To be considered rugged, computers have to undergo multiple tests for ruggedness. The industry standards are MIL-STD test methods and the Ingress Protection scale.
- MIL-STD tests, i.e. the United States military standard for equipment, include twenty-four laboratory test methods that ensure equipment can handle low pressure at high altitudes; exposure to high and low temperatures, plus temperature shocks; rain; humidity; sand and dust exposure; leakage; and shock and vibration.
- The Ingress Protection scale measures devices for protection against dust and liquids. The ratings are displayed as a two-digit number. The first digit reflects the level of protection against dust, and the second digit reflects the level of protection against liquids (water). An IP65 rating would ensure complete protection against dust and protection against water jets.
These testing standards measure a computer’s ability to withstand the toughest environments in the world. Here’s how the most important tests are carried out for individual environmental factors:
Drop and shock testing. Eight different drop test procedures cause shock or impact in different ways. The “transit drop test” is the most cited. It requires items to survive a total of 26 drops from a height of 122 cm, on each face, edge and corner, onto a hard surface such as concrete.
Liquid-resistance testing. During water-resistance tests, a computer is exposed to powerful water jets from many directions. The test duration, water volume and water pressure vary depending on the rating.
Vibration testing. Vibration tests use laboratory shakers to simulate being on a vehicle or being carried by a person, with variations in the vibrations’ wave form, frequency and intensity depending on the type of device and the environment being simulated.
Sand and dust testing. Dust-resistance procedures test ingress of small dust particles. Flour and sand are projected onto the device at variable high wind speeds and high temperatures for several hours as the device is rotated.
Extreme temperature testing. Testing for operability in high and low temperatures includes exposing the device to extreme heat or cold while it is turned off (storage), while it is being turned on and used (operation), and while it is being used in normal operational temperatures after having been exposed to higher storage temperatures (tactical-standby to operational).
Humidity testing. During humidity testing, computers are exposed to tropical heat with humidity well over 90 percent for several days. Many of the same features that make mobile computers liquid-resistant also help prevent damage from high humidity.