Molecular Sieve Desiccant

General Information

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How Does It Work?
Molecular Sieves are synthetically produced Zeolites characterized by pores of uniform dimensions. Their unique structure allows the water of crystallization to be removed, leaving a porous crystalline structure. These pores, or "cages", want to re-absorb water or other molecules. Aided by strong ionic forces, the Molecular Sieve will absorb a considerable amount of water or other fluids. If the fluid to be absorbed is a polar compound, it can be absorbed with high loadings even at very low concentrations of the fluid. This strong absorptive force allows Molecular Sieves to remove many gas or liquid impurities to very low levels (PPM or less).

Temperature & Humidity Considerations:
Molecular Sieves retain their ability to absorb water molecules over a much wider spectrum of temperatures than other desiccant materials. Molecular Sieves also have a much higher equilibrium capacity for water vapor under very low humidity conditions. Molecular Sieves are very effective in reducing the water vapor content of gases in the parts per million range.

Regeneration:
Both Type 13X and 4A can be regenerated by evacuating or purging, usually at elevated temperatures. The purge gas temperature must be sufficiently high to bring the Molecular Sieve to a level of 400-600°F, but not exceed 1000°F. The degree of regeneration for Type 4A depends on the temperature and humidity of the purge gas and can strongly affect the product purity attainable. A thoroughly regenerated Molecular Sieve can produce water dew points below -150°F and CO2 levels less than 5 PPMV. The degree of regeneration for Type 13X depends on the temperature, pressure and humidity of the purge gas and affects the exit stream purity. It is possible to dry fluids to less than 0.1 PPM H2O and purity to less than 1 PPM total sulfur and CO2.

Why do I need desiccant?

Molecular Sieve Desiccant: Type 4A
Type 4A is the sodium form of Zeolite. Type 4A is typically used in regenerable drying systems to remove water vapor or contaminants which have a smaller critical diameter than 4 angstroms. With a smaller pore size, Type 4A is less subject to contamination; however, the moisture absorption rate will be less than that of Type 13X. Available in bead sizes 1/8" (4 x 8 mesh) or 1/16" (8 x 12 mesh).

Technical Data:

Nominal Pore Size: 4 angstroms
Type of Crystalline Structure: Cubic
Bulk Density: 46 lbs./cu. ft.
Equilibrium Water Capacity: 24% wt.
Water Content (as shipped): 1.5% wt. (max.)
Heat of Absorption (max.): 1,800 BTU/lb. H2O
Specific Heat (approx.): 0.23 BTU/lb./°F

Packaging: Sold in 30 lb. pails, 110 lb. drums and 300 lb. drums.

DESICCANT TYPE 4A
PART NO.	CONTAINER SIZE	BEAD SIZE	MESH SIZE
4A18-30	30 lb. Pail	1/8"	4 x 8
4A18-110	110 lb. Drum
4A18-300	300 lb. Drum
4A116-30	30 lb. Pail	1/16"	8 x 12
4A116-100	110 lb. Drum
4A116-300	300 lb. Drum

Molecular Sieve Desiccant: Type 13X
Type 13X is a modified form of the sodium Zeolite with a pore diameter of 10 angstroms. Type 13X is used commercially for general gas drying, air plant feed purification (simultaneous removal of H20 and CO2) and liquid hydrocarbon and natural gas sweetening (H2S and mercaptan removal). The larger pore size allows for faster absorption of moisture; however, it is more subject to contamination. Available in mesh sizes 4x8 and 8x12. Available in bead sizes 1/8" (4 x 8 mesh) or 1/16" (8 x 12 mesh)

Technical Data:

Nominal Pore Size: 10 angstroms
Type of Crystalline Structure: Body Centered Cubic
Bulk Density: 42 lbs./cu. ft.
Equilibrium Water Capacity: 29% wt.
Water Content (as shipped): 1.5% wt. (max.)
Heat of Absorption (max.): 1,800 BTU/lb. H2O
Specific Heat (approx.): 0.23 BTU/lb./°F

Packaging: Sold in 25 lb. pails, 110 lb. drums and 275 lb. drums.

DESICCANT TYPE 13X
PART NO.	CONTAINER SIZE	BEAD SIZE	MESH SIZE
13X18-25	25 lb. Pail	1/8"	4 x 8
13X18-110	110 lb. Drum
13X18-275	275 lb. Drum
13X116-25	25 lb. Pail	1/16"	8 x 12
13X116-110	110 lb. Drum
13X116-275	275 lb. Drum

If you are unsure which type and mesh size are required for your dryer, consult your dryer's manual.

PS&E Desert Dry desiccant is comparable with the following brands: Bry-Air, Carewell, Dehutech, Desiccare, Drierite, Drieaz, Dry Pak, Fluid Energy, Foremost, Grace, Graco, King, LPS, Multisorb, Pelco, Phonosorb, Sorbent Systems, Stulz, Van Air, Wittman.