FILTERS AND STRAINERS

FILTERS AND STRAINERS DOE-HDBK-1018/2-93 Miscellaneous Mechanical Components FILTERS AND STRAINERS When it is necessary to remove suspended solids from a liquid, the usual method is to filter or strain the liquid. The two methods differ only in the size of the mesh being used. Filtering removes the very small solids, and straining removes the larger solids. Because filtering and straining are for all practical purposes the same, this chapter will differentiate the two terms on the basis of application of the filter or strainer. EO 1.16 DESCRIBE each of the following types of strainers and filters, including an example of typical use. a. Cartridge filters d. Bucket strainer b. Precoated filters e. Duplex strainer c. Deep-bed filters EO 1.17 EXPLAIN the application and operation of a strainer or filter backwash. Introduction Filtration is a process used to remove suspended solids from a solution. Other processes such as demineralization remove ions or dissolved ions. Different filters and strainers are used for different applications. In general, the filter passage must be small enough to catch the suspended solids but large enough that the system can operate at normal system pressures and flows. Filters and strainers are used throughout most DOE facilities. They are used in hydraulic systems, oil systems, cooling systems, liquid waste disposal, water purification, and reactor coolant systems. Cartridge Filters Figure 20 illustrates a typical multi-cartridge filter. The cartridges are cylinders and usually consist of a fiber yarn wound around a perforated metal core. The liquid being filtered is forced through the yarn, which is approximately 1/2 inch thick, and then through the perforations in the metal core to the filter outlet, which can be at either end. A cartridge filter may include several cartridges, the exact number depending on the liquid flow rate that must be handled. ME-05 Rev. 0 Page 40