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Immersion

MIL-STD Immersion Testing

The immersion test helps determine if material can withstand immersion in water and operate as required during or following immersion. Method 512.7 of MIL-810 immersion is used for material that may be exposed to water ingress during its life cycle.

This test may be used to verify watertightness instead of a rain test. That is if the material configuration is the same, and the method of water ingress is well understood. Immersion tests are not meant for buoyant items, unless  specific applications could hold the material under water.

Keystone Compliance is an ingress protection lab with significant MIL-810H immersion and MIL-810G immersion experience. Our test engineers have an in-depth knowledge of the requirements of water enclosure testing. Below is a summary of Method 512.7, as derived from the MIL-STD 810H immersion testing section. It also includes information from the MIL-STD 810G immersion section.

What are the Effects of Leakage During Immersion Ingress?

Penetration of water into materiel or packaging enclosures can result in problems. Water enclosure ingress could lead to fouling of lubricants between moving parts. Electrically conductive paths could form that may cause equipment to malfunction or become unsafe to operate.

Direct exposure to water will also lead to corrosion or the high humidity levels. For materials operated by fuel water immersion may impair the burning qualities of explosives, propellants, fuels, etc. Other failures of vehicle engines may be revealed during ingress protection testing.

What is the Procedure for IP Code Testing?

There are at least two philosophies related to this test sequence. One approach is to conserve test item life by applying what are perceived to be the least damaging environments first. For this approach, generally apply the immersion test prior to most other climatic tests.

Another approach is to apply environments to maximize the likelihood of disclosing sequential problems. For this approach, consider the immersion test before and after structural tests. This will help determine the material’s resistance to dynamic tests.

Procedure I is called Immersion and Procedure II is called Fording. While both procedures involve some degree of immersion, they differ in that Procedure I primarily addresses leakage during immersion. Procedure II focuses on vehicles traversing a body of water or materiel secured to such vehicles. When selecting procedures, consider:

  • The functional purpose of the material. From the requirements documents, determine the functions to be performed by the material when partially or completely immersed in water.
  • The natural exposure circumstances.
  • The test data required to determine whether the functional purpose of the material has been met.

How Are Appropriate Test Levels and Conditions Determined?

Special parameters and test conditions are determined from requirements documents, Life Cycle Environmental Profile (LCEP), and other  information provided. From these sources of information, determine the functions to be performed by the material while immersed or following exposure to immersion. Then, determine the depth and duration of immersion expected in areas in which the material is designed to be employed.

How Should Temperature Be Conditioned for Best Immersion Testing?

Experience has shown that a temperature differential between the test item and the water can affect the outcome of the test. The temperature of the water should be 18 °C plus or minus 10 °C. Increasing the test item temperature above the water temperature includes heating the test item to establish a pressure differential while cooling. This helps determine if the seals or gaskets leak under relatively low pressure differential, and induce expansion/contraction of materials.

Although desired, establishing a specific temperature differential for Procedure II tests is often impractical due to the size of the material. Also, consider material adjacent to heat-producing equipment such as engines, and use temperatures indicative of actual exposure. The duration of conditioning prior to immersion should be two hours to ensure maximum heat loss during immersion and cooling.

Unless otherwise identified, three options are provided for the conditioning of the test item:

  • 27 °C above the water temperature – to represent exposure to solar heating immediately prior to immersion.
  • 10 °C above the water temperature – to represent a typical temperature difference between materiel and water.
  • Equal to the water temperature – to represent situations in which little or no temperature differential exists. This may be used for large items when adequate conditioning facilities are not available. However, the depth of immersion must be adjusted to result in the same differential pressure.

How Deep Should The Test Item Be Immersed?

For complete immersion use a 1m covering depth or the required depth identified in the LCEP or other documents. This is measured from the uppermost surface of the test item to the surface of the water. When testing to depths greater than 1m within a pressure vessel, completely immerse the test item in water, then apply pressure. For partial immersion specify depths as being measured from the base of the material rather than from the top.

How Long Should the Immersion or Exposure of the Test Item Last?

Duration of immersion in the enclosure testing lab should be typical of that expected during use. If this duration is unknown, a 30-minute immersion period is considered adequate. One hour fording durations are best, but may be extended if justified by the expected life cycle profile.

What Information is Required Prior to IP Code Certification Testing?

To conduct immersion or fording tests adequately certain pieces of information are required. Water temperature, and the temperature to which to heat the test item must be known, along with duration. The fording and immersion depths and durations are needed. Tiedown precautions should also be taken to prevent unrealistic stress.

What Information Is Gathered During and After the Test?

The formation and location of bubbles during testing will indicate leaks. It is also important to know the water temperature 15 minutes following immersion and the pretest water and test item temperatures.

After completion of the test the amount of free water inside the item ,and probable points of entry should be noted. Notes should be made about the actual covering depth of water and the duration of immersion. Any deviations from the original test plan and appropriate photographs should be recorded.

Who Should You Trust for Immersion Certifications for Your Product?

Keystone Compliance has been recognized as one of the best immersion labs. We employ experienced test engineers who understand the requirements of MIL-810 immersion compliance standards. Our immersion testing lab is fully equipped with the appropriate devices. This is to ensure the best dew point testing for all our customers products.

Are you looking for an immersion laboratory to perform compliance testing for your product?  Keystone Compliance is equipped to provide a variety of testing for commercial, military, and aerospace products. Contact us to learn why so many manufacturers rely on Keystone Compliance to meet their compliance testing needs.

There have been several versions of immersion testing procedures in MIL-STD-810 immersion testing. Below is a list of each version and the appropriate method number: