Activated carbon is a highly versatile adsorbent used in hundreds of different fields from industrial treatment processes to gas filtration, food production to mining. The success of an activated carbon is directly related to its physical particle size as much as its degree of chemical activation.

While activated carbon sizes are generally expressed by the term "Mesh" in the sector, the "Millimeter (mm)" unit is taken as the basis in process engineering and filter designs. Choosing the wrong size of carbon can lead to premature clogging in the system, excessive pressure drops, or insufficient treatment efficiency. In this article, we will examine in detail the concepts of mesh and mm in activated carbon, the most commonly used size comparisons, and which size should be preferred in which process.
  1. What is Mesh Size? How is the Relationship with Millimeters Established?
Mesh is a unit of measurement used in international sieve standards. In simple terms, it represents the number of square holes (openings) located on a 1-inch (25.4 mm) linear line.
  • As the Mesh Value Increases, Particle Size Decreases: For example, while a 4-mesh sieve has 4 holes per inch (holes are large), a 30-mesh sieve has 30 holes (holes are much smaller).
  • Range Expression (e.g., 8x30): In activated carbon products, sizes are usually shown with a double number such as "8x30" or "6x12". This expression indicates that the carbon particles pass through the 8-mesh sieve (largest particle limit) but remain on top of the 30-mesh sieve (smallest particle limit).
  1. Activated Carbon Mesh - Millimeter (mm) Comparison Table
The following table shows the nominal equivalents in millimeters of the standard mesh sizes most frequently encountered in activated carbon procurement and technical specifications:
Standard Mesh Size Millimeter (mm) Equivalent Range General Description / Form
4 x 8 Mesh 4.75 mm – 2.36 mm Large Granule / Coarse Particle
6 x 12 Mesh 3.35 mm – 1.70 mm Medium-Large Granule
8 x 16 Mesh 2.36 mm – 1.18 mm Standard Medium Granule
8 x 30 Mesh 2.36 mm – 0.60 mm Liquid Phase Classic Granule (GAC)
12 x 40 Mesh 1.70 mm – 0.42 mm Fine Granule
20 x 50 Mesh 0.85 mm – 0.30 mm Ultra-Fine Granule / Micro Pellet
200 Mesh (-200) < 0.075 mm (75 Microns) Powdered Activated Carbon (PAC)
325 Mesh (-325) < 0.045 mm (45 Microns) Ultra-Fine Powdered Activated Carbon
Note: In pellet (cylindrical) activated carbons, sizing is expressed directly as a diameter in mm (e.g., 3mm, 4mm, 5mm pellet carbons).
  1. Sectoral Application Areas of Activated Carbon According to Their Sizes
📐 4x8 Mesh (4.75 mm – 2.36 mm) Due to its large-particle structure, it exhibits minimum resistance against air or liquid passage in high-flow lines.
  • Application Areas: Industrial odor control towers with high air flow rates, gas phase purification, fixed-bed large treatment filters, and vertical adsorber systems where pressure drop is strictly undesired.
📐 6x12 Mesh (3.35 mm – 1.70 mm)
  • Application Areas: It is the industrial standard, especially for Gold Recovery (CIP and CIL processes). It allows dense mineral pulp (slurry) to flow comfortably through the carbon bed without clogging the screens and minimizes mechanical loss during carbon transfer.
📐 8x16 Mesh (2.36 mm – 1.18 mm)
  • Application Areas: Preferred in CIC (Carbon-in-Columns) adsorption columns used after heap leaching in gold mining. It also plays a role in specialized gas mask filters and catalyst carrier systems requiring high surface area.
📐 8x30 Mesh (2.36 mm – 0.60 mm) It is the classic Granular Activated Carbon (GAC) size most widely used in liquid phase and water treatment applications worldwide.
  • Application Areas: Industrial and domestic water treatment filters, removal of chlorine, organic matter, taste, and odor in drinking water plants, protective filter tanks prior to Reverse Osmosis (RO) membranes. It offers an optimum balance of flow rate and adsorption speed.
📐 12x40 Mesh (1.70 mm – 0.42 mm)
  • Application Areas: Used in small cartridges of domestic water treatment devices, aquarium filters, and specialized process liquid purification lines where water contact time is short but rapid adsorption is targeted.
📐 20x50 Mesh (0.85 mm – 0.30 mm) Although not as fine as powdered carbon, it is the smallest sized among granular carbons. It offers an ultra-high external surface area.
  • Application Areas: It is the main raw material, especially for Carbon Block (CTO) Filter Production used in domestic and industrial water treatment devices. Combining with binder polymers, it ensures the production of compact, high-performance block filters.
📐 200 Mesh and 325 Mesh (Powder Form / < 0.075 mm) It is fully pulverized activated carbon (PAC). It is applied by mixing directly into liquids (batch process).
  • Application Areas: Color and impurity removal in the food industry (citric acid, collagen, sugar syrups, fruit juices), in the pharmaceutical industry (API purification), clarification of chemical solutions, and lowering instantaneous high COD (Chemical Oxygen Demand) loads in wastewater plants.

Conclusion: Choosing the Right Size for Your Process
As the particle size decreases in activated carbon, the geometric external surface area increases and the adsorption speed (kinetics) reaches its maximum. However, decreasing the size causes ventilation fans or water pumps to consume more power (high pressure drop). Therefore, the most accurate engineering approach is to select the smallest carbon size suitable for the flow rate and pressure limits of your process.

As Carbontech, we offer all the activated carbon sizes required by the industry, from 4x8 mesh to powder form, from 3mm-4mm pellet carbons to mining grade special GOLD series 6x12 and 8x16 mesh sizes, with our extensive stock range.

To determine the mesh size best suited to the hydraulic calculations of your project, request product samples, and receive corporate technical support, you can contact our expert engineering team at any time.

🌐 Our Website: www.carbontech.net.tr
📩 E-mail: info@carbontech.net.tr
📞 Phone / WhatsApp: +90 552 017 11 04