Molecular Sieve Beads 3A, Ethanol Dehydration
ABOUT THIS PART
3A molecular sieve beads for drying ethanol. $54.95 per 10 lb in 4x8 mesh, $49.95 per 10 lb in 8x12 mesh, or take the rest of a lot at $349.95 for 80 lb of 4x8 and $199.95 for 50 lb of 8x12. Sealed in bags, moisture carded, dry stored in Bend, Oregon.
3A for ethanol, 4A for hydrocarbons
- This is a hard rule, not a preference. A pore of 4 angstroms or more adsorbs the ethanol molecule itself, so 4A on an ethanol system wastes your beads and your solvent at the same time.
- Drying butane or propane instead? Buy the 4A beads.
- 5A suits neither. A 5 angstrom pore adsorbs n-butane and propane themselves.
Sizes and price
| Mesh | Pack | Price | Per lb |
|---|---|---|---|
| 4x8, the larger bead | 10 lb | $54.95 | $5.50 |
| 4x8, the larger bead | 80 lb, the rest of the lot | $349.95 | $4.37 |
| 8x12, the smaller bead | 10 lb | $49.95 | $5.00 |
| 8x12, the smaller bead | 50 lb, the rest of the lot | $199.95 | $4.00 |
Same 3A chemistry either way. The larger bead gives lower pressure drop across the bed, the smaller bead gives more surface area per pound.
Two ways to buy on purpose. Take a 10 lb pail to top up, or take the whole lot and the bucket is gone in one order at a price no distributor will match. There is one lot of each mesh and when it is gone it is gone.
This is clearance stock and it is not being restocked. It has been sealed in bags, some with moisture indicator cards, and stored in one of the driest climates in the country, so there is no regeneration caveat and nothing is sold as is.
How much you need
- Roughly 100 to 190 lb of 3A per 100 gallons of ethanol, depending on how wet the ethanol is.
- Worked example: 100 gallons of 191 proof carries about 4.5 gallons of water, near 37.5 lb, against a bead capacity of up to about 40 percent of bead weight. Efficiency falls off past about 20 percent.
- Run a 10 micron sintered disc on both sides of the bed. Beads shed dust, and dust downstream of the dryer ends up in your product.
- A 6 x 24 filter sock is the tidy way to change beads, because it keeps them contained instead of loose in the housing.
Regeneration
- Heat to 250 F (121 C), under vacuum or purging with a carrier gas. That is the figure the bead supplier publishes.
- Do not overshoot it. Excessive temperature decomposes the beads, and a decomposed bead does not come back.
- The step by step procedure is in 3A Sieve Bead Regeneration, and the background on pore sizes is in Molecular Sieves.
SPECIFICATIONS
▦ IN YOUR MANUAL
This part appears in the operator manual that ships with your system. The QR code there links to this page.
◈ REFERENCE FOR THIS PART
COMMON QUESTIONS
3A or 4A?
3A for ethanol, 4A for hydrocarbons. This is not a preference, it is a hard rule. Pores of 4 angstroms and larger adsorb ethanol itself, so running 4A on an ethanol system wastes your beads and your solvent at the same time.
How much do I need for ethanol?
Roughly 100 to 190 lb of 3A per 100 gallons, depending on how wet the ethanol is. As a worked example, 100 gallons of 191 proof carries about 4.5 gallons of water, near 37.5 lb, against a bead capacity of up to about 40 percent of bead weight.
Can I regenerate these rather than replace them?
Yes. Heat to 250 F, which is 121 C, under vacuum or purging with a carrier gas. That is the figure the bead supplier publishes. Do not overshoot it, because excessive temperature decomposes the beads and a decomposed bead does not come back.
4x8 or 8x12 mesh?
4x8 is the larger bead. Same 3A chemistry either way. Larger beads give lower pressure drop across the bed, smaller beads give more surface area per pound.
What does it cost?
$54.95 per 10 lb in 4x8 mesh and $49.95 per 10 lb in 8x12 mesh.
Can I buy the whole lot?
Yes, and it is the cheapest way to buy beads anywhere. $349.95 takes the remaining 80 lb of 4x8, which is $4.37 a pound, and $199.95 takes the remaining 50 lb of 8x12, which is $4.00 a pound. One lot of each, and when it is gone it is gone.
How has it been stored?
Sealed in bags, some with moisture indicator cards, in Bend, Oregon, which is about as dry a climate as this material could ask for. There is no regeneration caveat on it and none of it is sold as is.
Will you restock it?
No. This is clearance stock.
Do I need filters around the bed?
Yes, 10 micron sintered on both sides. Beads shed dust, and dust downstream of the dryer ends up in your product.
Can I use 5A instead?
No. A 5 angstrom pore adsorbs n-butane, propane and heavier hydrocarbons themselves. For extraction work it is 3A for ethanol and 4A for hydrocarbons.