Self-cleaning strainers

Self-cleaning strainers should be provided on all systems. The strainers should have stainless steel baskets with openings of 0.13 in (0.33 cm) diameter and be provided with a blow-off valve. 

The duplex or multi-basket strainer must stiU be watched to check for the need to swap baskets. Self-cleaning strainers may be used as an alternative to dual or multiple strainers where continuous operation is critical in the process system. Two methods of self-cleaning are illustrated in Figure 3.7 - one uses a brush and the other a scraper. Brush cleaning is suitable for most applications, with scraper types more specifically suited for handling high-viscosity products. 

Oil strainers may be of metal mesh and within the sump, in which case the sump must be opened for cleaning. Self-cleaning disc strainers are also used, the dirt falling into a drain pot or into the sump itself. There is an increasing tendency to provide replaceable fabric oil filters external to the compressor body, following automobile practice. 

Most analyzer sampling systems require a filter with at least one wire mesh strainer (100 mesh or finer) to remove larger particles that might cause plugging. Available filter materials include cellulose, which should only be considered if it does not absorb the components of interest. Sintered metallic filters can remove particles as fine as 2 ym, cellulose filters can remove down to 3 /on, and ceramic or porous metallic elements can trap particles of 13 ym or larger. When the solids content is high, two filters can be installed in parallel with isolation valves on each. Motorized self-cleaning filters are also available for such services. 

Windsor. Berks SL4 IRD Tel +44(0)1628 440906 Fax +44 (0) 1628 475667 Email info oxfordfiltration.com Web wAW.oxfordfiltration.com Manufacturer and Supplier of Simplex. Duplex Strainers and Self Clean filters for virtually any fluid duty... 

Simple strainers remove gross materials. These should not normally occur in public supply, but strainers are sometimes fitted to protect sensitive equipment or processes against breaks in the main, etc. The commonest form contains a stainless-steel wedge wire screen and is piped with a bypass so that the screen element can be isolated and removed for cleaning when necessary. If the load on the filter makes this kind of cleaning burdensome a self-flushing filter can be used. These can incorporate strainer elements down to 50 pm. 

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