This is the final article in a three part series on the use of carbon block in water filters.
Several steps comprise the carbon block manufacturing process but the process always starts with the approval of incoming materials. A good manufacturing process should include extractables testing for approval of all materials for use in drinking water applications and testing for each material’s critical performance characteristics prior to producing the carbon block.
Next, materials are blended prior to moulding or extrusion. Thorough blending is important to make sure a homogeneous mixture is introduced into the moulding or extrusion process.
In a typical moulding process, the material is introduced into fixed moulds, compressed and heated to form the sintered block. After cooling, the carbon block is removed from the mould, trimmed to size if required, and packaged or assembled into filter cartridges.
Essentially, extrusion utilizes the same mixtures as moulding but relies on a continuous forming process in which the material is conveyed by a screw-type auger and either heated in transit within the screw or heated in an external die. Several patented processes currently are in use to manufacture extruded products. After heating and forming, the material is cooled in a die and exits the process as one continuous cylinder of material. The extruded product then is cut to length and packaged or assembled into filter cartridges.
Both the moulding and extrusion process produce carbon block of similar characteristics and the basic processes are similar in nature with heating, compression to a specific density and cooling involved to produce the finished product.
Typical limitations involved in the manufacturing of carbon block are related to the production equipment available to produce a given size of block. Moulds and extrusion die sizes are fixed, so utilizing existing moulds and dies when possible helps reduce capital expenditure and lead time to obtain the finished product. Block typically is available in sizes from 1 to 4.25 inches in diameter and 2.5 to 40 inches in length.
In summary, carbon block is an effective and versatile filtration method for a wide range of applications. Additionally, a host of products are available from carbon block manufacturers, and blocks can be custom moulded or extruded to provide the sediment and chemical removal needs of the application.