Mil-D 3464E is a U.S. military specification for clay and silica gel bags. One “Unit” is the amount needed to adsorb 3 grams of water at 25˚C and 20% RH, and also 6 grams at 40% RH. The approximate weight of a unit is one ounce, when dry.
Type I – the basic requirements for absorption, reactivation, dusting, and durability.
Type II – same requirements as Type I, but with a fabric that’s low dust (usually Tyvek).
Type III – same requirements of Type I, but with a fabric that’s resistance to hot water.
Specification for dust is less than 5.0 mg/unit for Type I and III, and less than 0.5 mg/unit for Type II.
Mil Spec. bags can be reactivated in an oven. On each bags is printed the temperature and time needed. After reactivation, the bags must have 90% of their original adsorption capacity and be able to pass a drop test, to show that the sealing is still intact.
This information shall be printed on each bag:
- Desiccant, Activated, Bagged For Package Use and Static Dehumidification
- Type I, II, or III
- Manufacturer’s designation
- Number of Unit’s
- Reactivation temperature in bag ____ºF
- Reactivation time ____ hours
- Manufacturer’s name and address