Questions You Should Know about Filter Press Feed Pump

The filter cake will begin to become wet, slimy and not as dry.  This is your indicator that the cloths need to be cleaned.  (see number 5 for cleaning info).  If you have already cleaned your cloths and your process has not changed but you are still getting slimy filter cake, it may be time to replace your cloths.  Cloth life varies from installation to installation and depends on such variables as frequency of cycles, proper cleaning and maintenance and the type of sludge that is generated.  Generally speaking for most installations cloths can last up to 6 months at the most.

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Expansion depends on a couple of factors.  First, if your press is already expandable, meaning you’re your press has a distance piece for expansion to a larger capacity, all you need to do is unbolt the distance piece and add additional plates in the 1-3 button sequence taking care that you add plates in even numbers.  However, if you have a Met-Chem press or your press has notched and bolted sidebars, then it can also be expanded by removing the sidebars and replacing them with longer sidebars and installing additional plates.  Please note that when adding plates, you must be sure to add them in the 1-3 button sequence in order to provide proper drainage.

There are several possible causes.  You might not have the proper cloths for you application or if you have been using the same cloths for an extended amount of time, you may have holes in the filter cloths.  The gasketed cloth may have slipped out of the grooves.  Or, perhaps, the cloth on the head plate may not  be properly secured.

Precoat and bodyfeed are two related applications.  Both of these special applications use diatomaceous earth (commonly known as D.E.), cellulose, perlite or fly ash, as a filtering aid when the solids in a slurry are extremely fine and free-filtering.  The filter aid helps to trap the fine solids that otherwise might flow through the filter cloths.  The processes of precoat and bodyfeed increase the clarity of the filtrate, provide for higher flow rates, more consistent runs, shorter cycles, dryer cakes, better cake release, and also help to protect and increase the life of the filter cloths.

The precoat process is performed before the slurry is pumped into the press.  A precoat system consists of a tank, mixer and pump.  The filter aid is mixed with water in the precoat tank.  It is then pumped into the press where it coats the filter cloths.  The filter aid rather than the filter cloths becomes your initial filter media.

During a body feed the filter aid mixes with the slurry in the holding tank prior to being fed into the filter press.  The filter aid becomes part of the slurry thereby providing a better filter cake.

If you have not made any recent changes to the plate stack (which is the number one reason this might occur), there are several possibilities.

You could have a build-up of solids on the sealing surfaces which will then need to be cleaned. 

Check to see if the hydraulic pressure is set to the recommended specifications.  If not, make the appropriate adjustment.

Another possibility is that there could be a wrinkle or hole in the filter cloth or the gaskets may be loose.

If you continue to have problems, contact your Met-Chem representative.

It’s a good idea to change your gaskets whenever you change your filter cloths.  Also, if you are getting excessive leakage out of the press while maintaining correct hydraulic closure pressure, this may be a sign that it is time to change your gaskets.

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Gasket life will depend on many factors, such as length of filtration cycle, temperature, and excessive closing force. Gasket replacement should take place if the gasket appears to be delaminating or shredding.  Also, if excessive temperatures exist and cycles are very long, the standard gasketing material may go into additional cure, causing it to harden slightly.  If  you continue to have a problem, contact your Met-Chem representative for an alternative.

If the press is leaking (around the locknut on the 470mm size or from the bottom leg drain holes on 630mm and larger size presses) during the start-up of the feed process, the problem is usually leakage past the center feed quad ring seal. The quad ring may not seal for several reasons.

First check for the cause:

Did the locknut on the outside of the press head loosen during shipment?  If so, tighten the locknut using a spanner wrench, pliers, or pipe wrench.

This depends on your process. Cloth selection is as much an art as it is a science. Based on our 1,000 years of combined experience and lab testing, we can make an expert recommendation to you. We supply cloths based on criteria you give us and based on sample processing we do in our lab. Should your process change, we recommend that your cloth type be evaluated for suitability.

The following is general information to help you understand cloths and how they work. For detailed questions, call our customer service department at 800.245..

Cloths for non-gasketed plates are hung over the plate, extending from top to bottom, and are held in place by eyelets that fit over the cloth-pins on top of the plates. With the non-gasketed plate, the filter cloth provides the seal between the plates. Leakage will occur during operation even though Evoqua supplies the non-gasketed plate cloths with latex edging. The latex will cut down the wicking action somewhat, but will not eliminate it.

The gasketed plate allows less leakage than the non-gasketed plate due to an O-ring seal around the chamber and filtration ports. The gasketed cloth has a high-density sash cord sewn around the cloth's perimeter that is caulked into a groove on the plate.

The type of cloth used is determined by the type of process or application performed by the filter press, the operating environment, and the performance required by the filtering media (filter cloths).

The filter cloths come in many different materials including polypropylene, polyester, cotton, and other synthetic materials. The cloths are made from monofilament fibers, multifilament fibers, or spun fibers. The smooth surface characteristic of monofilament fibers can help to improve cake release properties. The uniform circumference of monofilaments also enables fabrics to be produced with consistent pore sizes. Multifilament and spun fibers are produced by twisting several smaller diameter monofilament fibers together into a single strand. They are used to produce fabrics that require a very tight weave and fabrics where high flow rates are not critical.

Filter cloths also come in many different styles of fabric weave. ​

Mesh opening or pore size is also an important consideration when selecting the

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