5 it is made up of smaller particles that cling together to form a porous mass. If we now examine these smaller particles with an electron microscope, we see that they contain thousands of tiny needlelike attapulgite crystals. Scientists have calculated that one pound of attapulgite has about 13 acres of surface area. It is clear that residence time, mentioned above, is required because the fuel must have enough time to penetrate the clay particle where the surfactant can be adsorbed onto the surfaces of the crystals. Extremely small dirt particles in the sub-micronic range are also adsorbed. This is why the oil industry and most filter manufacturers keep the flow rate per standard cartridge very low – from 5 to 6 gpm, but never higher than 7 gpm. The industry is well standardized on 18” long cartridges, 7” diameter. Referring once again to the construction of a clay particle, it was mentioned that the individual grains are made up of very small particles that cling together. The grains will not break down under normal conditions, but water can cause this to happen. To deter breakdown in the presence of water Parker Velcon uses an oventreated grade of clay, known as Low Volatile Materials (LVM). The improvement in operating life of coalescer cartridges when clay is installed is dramatic. At one location, 50,000 gallons were clogging Parker Velcon filters “9” series cartridges. Life jumped to 4 million gallons after clay was installed and the clay cartridges lasted 8 million gallons. In another installation, regular “6” series cartridges were lasting only 200,000 gallons. After clay was installed, life went up to 16 million gallons. The improvement in filter membrane color ratings is just as dramatic as the improvement in coalescer life. Two types of cartridges are available for clay vessels. One is a bag cartridge which contains a given quantity of clay inside a cloth bag. The second cartridge is a rigid canister, which contains the same clay. Parker Velcon only produces the canister type cartridges because they provide a more effective sealing mechanism between cartridges when they are stacked on top of one another in the clay vessels. This cuts down on by-passing caused by folds of the cloth of the bag cartridge. Since the flow rates on clay cartridges are quite low, it is possible to have a significant amount of by-passing from relatively small apertures between the bag cartridges. Also, some competitors’ bag cartridges and canisters contain less efficient 30–60 mesh clay. We encourage customers to use Parker Velcon’s canister type cartridge (with 60–90 mesh) for the best performance and highest efficiency of clay treatment vessels.
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