Published: April 6, 2017
It’s difficult to consider salt, sand, dust, and fog as an enemy on the battlefield that can destroy your resources, but it happens more often than you think. These small particles can easily get inside computers, servers, and displays, ruining the inner workings of these devices and corroding the rugged shell around it. Because of this, all electrical devices that may encounter these environments must go under stringent testing to ensure that these particles do not clog openings/filters, cause cracking of the protective coating, or cause any electrical failures.
In order to combat these pesky fragments of nature, the military introduced a standard of “environmental engineering considerations and laboratory tests” labeled MIL-STD-810. MIL-STD-810 tests the extremes that a system will experience throughout its service life. Test methods 509.5 and 510.5 covers salt, fog, blowing sand, and dust. These tests are approved for use by all departments within the United States Department of Defense (DoD) and are also used for commercial and industrial units.
Testing for Salt and Fog
Fog and salt are tested under method 509.5 and focuses on accelerated corrosion and electrical problems. Salt and fog testing are most common for Naval use or any sections of the military that find themselves in coastal areas where salt spray and fog is unavoidable. The main objective of these tests is to see how protective the coating on a server, LCD or mission computer is under intense salt and fog conditions. If the outer shell is compromised, the inner electrical workings are then put under stress and will be evaluated as to whether or not there are failures.
The machines used for the testing are required to produce an environment with 5% salt/fog and is circulated with the system inside. Testing usually lasts two full days with a two-day drying period to follow. Cycling by testing and drying for 24 hours at a time has also proven to be effective as the changes tend to put more stress on the system and simulate more of a real environment. Following the tests, the unit is inspected by experts for corrosion effects, physical deformities, and any electrical problems.
A look into environmental testing at Core Systems Labs
Testing for Sand and Dust
Sand and dust are tested under method 510.5 and looks for any abrasions, penetration, clogging, temperature changes, etc. Blowing sand and dust testing is most common for sections of the military that are land-based, especially in deserts and remote areas. Under method 510.5, dust is defined as anything less than 150um and sand is defined as anything in the range of 150um-850um. During the testing process, the machines look to expose the system to any vent clogging, scratches, electrical problems and more.
Temperatures need to be kept at the systems highest operating temperature throughout the testing period to fully understand how they would operate in a desert-type region. The machines used for testing are built to mimic desert winds as much as possible by keeping the humidity below 30% and the air velocity at 300-1750 ft. Surprisingly there are different types of sand and dust to test based on regions in which the unit will be used. Testing takes approximately 12 hours and cycles through different temperature extremes. During these cycles, systems are rotated every 90 minutes to expose all sides to blowing sand and dust.
Whether a system will be used on land or at sea, testing for salt, fog, sand, and dust is imperative to creating a truly rugged server, portable computer, or LCD display. A small speck of sand can infiltrate a system and compromise a mission, so testing methods 509.5 and 510.5 of MIL-STD-810 should not be overlooked.