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FILTER PRESS
A FILTER PRESS is essentially an alternate assembly of FILTER PLATES and FILTER MEDIA which are compressed in a framework called the FILTER CHASSIS. The plates are constructed in such a way that the compressive force is applied only to the perimeter of the filter media and the highly compressed edges then act as gaskets and prevent leakage of liquid from the interior of the assembly There are of course many variations on this theme but only those which relate to the filters described in this brochure are detailed below.
 
The filter plates are a very Important part of a filter press because they provide the essential mechanical support for the filter media as well as the means whereby the liquid is distributed to, and collected from, those media. They are designed to achieve these objectives with the minimum of pressure differential when the filter is in operation.
 
Our plates feature one or other of two basic types of support surface. The first consists of a regular pattern of raised ribs and this form of construction is found in plates which are produced by casting or mouldings. With this type of plate the filter media are supported by the tops of the ribs while the liquid moves freely along the channels between them.
 
The second type of support surface consists of flat sheets having a large number of perforations and this is found mostly in plates which are of fabricated construction Such plates usually consist of an open framework to which are attached two perforated sheets separated by spacing devices. With this type of plate the filter media lie flush against the flat sheets while the liquid moves freely between them.
 

 

 

FILTER MEDIA

The filter media used in our filter presses are usually either cellulose mats or filter papers but, in certain instances, woven fabrics, porous plastics, etc may be used. Filter papers act mainly as fine sieves or as supports for beds of filter aid powder which may need to be added to the filtering liquid to improve Its filterability Cellulose mats can provide a much finer degree of filtration than filter papers due to depth filtration whereas filter papers offer economy.

The choice of a suitable filter medium is determined by various factors such as the size, nature and clogging characteristics of the insolubles to be retained, the chemical properties and viscosity of the liquid. the economics of the operation, etc. Some of these factors cannot be predicted and this is why our laboratory facilities and extensive experience of assessing filtration problems are a valuable resource.

It is a common belief that, in a filter press, the filtering liquid passes through the first sheet of filter medium, then through the second one and so on, but this is a fallacy. All the media operate in parallel and thus the more of them that are used the higher is the rate of flow through the filter and the larger is the total volume of liquid that can be filtered before the media are clogged.

 

For further information, email sales@britishfilters.co.uk or phone 01752 703900
 

Copyright © British Filters Limited 2007. All 3rd party trademarks are hereby acknowledged.
 

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