What is MIL-D-3464 desiccant?
MIL-D-3464E is a military specification that describes the requirements and standards for packaged, activated desiccant used to remove moisture from air and gases in enclosed spaces. The most common desiccants used are silica gel, bentonite clay, molecular sieve, or activated alumina. The standard is also used by the Norwegian Armed Forces and the Norwegian defense industry.
The specification was last updated in 1987 and is approved for use by all departments of the United States Department of Defense. Its purpose is to prevent corrosion, mold, and damage to equipment stored in closed containers or packaging.
Why is MIL-D-3464E important?
MIL-D-3464E ensures that desiccants used in military and industrial applications meet strict requirements for moisture control, durability, and safety. This is crucial for protecting valuable equipment from moisture damage during storage and transport. The unit of weight commonly used is units.
A "unit" refers to the quantity of desiccant needed to meet the adsorption capacity established in the MIL-D-3464 standard: "A desiccant unit is that quantity of desiccant, as received, which will adsorb at equilibrium with air at 25 degrees Celsius at least the following quantities of water vapor:
(a) 3.00 grams at 20 percent relative humidity (R.H.), and
(b) 6.00 grams at 40 percent R.H.”
Generally, the following applies:
25 grams of silica gel = 1 unit.
Example:
A bag marked 16 units contains 400 grams of silica gel (16 x 25 g).
A bag with 500 grams of silica gel corresponds to 20 units (500 g / 25 g).
The specification is also useful for civilian applications where preservation and corrosion protection are critical, for example in electronics, medical equipment, and sensitive items.
Summary of MIL-D-3464E
What does the specification cover?
- The specification covers packaged, chemically inert desiccant that adsorbs moisture from air and gases.
- The desiccant is intended for static dehumidification of packages, containers, and closed spaces to protect against corrosion and mold.
Classification of desiccants The desiccant is supplied in three main types, where the difference lies in the bag material:
- Type I: General purpose, for standard applications.
- Type II: Dust-free bags, for critical applications where dust cannot be tolerated.
- Type III: For special conditions (only in 8- and 16-unit bags).
Performance requirements
- Adsorption capacity: A desiccant unit must be able to adsorb at least 3 grams of water at 20% relative humidity and 6 grams at 40% relative humidity at 25°C.
- Volume: One unit of desiccant must not exceed a volume of 45 milliliters.
- Moisture control: One unit of desiccant must be able to keep the relative humidity below 60% in a sealed metal box.
- Dust: Type I and III have strict requirements regarding dust quantity, while Type II must not produce more than 0.5 milligrams of dust per bag.
- Corrosion: The desiccant must not cause corrosion on metals such as steel, brass, magnesium, and aluminum.
- Durability: The bags must withstand dropping, vibration, and reactivation without tearing or leaking.
Packaging and labeling
- The bags must be labeled with type, number of units, reactivation temperature, reactivation time, manufacturer, and specification number.
- The desiccant is packed in 20-liter pails, depending on size and need.
- Each container must contain a humidity indicator to show the moisture level.
Reactivation
- The desiccant can be reactivated by heating to at least 120°C for up to 24 hours.
- After reactivation, the desiccant must retain at least 90% of its original adsorption capacity and 80% of its original adsorption rate.
We can supply MIL-D-3464 desiccant in the following bag sizes:
- ½ unit (95 x 50 mm)
- 1 unit (115 x 50 mm)
- 2 unit (130 x 80 mm)
- 4 unit (170 x 80 mm)
- 8 unit (175 x 125 mm)
- 250 grams (185 x 125 mm)
- 16 unit (255 x 125 mm)
- 500 grams (270 x 125 mm)
- 1 kg (320 x 160 mm)
- These bags are produced either in Type I and II (dust-free version) or Type I (general-purpose version).
