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Degrees of Sealing: Designing Rugged, Waterproof Enclosures for Electronic Devices

Electronic devices today are expected to go where they’ve never gone before. Thanks to advancements in sensor technology and IoT, users want to put rugged sensors in more and more rough environments, and they often expect them to live outdoors and underwater.

While consumers used to assume electronics couldn’t get wet, that’s no longer the case. Today’s consumers are accustomed to swimming and skiing with wearable tech, or keeping their phones in their pockets at all times, whether they’re on a beach vacation or a sweaty jog.

In these environments, electronic devices are exposed to liquid, introduced to dirt and dust, and expected to bounce back when they fall. As a result, the demand for waterproof and rugged consumer and commercial products is growing. Users expect their products to be just as rugged and waterproof as they themselves are.

The demand for waterproof and rugged consumer and commercial products is growing.

The catch is that “rugged” and “waterproof” are, for the most part, just vague marketing terms, and many companies use them liberally. While a “waterproof” device might withstand some light rain or splashing liquid, being submerged underwater is another story. Knowing just how waterproof or rugged products are is a challenge for both the companies designing them and the consumers buying them.

That’s where rating systems come in.

Ingress Protection (IP Ratings) for Product Design

There are three main rating systems that determine how waterproof or rugged a product is: Ingress Protection (IP) Rating, NEMA Rating, and MIL-SPEC. These help quantify how much liquid and/or solid material — dirt and dust — can enter a product given its sealing, and MIL-SPEC takes bumps and falls into account.

These rating systems are really parallel but are targeted at different industries. In product development, we tend to use IP Ratings. NEMA (National Electrical Manufacturer Association) Ratings are generally used for electrical enclosures such as large industrial automation enclosures. And MIL-SPEC tends to focus more on drop-testing for products like Panasonic’s Toughbook, a Windows® notebook advertised to withstand falls and rough handling.

To help our customers decide which standard to use, we look at the industry they’re in and similar products on the market.

Understanding the IP Rating System

IP Ratings are part of an international classification system meant to specify how well a product’s sealing keeps solid objects and water out of electrical enclosures.

IP Ratings are listed as IP, followed by two digits: An example would be IP32 or IP67. The first digit correlates to how protected a device is against physical objects, like dirt and dust. The second describes how protected the device is against liquids.

Each number is determined by specific testing standards. IP32 must keep out solid objects greater than 2.5mm in diameter, such as a screwdriver (3), and be protected from vertically falling water tilted up to 15 degrees from the vertical (2).

One product we worked on was the Scott Protégé, a handheld toxic and combustible gas monitor. It needed to be sealed to IP67 requirements, meaning it needed to be protected against dust intrusion (6), and it needed to be protected against submersion in water, up to 1 meter for 30 minutes (7).

IP Ratings in the Real World

Another product we worked on was the Nielsen-Kellerman Blue Ocean Megaphone, a digital megaphone used by rowing coaches. These megaphones live on boats and docks. They get rained on, splashed on, even dropped in the water, so they need to be sealed tightly.

The NK Megaphone presented a few sealing challenges. We needed to be able to change batteries; and we needed sound to travel into a microphone and out through a speaker.

We worked with NK to determine that IP67 would be the optimal rating, meaning it would be sealed against dust and would function after being submerged in water up to one meter deep for 30 minutes. The design was so successful that, when one of the megaphones washed away and was found months later during a wetlands cleanup, it still worked!

Understanding the NEMA Rating System

While most consumer products use the IP Rating System, the NEMA Rating System is more appropriate for electrical enclosures. Developed by the National Electrical Manufacturer Association, NEMA Ratings generally cover more industrial products and go a few steps further than IP Ratings.

While IP Ratings consider dust and water intrusion, NEMA also factors in ice, corrosives, and oil, as well as construction details.

NEMA Ratings range from NEMA 1, products intended for indoor use that provide a degree of protection to personnel from shock and protection against a limited amount of falling dirt, to NEMA 13, products intended for indoor use that provide a degree of protection against dust, spraying water, oil, and non-corrosive coolant. NEMA 3, 3R, and 3S specify standards for outdoor products, and NEMA 4 specifies standards for products that might be washed with high-pressure water or chemicals.

Companies looking to use NEMA Ratings should first consider if their product is intended for indoor or outdoor use, what elements it will be exposed to, if it will be hosed down, and if it will be exposed to corrosive agents or oil and coolant seepage.

Understanding MIL-SPEC Ratings

The third rating system, MIL-SPEC, also goes by military standard, MIL-STD, or MilSpecs. It was first developed by the military around World War II, when the Air Force detailed how equipment should be tested, and it has been evolving ever since. Today, MIL-SPEC is used by the U.S. Department of Defense and by private companies looking to demonstrate product durability.

MIL-SPEC Ratings are used to test a product’s design, materials, manufacturing, and maintenance, to show that it will withstand its environment and intended lifecycle. It takes altitude, temperature, rain, humidity, fungus, salt fog, sand and dust, explosive atmosphere, leakage, acceleration, transport, and vibration into account.

MIL-SPEC was first developed by the military around World War II, when the Air Force detailed how equipment should be tested, and it has been evolving ever since.

A MIL-STD 810F rating, for example, indicates a product can be dropped on a concrete floor from six feet, withstand wind and rain for an hour at 200 millimeters per hour, withstand vibration for 18 hours, and function after three hours of sand and dust exposure at up to 18 meters per second.

Buyer and Manufacturer Beware

These rating systems help indicate a level of sealing that’s more specific than “waterproof” or “rugged,” but they’re not perfect. For starters, nobody is regulating products to say, yes, this meets the standard listed. There are labs that will test products, but many products are self-tested, and a lot of product developers only test one or two products — which is not necessarily conclusive.

Just like “waterproof” and “rugged,” these ratings can become marketing terms, and in some cases they range from optimistic to downright lies. When we perform product teardowns and industry benchmarking, it’s not uncommon for competitors’ products to fall short of their specs and marketing claims.

On one hand, IP, NEMA, and MIL-SPEC can act as tools to help manufacturers seal and test products to ensure they’ll meet lifecycle requirements, and the ratings help consumers understand just how rugged and waterproof a product is. On the other hand, it’s still up to brands to uphold their integrity, and it’s up to consumers to do their research.

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