tight and can also handle low pressure water jets from any angle. The latter albeit with the dreaded “limited ingress permitted with no harmful effects” qualifier that is entirely relative.

Ruggedized tablets also come in semi-rugged and fully rugged versions, but the terms aren’t used as rigidly as with laptops. It’s also easier to seal tablets because they have neither a keyboard nor as many ports as laptops. That said, a tablet considered “semi-rugged” may have an IP54 rating — partial protection against harmful dust and protected against water splashes from all directions. Fully rugged tablets should have at least an IP65 rating – totally dust-tight and able to handle low pressure water jets from any direction. But to stand out, an IP67 rating is necessary. That means totally dust-tight and able to handle full immersion for a limited time and depth. That’s because laptops rarely fall into a puddle or pool, but with tablets that can happen.

Rugged handheld computers require higher ratings yet. They can go anywhere and are being used anywhere. Which means they may dropped anywhere and can fall into almost anything. That means at least an IP67 rating: totally dust-tight and protected against full immersion. A few years ago IP67 was still rare with rugged handhelds. Now it is, and should be, the minimum requirement. And it is what most of the leading providers of such handhelds offer.

What about IP68 and IP69? IP68 comes in where IP67 is too limiting – on the liquid side IP67 “only” requires being able to handle full immersion for up to 30 minutes and depths no more than a meter (3.3 feet). It’s quite possible for a handheld to exceed those limits in an accident, and it’d be good to have a bit more leeway to retrieve expensive equipment before it is destroyed.

That’s where IP68 comes in. It provides protection against longer and deeper immersion. The caveat here, though, is that it’s up to the manufacturer to decide how long and how deep. That is causing many less reputable outfits to claim IP68 protection without explaining the testing parameters. And the vagueness isn’t limited to just questionable sources. Apple, for example, claims their late model Apple Watches have a water resistance rating of 50 meters (164 feet) under ISO standard 22810:2010, but qualify that by saying the watches are water-resistant but not waterproof, and that even water resistance may diminish over time. So it’s “caveat emptor” in many cases – the buyer is responsible to figure out what the claim means.

IP69 really shouldn’t be on this scale, as it is mostly used just for specific road vehicles that need to be hosed down with high-pressure, high-temperature jet sprays. So IP69 doesn’t mean it’s better than IP68; it’s a different type of rating and rarely applies to mobile devices.

All the above said, it should be clear by now that IP ratings matter. Ignoring them can mean instant damage or destruction by not observing the limits. If you sit an IP5X laptop into a puddle of water it’s most likely light-out for the device.

Even with suitably high ratings it pays to apply common sense. Just because a device is rated capable of handling certain exposure doesn’t necessarily mean you should be careless or test the limits. That’s because, as Apple points out with the watch, “water resistance may diminish over time.” That can happen when seals age or get damaged, protective port covers and plugs are not properly closed and locked. And even when common sense suggests that one better not put a claim to the test.

So that’s the deal with Ingress Protection. Dust and liquids don’t go with electronic gear. Keeping them out matters. And the IP rating tells you how protected your device is. Do pay attention.

Comments |2|

Category: Editor