2.1 Selecting the Sand and Dust Method
After examining requirements documents and applying the tailoring process in Part One of this Standard to determine where sand and dust environments are foreseen in the life cycle of the materiel, use the following to confirm the need for this Method and to place it in sequence with other methods.
2.1.1 Effects of Sand and Dust Environments
The blowing sand and dust environment is usually associated with hot-dry regions. It exists seasonally in most other regions. Naturally-occurring sand and dust storms are an important factor in the deployment of materiel, but the induced environment created by the operational (battlefield, training, etc.) environment can be more severe. Consider the following typical problems to help determine if this Method is appropriate for the materiel being tested. This list is not intended to be all-inclusive.
a. Abrasion and erosion of surfaces.
b. Penetration of seals.
c. Degraded performance of electrical circuits.
d. Obstruction/clogging of openings and filters.
e. Physical interference with mating parts.
f. Fouling/interference of moving parts.
g. Reduction of heat transfer.
h. Interference with optical characteristics.
i. Overheating and fire hazard due to restricted ventilation or cooling.
j. Wear (increased fretting due to imbedding between mating surfaces).
- k. Increased chaffing between non-mating contacting surfaces.
- Weight gain, static/dynamic balance.
m. Attenuation of signal transmission.
2.1.2 Sequence Among Other Methods
- a. General. Use the anticipated life cycle sequence of events as a general sequence guide (see Part One, paragraph 5.5).
- b. Unique to this Method. This Method will produce a dust coating on, or severe abrasion of, a test item that could influence the results of other MIL-STD-810 methods such as Solar Radiation (Method 505.7), Humidity (Method 507.6), Fungus (Method 508.8), and Salt Fog (Method 509.6). Therefore, use judgment in determining where in the sequence of tests to apply this Method. Additionally, results obtained from the Solar Radiation Test (Method 505.7) may be required to define temperature parameters used both in this Method and in High Temperature (Method 501.7). On the other hand, the presence of dust in combination with other environmental parameters can induce corrosion or mold growth. A warm humid environment can cause corrosion in the presence of chemically aggressive dust.
2.2 Selecting Procedures
This Method includes two test procedures, Procedure I - Blowing Dust, and Procedure II - Blowing Sand. Determine the procedure(s) to be used. If settling dust is of concern, concentration levels can be obtained from International Electrotechnical Commission (IEC) 60721-2-5, and test procedures for settling dust can be obtained from IEC 60068-2-68 Test Lb. For outdoor testing, guidance is provided in Test Operations Procedure (TOP) 01-2-621 Outdoor Sand and Dust Testing.
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2.2.1 Procedure Selection Considerations
When selecting procedures, consider:
- a. The operational purpose of the materiel. From the requirements documents, determine the functions to be performed by the materiel in a sand or dust environment and any limiting conditions such as storage.
- b. The natural exposure circumstances.
- c. The test data required to determine if the operational purpose of the materiel has been met.
MIL-STD-810H
METHOD 510.7
- d. Procedure sequence. If both sand and dust procedures are to be applied to the same test item, it is generally more appropriate to conduct the less damaging first, i.e., blowing dust and then blowing sand.
2.2.2 Difference Among Procedures
While both procedures involve sand and/or dust, they differ on the basis of particle size and type of movement. These test procedures are tailorable to the extent that the user must specify the test temperature, sand and/or dust composition, test duration, and air velocity.
- a. Procedure I - Blowing Dust. Use Procedure I to investigate the susceptibility of materiel to concentrations of blowing dust (< 150 µm).
- b. Procedure II - Blowing Sand. Use Procedure II to investigate the susceptibility of materiel to the effects of blowing sand (150 µm to 850 µm).
2.3 Determine Test Levels and Conditions
Having selected this Method and relevant procedures (based on the materiel's requirements documents and the tailoring process), it is necessary to complete the tailoring process by selecting specific parameter levels and special test conditions/techniques for these procedures based on requirements documents, Life Cycle Environmental Profile (LCEP), and information provided with this Method. From these sources of information, determine the functions to be performed by the materiel in sand and dust environments, or following storage in such environments. Then determine the sand and dust levels of the geographical areas and micro-environments in which the materiel is designed to be employed. To do this, consider the following in light of the operational purpose and life cycle of the materiel.
2.3.1 Identify Climatic Conditions
Identify the appropriate climatic conditions for the geographic areas in which the materiel will be operated and stored, and whether or not test item needs to be operated during the test.
2.3.2 Determine Exposure Conditions
Base the specific test conditions on field data if available. In the absence of field data, determine the test conditions from the applicable requirements documents. If this information is not available, use the configuration guidance in paragraph 2.3.3, as well as guidance provided in paragraphs 4.1.1 and 4.2.1 for procedures I and II, respectively.
2.3.3 Test Item Configuration
Use a test item configuration that reproduces, as close as possible, the anticipated materiel configuration during storage or use, such as:
- a. Enclosed in a shipping/storage container or transit case.
- b. Protected or unprotected.
- c. Deployed realistically or with restraints, such as with openings that are normally covered.