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MIL-STD 108 Testing of Enclosures for Electronic Equipment

The Military Standard (MIL-STD) 108 test method evaluates an enclosure’s susceptibility to the ingress of fluids and solid foreign objects. As an ISO-17025 accredited environmental compliance test lab, we realize the importance of ingress protection and enclosure testing of electrical and electronic equipment. Meeting the MIL 108 compliance requirements can be difficult. We understand the challenges and guide companies through the process.

Keystone Compliance creates an accurate test plan to eliminate expensive over-testing. Our accurate test reports are delivered quickly. Furthermore, we expedite comprehensive reports shortly after the completion of the test. Lastly, what separates us from NRTLs is our consultative approach throughout the entire test program.

Request a quote to learn why we are one of the fastest-growing compliance test labs in the country. Ready to get started? We are. Contact us to see why so many companies work with Keystone each year to achieve their environmental standard test needs.

Summary of MIL-108 Compliance Testing of Enclosures

This military standard, method 108, evaluates the protection an enclosure provides for electrical and electronic equipment.

An enclosure is a mechanical item that surrounds some electrical item or group of items. The functions of an enclosure include the following:

  • Provide physical protection to the enclosed items
  • Provide means for ventilation items within the enclosure
  • Provide a means for cooling items within the enclosure
  • Provide external facilities for mounting on, or securing to, a structure. This includes a wall or bulkhead
  • Provide interior support for subassemblies, parts, or similar items
  • Provide a reduction of radiated audible noise or radio interference

MIL-STD 108 Testing Program

Test Procedures

The following procedures apply to specific degrees of an enclosure’s protection. If an enclosure is unable to meet the specified requirements, it is considered to have failed the MIL 108 test.


The total time of each test is 24 hours minimum. The equipment is operating as ON for 8 hours, OFF for 4 hours, ON for 8 hours, and OFF for 4 hours. A change in a pressure difference of more than 0.6 p.s.i.g will result in a rejection of the test.


A drip test is used to determine the ability of the enclosure equipment to operate when subjected to dripping fluids. For this test, the enclosure is placed below a dripping device. The minimum amount of water is 1000 cubic inches per square foot in 60 minutes. During this test, the enclosure is oriented in 5 different positions at 15 or 45 degrees of tilt.


Dustproof testing is conducted in accordance with Method 510 of MIL-STD-810. However, the ambient temperature of 145 C is occasionally omitted. The equipment must be operated during the entirety of the test.


Similar to dustproof testing, this test is conducted in accordance with the MIL-810 standard. The entry of any dust after the disassembly and examination with result in a failure of the test.


Splash-proof testing is conducted with the enclosed equipment placed or mounted in a typical operating position. For this test, the water stream is sprayed on both the equipment and the supporting surface. The equipment must be operating during the test.


Immersion testing must be conducted for 24 hours at 15, 50, or 1600 feet. The equipment must be operating during the first and last third of the test. An internal vacuum, external pressure, or a combination thereof can be employed to conduct these tests. This will assist in creating a pressure differential equivalent to the submergence depth or pressure differential.

Test Report

After the completion of the test, a report is compiled of the following information:

  • Test procedures
  • Critical components
  • Test duration
  • Test levels
  • Initial failure and results
  • Any deviations from the planned test program

Expert Military Standard 108 Enclosure Testing

Keystone has a full lab of test equipment which permits us to provide short lead times on scheduling. Our team strives to give our customers more time and energy on product development instead of testing. In addition to MIL-STD 108 testing, Keystone has a full scope of expertise including fungus, solar radiation, and vibration.

Have a question about our ingress protection testing capabilities? Contact us to discuss the best course of action.