High efficiency particulate media

The offgas treatment systems and agent filter area (AFA) have filtering systems that will produce waste. These include particulate filter w aste, iron sponge absorber waste, prefilters, and high-efficiency particulate air (HEPA) and activated carbon filters. Activated carbon is used as filter medium in... 

The most representative test is the standard of Underwriters Laboratories Inc. for High Efficiency Particulate Air Filter Units (UL 586). These units will generally consist of a filter medium of glass fiber or other inorganic material and a frame of metal constmction. It is possible to utilize wood but it will have a flame spread of 25 or less. When tested in accordance with UL 723, test method for surface burning characteristics of building materials, UL 586 tests the filter, frame and supports as a unit. It utilizes a 4" blue flame with direct impingement for 3 minutes. It must remain intact. The UL 586 test apparatus units are up to 2 x 2. The typical filter used in the modem cleam-oom are 2 x 4. These units are available in this size from major manufacturers constmcted in an identical fashion to those tested. They will not be labeled since they are beyond the scope of the test. These are the most appropriate units for use in cleam-ooms for the semiconductor industry. 

In the true gravity case, pumps are not used. If, however, the liquid is highly viscous, to achieve efficient operation, pumps are required to force the fluid through the pressure filters. The pump can be considered essentially as a press with a plate-and-frame filter. The plate-and-frame filter consists of a series ot frames over which the filter medium is stretched. A centrifugal basket of fine mesh is another method of particulate removal. 

Particulate sorbents are available almost exclusively in the shape of micrometersized beads. These beads are packed in columns and represent currently the most common stationary phases for high-performance liquid chromatography (HPLC). Despite their immense popularity, slow diffusional mass transfer of macromolecular solutes into the stagnant pool of the mobile phase present in the pores of the separation medium and the large void volume between the packed particles are considered to be major problems in the HPLC of macromolecules, frequently impairing their rapid and efficient separation [1]. 

The high heat transfer efficiency makes the unit, using sand as a particulate, suitable for heat treatment applications such as pasteurization, precooking, insect eradication, and other applications in which moisture removal is not apriority. With zeolites as the transfer medium, moisture removal rates double, thus bringing drying efficiency up to the standards. 

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