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AECTP 300 Method 307 Immersion Compliance Testing

AECTP Method 307 immersion testing determines if a material can withstand immersion or partial immersion. Meeting the AECTP 300 climatic testing requirements can be challenging. Not only do we understand the challenges, but we help guide companies through the process. 

From concept through compliance, Keystone meets all of our customer’s needs under one roof. We tailor each test plan to individual customer requirements minimizing unnecessary costs and over-testing. Our expert test engineers work with clients to quickly develop appropriate and concise test plans.

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

Summary of AECTP 300 Environmental Climatic Compliance Testing

The AECTP 300 standard is intended to be used in conjunction with four other AECTP test standards (AECTP 100, 200, 400, and 500). Furthermore, the AECTP standard provides advice for preparing environmental test specifications, plans, and procedures.

AECTP 300 evaluates climatic environments that occur individually or in combination with other climatic or mechanical environments.

The AECTP 300 tests outlined provide exposure to simulated conditions from which a degree of confidence can be established. 

During testing, the configuration used for the selected test should be the configuration used within the unit’s life cycle. As a minimum, the following is considered: 

  • In the shipping/storage container or transit case.
  • Protected or unprotected.
  • In its normal operating and thermal configuration.
  • Modified with kits for special applications.

Any of the following will be classified as a failure:

  • A deviation of monitored functional parameter levels beyond acceptable limits.
  • Nonfulfillment of safety requirements or the development of safety hazards.
  • Nonfulfillment of specific test item requirements.
  • Changes to the test item that could prevent it from meeting its intended service life or maintenance requirements.

Scope of AECTP 307 Immersion Compliance Testing

AECTP Immersion Method 307 testing determines if a material can withstand immersion or partial immersion. More specifically, the unit must operate as required during or following immersion.

The AECTP 307 immersion test is usually more severe than the rain test (AECTP Method 310). In some cases, this test is used to verify water tightness in lieu of a rain test. However, this is provided that the material configuration is the same for both situations.

Generally, both rain and immersion tests are performed. When subjecting a unit to AECTP 310, the impact of rain causes the pumping of water across seals. This does not occur in the immersion test, as seals are held tight against the backing plate by static pressure.

The penetration of water into material or packaging can result in the following problems:

  • Fouling of lubricants between moving parts
  • Formation of electrically conductive paths that may cause electronic equipment to malfunction or become unsafe to operate
  • Corrosion due to direct exposure to the water or to the relatively high humidity levels caused by water
  • Impairment of the burning qualities of explosives, propellants, fuels, etc
  • Failure of vehicle engines to operate

AECTP 307 Immersion Compliance Test Procedures


In most cases, the immersion test includes heating the test item. This establishes a pressure contrast. In turn, it will determine whether the seals or gaskets leak under a relatively low-pressure differential. Three options are given for the conditioning of the test item.

  1. 27C above the water temperature. This represents the exposure to solar heating immediately prior to immersion.
  2. 10C above the water temperature. This represents a typical temperature difference between the material and water.
  3. Equal to the water temperature. This represents situations where little or no temperature differential exists.

It is recommended that the duration of conditioning before testing is at least two hours after the temperature stabilization of the test item.


There are two procedures that can be performed for this AECTP 307 test.

Immersion: For this test, a 1m representative covering depth is chosen or an equivalent pressure is applied. The duration of immersion should represent the anticipated time during use. If this duration is unknown, a 30-minute immersion period is carried out.

Fording: The test depth ranges from 0.5m to 1.5m. The fording test can be conducted in one of two ways. First, by towing or driving the test item through the water. Second, by securing the test item in a tank and flooding the tank to the required depth.

For fording test durations, a minimum of one hour is used.


Following the AECTP immersion test, a report is created. In addition to general information, any evidence of water penetration into the test item is assessed for its short and long term effects.

Expert AECTP 307 Immersion Compliance Test Lab

Our team strives to give our customers more time and energy on product development instead of testing. Keystone has a full lab of test equipment which permits us to provide short lead times on scheduling.

Request a quote to find out for yourself about the Keystone difference. Have a question about our immersion testing capabilities? Contact us or call (724) 657-9940 and we will determine the best course of action.

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