MIL-STD-810, Method 507 Humidity Testing applies to items that are stored or deployed in warm, humid atmospheres. The purpose of Method 507 Humidity Testing is to determine a product’s resistance to warm, humid environments. It is intended to provide an indication of potential problems associated with humidity. MIL-STD-810 Humidity testing provides stressful conditions intended to reveal potential problem areas in material. It does not attempt to duplicate the complex temperature/humidity environment. The latest revision is Method 507.6 from MIL-STD-810H.
MIL-STD-810 Method 507 Humidity Testing consists of two procedures, Procedure I – Induced and Natural Cycles and Procedure II – Aggravated.
Adapting to Humid Environments: MIL-STD-810 Testing
Procedure I contains three natural cycles for test items that are open to the environment and three induced (storage and transit) cycles. The natural humidity cycles are Constant high humidity (Cycle B1), Cyclic high humidity (Cycle B2), and Hot-humid (Cycle B3). The induced (storage and transit) cycles are Induced constant high humidity (Cycle B1), Induced variable – high humidity (Cycle B2), and Induced hot-humid (Cycle B3).
Constant high humidity (Cycle B1) represents conditions in heavily forested tropical regions where nearly constant temperature and humidity prevails during rainy and wet seasons with little solar radiation exposure. Cyclic high humidity (Cycle B2) conditions occur in tropical areas where solar radiation is a factor. Hot-humid (Cycle B3) is unique to materiel that is deployed specifically in the Persian Gulf or Red Sea regions. It is not to be used as a substitute for worldwide exposure requirements where B1 or B2 would apply.
Induced constant high humidity (Cycle B1) is defined as a humid environment with relative humidity above 95 percent with nearly constant 27 °C (80 °F) temperature for periods of a day or more. Induced variable – high humidity (Cycle B2) conditions occur when material in the cyclic high humidity environment category receives heat from solar radiation with little or no cooling air. Induced hot-humid (Cycle B3) exists when items in the hot -humid category receive heat from solar radiation with little or no cooling air.
The test durations for Procedure I are listed in Table 507.6-II from MIL-STD-810H.
Procedure II – Aggravated contains more extreme temperature and humidity levels than those found in nature but requires shorter durations. The advantage of Procedure II is that it produces the effects of temperature-humidity faster than the natural or induced procedures identifying potential problems quicker. The aggravated 24 hour temperature-humidity cycle from MIL-STD-810H is shown in Figure 507.6-7. Although the combined 60 °C (140 °F) and 95 percent RH does not occur in nature, this combination of temperature and relative humidity has historically proven to reveal potential defects in most material. The minimum number of 24-hour aggravated cycles for the test is ten preceded by a 24 hour preconditioning step.
High Humidity Environment Failures
What are some failures that occur from High Temperature and High Humidity environments?
- Oxidation and/or galvanic corrosion of metals.
- Increased chemical reactions.
- Chemical or electrochemical breakdown of organic and inorganic surface coatings.
- Changes in friction coefficients, resulting in binding or sticking.
- Swelling of materials due to sorption effects.
- Loss of physical strength.
- Changes to electrical and thermal insulating characteristics.
- De-lamination of composite materials.
- Changes in elasticity or plasticity.
- Degradation of optical element image transmission quality.
- Degradation of lubricants.
- Condensation resulting in electrical short circuits.
- Fogging of optical surfaces.
The is a partial list of potential failures due to high temperature and high humidity environments. These issues underscore the critical need for rigorous and comprehensive humidity testing.
Why Choose DES for Your Humidity Testing?
Choosing the right testing lab for humidity testing can significantly impact the reliability and market readiness of your products. Delserro Engineering Solutions (DES) has a history of serving leading aerospace and military manufacturers as well as having state-of-the-art chambers to replicate the most demanding humid environments.
Why choose DES for your Humidity Testing?
- DES is an accredited MIL-STD 810 test lab.
- We have extensive experience and have performed numerous MIL-STD-810 humidity tests.
- DES has multiple chambers capable of performing MIL-STD-810, Method 507 Humidity Testing.
- DES has performed many MIL-STD-810 tests for leading aerospace and military product manufacturers.
If your product is required to function in the tropics or in high-humidity environments, contact DES to obtain a free quote and to schedule a MIL-STD-810 humidity test today.