BACKWASHABLE MICRO FILTERS

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The Filtrex Wafer and Candle

Our patented wafer boasts a number of advantages over other filtration media. It has a high open area ratio, allowing high flow over a smaller surface area. Depending on the application, each wafer has up to 2000 microgrooves etched on each of its arched surfaces, allowing for precise filtration and maximum utilization of the wafer’s surface area. Barring abnormal applications, the thermoplastic wafers are permanently reusable, which means no costly throw-away media like cartridges or paper, and no harm done to the environment.  They have the ability to self-clean in the back-washing cycle which minimizes system maintenance.

When stacked in perfect alignment over a hexagonal support core, the wafers form filter candles, which are capable of filtering particulate as mall as 5 micron. For even finer filtering capability, a pre-coat of Diatomaceous Earth (DE) can be added to the filter candles making them suitable for even the most demanding conditions.

The Filtration and Back Wash Cycle

Filtration Mode

The vessel consist of an upper and lower chamber. During the continuous service cycle, the unfiltered fluid enters from the lower chamber, flowing across the candles where filtration will occur.

Pre-coating is accomplished by circulating a slurry of filter aid like diatomites, cellulose or perlite in a clean liquid. (pre-coat tank to filter and back) The filter aid particles create a coat over the filter candle. This coating now becomes the filtering media supported by our filter elements. This action is greatly enhanced in the Filtrex-Heger units due to the unique support feature offered by the naturally occurring "ledges" created as a result of stacking the filter wafers. Preacoating takes about 3 - 4 minutes to complete and forms an evenly distributed cake along the length of the filter candle. Various grades of pre-coat material is used to achieve the desired clarity (fines removal) and flow characteristics. Pre-Coat body feeds are normally injected during service in order to enhance the service cycle time.
BACKWASH CYCLE
When back-washing is initiated, the self-contained reservoir (upper part of unit) is pressurized with air, nitrogen or any gas that is compatible with your process and does not pose a risk to people or the environment. Pressures range from 80-120 psi (5 - 8 bar). Once pressurized, the drain valve (bottom) is quickly opened, causing the fluid in the vessel to flow in reverse direction at extremely high velocities. The kinetic energy causes the spring loaded compression plate to open, causing the filter wafers to loosen and momentarily separate. This action cleans the elements and the vessel very fast (15 seconds) and with extreme efficiency. The Backwash cycle takes 15 seconds to complete. If a rinse cycle is deemed to be necessary another 15 seconds will be needed. Once this is done the filter is ready for reuse. standard cycle begins again...

Depending on the application, the Heger-Filtrex candles are grouped into a vessel, which contain anywhere from a single candle to as many as several hundred.

The vessel consist of an upper and lower chamber. During the continuous service cycle, the unfiltered fluid enters from the lower chamber, flowing across the candles where filtration will occur.

The process water enters the candles through the microgrooves where the contaminants are intercepted, and then flows upwards through the cavities in the wafer candles. The filtered fluid is transported through these cavities into the upper chamber and out to the service connections. As the service cycle continues, the contaminants will cake on to the candle surface, ultimately causing the differential pressure between the two chambers to increase until it reaches a user-defined value, at which point the backwash cycle will be initiated.

Once back-washing is initiated, the clean chamber is pressurized using air, or other gas media, to ranges between 50-120 psi. The drain valve is opened, and the pressurized fluid flows in reverse at high velocity. This creates instantaneous compression of the candle spring, which separates the wafers and breaks up the contaminant cake, cleaning the filter in under a minute using a minimal amount of the clean fluid. Once clean, the service cycle begins again.

All of our filtration systems are individually tailored to meet your specific needs. Heger-Filtrex has built a reputation based on performance, reliability and customer satisfaction throughout the world. Contact us today with any questions regarding our products or services.

contact us for your application filter@hegerpumps.com

or call +1 562-989-5432