Choosing a Mesh Size: 4×8 vs 6×12 vs 8×30

Two buyers can order the same activated carbon grade and get completely different results — because they chose different mesh sizes for the same duty. Here is a practical guide to reading mesh designations and picking the right fraction.

How mesh designations work

A designation like 6×12 means the granules pass through a 6-mesh screen (about 3.35 mm openings) but are retained on a 12-mesh screen (about 1.70 mm). So “6×12” is a size window: every granule is between roughly 1.7 and 3.4 mm. The two numbers always go coarse-to-fine.

We produce three standard fractions:

The trade-off: speed versus resistance

Smaller granules expose more outer surface and shorten the path contaminants travel to reach the pores — so adsorption is faster. But smaller granules also pack more tightly, so water pushes through with more resistance — pressure drop rises, and beds can channel or clog if the water carries sediment.

• Choose coarse (4×8) when flow rate is high, contact time is generous, or the water carries suspended solids.
• Choose medium (6×12) for most fixed-bed columns — municipal filters, industrial polishing, general purification. If in doubt, start here.
• Choose fine (8×30) when contact time is short and kinetics must be fast — point-of-use filters, final polishing stages, compact equipment.

Why fines content matters more than people think

Whatever fraction you buy, ask about the sub-sieve fraction — dust and broken granules finer than the nominal window. Fines migrate through beds, blacken the first flush, and abrade pumps and valves. The standard check is the mesh-325 test: our independent Sucofindo reports show nil passing mesh 325 on all three grades, across three separate production batches.

Not sure which fraction fits your system? Describe your column, flow rate and duty — we will size it with you before you order.