Water Well Journal
Issue link: http://read.dmtmag.com/i/681918
as a "typical" value of removal. Depth filters can be produced using several methods. The most common types are fiber filters and sintered fil- ters. Fiber filters are either spun or woven into a cloth or felt. A common example of a fiber filter is shown in Figure 7. These inline sediment and carbon filters are used extensively in residential applications as "point of entry" (POE) or "point of use" (POU) devices to filter and remove unwanted sedi- ments or contaminants or to correct taste and odor issues with water as it enters the residence or appliance. Depth filters are commonly rated in such nominal filtration values as 5 microns, 20 microns, 50 microns, and 100 mi- crons, and in flows between 1 GPM up to 30 GPM, depending on the size and type of the unit. Sintered filters such as ce- ramic, metal, or porous plastic filters are formed by fusing particles together under heat and pressure. The spaces be- tween the particles create the flow path or pores of the filter. Inline ceramic filters, often used for drip irrigation applica- tions, are an example of sintered filters. LARGER SOLIDS SEPARATION In addition to the straining and barrier methods of solids removal, a final example of removal of unwanted material in a flow stream is shown in Figure 8. Commonly known as a sand or centrifugal separator, it uses centrifugal force with gravity to separate and remove sand and other particles up to 98% in sizes of 74 microns (200 mesh) and larger from a water flow. Although these units may occasionally remove some material slightly smaller than 74 microns, the perform- ance rating is usually based on that value since the gravity of smaller particles vary greatly. As shown in the figure, as water enters the side inlet of the separator, the water is accelerated to create a spin around a central chamber. This resulting velocity physically separates heavier and larger particles, such as sand and most larger debris, from the water through centrifugal force. The water is then discharged out through the top of the unit with the settled material allowed to settle down to the bottom of the separator through the specific gravity (weight) of the material. Over time enough accumulation of this material is generally gained to initiate a "blowoff" sequence. This typically consists of an automatic or manual valve on the lower end of the separator (purge) to provide cleaning of the solids chamber. A blowoff sequence is generally initiated through an automatic timer waterwelljournal.com 48 June 2016 WWJ ENGINEERING from page 47 2215 SOUTH VAN BUREN · ENID, OKLAHOMA, USA 73703 · PHONE 580.234.4141 āGRPVDOHV#JHIFRFRPāLQWVDOHV#JHIFRFRP ·ZZZJHIFRFRP *()&2,1&DQ$VWHF,QGXVWULHV&RPSDQ\ Learn How to Engineer Success for Your Business Engineering Your Business: A series of articles serving as a guide to the groundwater business is a compilation of works from long- time Water Well Journal columnist Ed Butts, PE, CPI. The hardback book features 37 complete "Engineering Your Business" columns and the figures and tables that originally ran with the articles. The columns cover the groundwater industry and are divided into six areas: contractor classroom, getting started, troubleshooting pumps, rehabilitation, business basics, and tricks of the trade. Visit NGWA's Online Bookstore at www.NGWA.org for more information.