Molecular Sieve type 3A is an alkali metal alumino-silicate; it is the potassium form of the type A crystal structure. Type 3A has an effective pore opening of about 3 angstroms (0.3nm). This is large enough to allow in moisture, but excludes molecules such as unsaturated hydrocarbons which can potentially form polymers; and this maximizes lifetime when dehydrating such molecules.

Typical Chemical Formula
0.4K2O 0.6Na2O Al2O3 2.OSiO2 4.5H2O
SiO2 : Al2O3 ≈2 

Technical Parameter
 
Typical Application 
Drying of unsaturated hydrocarbons (e.g. ethylene, propylene, butadien) Cracked Gas Drying
Drying of natural gas, if COS minimization is essential, or a minimum coadsorption of hydrocarbons is required.
Drying of highly polar compounds, such as methanol and ethanol
Drying of liquid alcohol Static, (non-regenerative) dehydration of insulating glass units, whether air filled or gas-filled.
Drying of refrigerants

Regeneration
Molecular sieve Type 3A can be regenerated by either heating in the case of thermal swing processes; or by lowering the pressure in the case of pressure swing processes.
To remove moisture from a 3A molecular sieve, a temperature of 200-230°C is required. A properly regenerated molecular sieve can give moisture dew points below -100°C.
The outlet concentrations on a pressure swing process will depend on the gas present, and on the conditions of the process.

Size 
3A - Zeolites are available in beads of 1-2 mm, (10x18 mesh) 2-3 mm, (8x12 mesh) , 2.5-5 mm, (4x8 mesh) and as powder, and in pellet 1.6", 3.2".

Attention
To avoid damp and pre-adsorption of organic before running, or must to be reactivated.