ENCLOSURES

An enclosure is a mechanical item which either partly or wholly surrounds a component or assembly. Enclosure tests determine the suitability of equipment enclosures and sealing design techniques to provide various functions, including the following:

Physical and environmental protection to the enclosed items.
Protection from items within the enclosure to personnel or objects outside the enclosure.
Means for ventilating items within the enclosure.
Means for cooling items within the enclosure.
Sealing equipment to protect against leakage, both internal and external.
Enclosures are designed to provide various degree of protection. A partial listing of the degrees of protection specified in MIL-STD-108 is provided below:

AIRTIGHT - DRIPPROOF

DUSTTIGHT - DUSTPROOF

SPLASHPROOF - SPRAYTIGHT

SUBMERSIBLE - WATERTIGHT

EXPLOSIONPROOF - HERMETIC

The following sections provide further information on some of the enclosure tests. For information on additional enclosure testing, contact the laboratory.

WATER

The water test determines the effectiveness of protective covers, cases, and seals in items exposed to rain, water spray, or dripping water during storage, transit, or operation, in preventing the penetration of water into the material, as well as the capability of the material to satisfy its performance requirements during the after exposure to rain. The rain testing also determines any physical deterioration of the material caused by the rain, the effectiveness of any water removal system, and the effectiveness of protection offered to a packaged material.

Water testing is specified in the following:

MIL-STD-108, MIL-STD-810, MIL-I-983, MIL-E-5272, MIL-F-7872, MIL-C-8811, MIL-G-10228, MIL-R-11050, MIL-R-12574, MIL-R-13312, MIL-F-13926, RTCA/DO-160, UL-427, UL-471, UL-606, UL-50, TA-NWT-000487, GR-487-CORE, NEMA 250-1991, NEMA 250-1997

IMMERSION

The test is performed to determine the effectiveness of the seals of component parts under immersion conditions. The immersion of the part under evaluation into a liquid, at widely different temperatures, subjects it to thermal and mechanical stresses which will readily detect a defective seal assembly, or a partially closed seam or molded enclosure. Defects of these types can result from faulty construction or from mechanical damage such as might be produced during physical or environmental tests.

Immersion testing is specified in the following:

MIL-PRF-27, MIL-T-27, MIL-STD-108, MIL-STD-202, MIL-STD-750, MIL-STD-810, MIL-STD-3885, MIL-S-3928, MIL-E-5272, MIL-T-7928, MIL-G-10228, MIL-M-10399, MIL-C-11015, MIL-R-11050, MIL-R-11539, MIL-F-13926, MIL-C-15305, MIL-T-15514, MIL-F-15733, MIL-P-16232, MIL-E-16400, MIL-F-18327, MIL-H-18766, MIL-R-19648, MIL-C-24166, MIL-L-24223, MIL-C-24308, SAE-J1942, US COAST GUARD NO. 493, ASTM E-644-91, NEMA 250-1991, NEMA 250-1997, UL-50, DOD-F-16232

SEAL

This test determines the effectiveness of the seals of component parts which have internal cavities which are either evacuated or contains air or gas. A defect in any portion of the surface area of a sealed part can permit entrance of damaging contaminants which will reduce its effective life. This test detects leaks due to the use of inferior sealing materials, or to the manufacturing processes used to form the seal.

Seal testing is specified in the following:

MIL-PRF-27, MIL-T-27, MIL-STD-202, MIL-STD-750, MIL-S-3928, MIL-B-7949, MIL-S-8484, MIL-A-8625, MIL-S-8805, MIL-A-8897, MIL-C-11015, MIL-C-12889, MIL-C-15240, MIL-F-15733, MIL-E-16400, MIL-P-17840, MIL-T-17275, MIL-P-17869, MIL-F-18327, MIL-R-19648, MIL-C-22317, MIL-R-24414, MIL-T-28800, ASTM F1511-98, ASTM B16.104-1976, UL-50, UL-213, UL-886, UL-1203