MIL-STD, NEMA, IP rating: What makes a device rugged?

written by Garry Doran


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What is a ‘Rugged or Ruggedized Device’?

A rugged device is one that is capable of withstanding rough handling and operates reliably in harsh usage environments such as strong vibrations, extreme temperatures and wet or dusty conditions.

 


The terms rugged, drop tested, splash proof, water resistant or waterproof are basically just marketing terms. They don’t actually mean anything without context.


So how can you tell how ‘rugged’ or ‘waterproof’ a device really is?



IP Rating (International Protection Rating)

The IP rating, (aka international protection rating or ingress protection rating) is a two digit number (e.g. IP65) which classifies the protection provided by the case of a device against solids and liquids. The first number relates to solids, the second to liquids.


The rating ranges from 1-6 for solids and 1 to 8 for liquids. This rating is used to provide more accurate information about the protection level of a device rather than the usual marketing terms such as waterproof or water resistant.


The tables below give an explanation of the protection level each number represents:


Solids  (First digit of IP rating)  Level 	  Object size protected against 	  Effective against  0 	  Not protected 	  No protection against contact and ingress of objects.  1 	  >50 mm 	  Any large surface of the body such as the back of the hand, but no protection against deliberate contact with a body part.  2 	  >12.5mm 	  Fingers or similar objects  3 	  >2.5mm 	  Tools, thick wires etc.  4 	  >1mm 	  Most wires, screws etc.  5 	  Dust protected 	  Ingress of dust is not entirely prevented but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact.  6 	  Dust tight 	  No ingress of dust, complete protection against contact.   Example: IP6X means that the device is dust tight.   Liquids  (Second digit of IP Rating)  Level 	  Object size protected against 	  Effective against  0 	  Not protected 	   1 	  Dripping water 	  Dripping water (vertically falling drops) shall have no harmful effect.  2 	  Dripping water when tilted up to 15° 	  Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position.  3 	  Spraying water 	  Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.  4 	  Splashing water 	  Water splashing against the enclosure from any direction shall have no harmful effect.  5 	  Water jets 	  Water projected by a nozzle (6.3mm) against enclosure from any direction shall have no harmful effects.  6 	  Powerful water jets 	  Water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects.  7 	  Immersion up to 1m 	  Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1m of submersion).  8 	  Immersion beyond 1m 	  The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. Normally, this will mean that the equipment is hermetically sealed. However, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects.   Example: IPX4 means that the device is protected against splashing water.


The iPhone 7 and iPhone 7 Plus are the first Apple smartphones to come with IP ratings. They are rated IP67 meaning that they are completely dust tight and capable of surviving in up to 1 metre of water for 30 minutes or less.


The Samsung Galaxy S7 boasts an IP68 rating also meaning that it's completely dust proof but this model can survive in up to 5 feet of water for up to 30 minutes.



NEMA (National Electrical Manufacturer Association)

NEMA ratings are standards that are useful in defining the types of environments in which an electrical enclosure can be used. This rating system is defined by the National Electrical Manufacturer Association, and frequently signifies a fixed enclosure's ability to withstand certain environmental conditions.


Below is a table which shows the NEMA rating and definition with along with its equivalent IP rating:


 NEMA Rating 	  IP Equivalent 	  NEMA Definition  1 	  IP10 	  Enclosures constructed for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment and to provide a degree of protection against falling dirt.  2 	  IP11 	  Enclosures constructed for indoor used to provide a degree of protection to personnel against incidental contact with the enclosed equipment, to provide a degree of protection against falling dirt, and to provide a degree of protection against dripping and light splashing of liquids  3 	  IP54 	  Enclosures constructed for either indoor or outdoor used to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, snow, and windblown dust; and that will undamaged by external formation of ice on the enclosure  3R 	  IP54 	  Enclosures constructed for either indoor or outdoor used to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, and snow; and that will be undamaged by external formation of ice on the enclosure  3S 	  IP54 	  Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, snow, and windblown dust; and in which the external mechanism(s) remain operable when ice laden.  4 	  IP66 	  Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, snow, windblown dust, splashing water, and hose-directed water, and corrosion; and that will be  undamaged by the external formation of ice on the enclosure  4X 	  IP66 	  Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt, rain, sleet, snow, windblown dust, splashing water, hose-directed water, and corrosion; and that will be undamaged by the external formation of ice on the enclosure  5 	  IP52 	  Enclosures constructed for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against settling airborne dust, lint, fibers, and flyings; and to provide a degree of protection against dripping and light splashing of liquids.  6 	  IP67 	  Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against hose-directed water and the entry of water during occasional temporary submersion at a limited depth; and that will be undamaged by the external formation of ice on the enclosure.  6P 	  IP67 	  Enclosures constructed for either indoor or outdoor use to provide a degree of protection to the personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against hose-directed water and the entry of water during prolonged submersion at a limited depth; and that will be undamaged by the external formation of ice on the enclosure  12 and 12K 	  IP52 	  Enclosures constructed (without knockouts) for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against circulating dust, lint, fibers, and flying; and against dripping and light splashing of liquids  13 	  IP65 	  Enclosures constructed for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against circulating dust, lint, fibers, and flyings; and against the spraying, splashing, and seepage of water, oil, and non corrosive coolants.


The correlation between NEMA ratings and IP ratings are limited to dust and water. NEMA includes more stringent testing requirements to verify the protection from corrosive materials, external ice, oil immersions as well as dust and water. NEMA ratings are rarely applied to mobile devices as these stringent testing requirements are seldom needed.


Note that the comparison tablet above can only be used to convert NEMA ratings to IP ratings, but not vice versa.



MIL-STD (Military Standard) or MIL-SPEC (Military Spec)

The MIL_STD or MIL-SPEC is a series of guidelines established by the U.S. Department of Defense. It sets specific performance and manufacturing requirements for all types of equipment including Android devices.


MIL-STD-810G is the particular standard concerning rugged Android devices. It includes a large list of tests carried out in labs to simulate certain environmental variables including temperature extremes, low pressure (altitude), thermal shock, fungus(yes fungus…) and being frozen to name a few.



The problem with MIL-STD-810G compliance is that it can be misleading. There is no central body meaning companies can come up with their own versions of the tests to meet the standards.


It was explained by Dr. Conrad H Blickenstorfer like this:


“The MIL-STD-810G does not mandate standards or set minimum goals for the various tests; for the most part it simply describes how testing is to be conducted. This leaves considerable room for interpretation, and it is therefore important for manufacturers of rugged notebooks to provide detailed information on what tests were conducted, how exactly they were conducted, what the results were, and what those results actually mean. The claim that a product is "MIL-STD-810G tested" is not enough, and prospective customers should ask for more detail.”

Whether you are purchasing or selling a rugged device it is important to understand exactly what the terms and rating specifically mean. Just because a product is labeled as being waterproof doesn’t mean you can go deep sea diving with it or if it's labeled as being rugged it doesn’t mean it will survive being smashed by a hammer.


Next month I will take a look at some of the tests that are carried out on these devices in order for them to earn their ratings.


If you have any questions on this or any other topic we have covered please let me know in comment section below.


As usual -> Hope this helps and that you enjoy!
Garry @ Hatch

PS: If there is any topic you'd like me to cover just send me an email or a tweet.

 

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  • Sam

    Useful article — but does the IP rating tell you anything about build quality? For example I bought the “YI Action Camera,” a Go-Pro competitor, which has a waterproof case with an IP68 rating and advertises itself as capable of diving up to 40 meters. After one day of diving and snorkeling though, the plastic components are degrading and breaking apart. Guess I should have just gotten a GoPro instead.