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CHAPTER XVII 



the cloths being locked to the plates by a male and female screw combination 

 passing through the central hole. The water conduit is shown at w, and 

 the washing exit at a, in an upper corner of the plate. In this type cocks 

 are not provided for the escape of the dilute juice from each alternate plate, 

 but the conduit formed by the transverse openings is controlled at one end 

 by a valve discharging into a gutter. At h are openings similarly controlled, 

 which admit of the escape of the air. The assembled press is arranged 

 similarly to the plate and frame press, the method of washing being the same. 



The Leaf Filter. — The Philippe type of leaf filter is indicated in perspective 

 in Plate XXV. It consists essentially of a rectangular box with double 

 inclined bottom. Arranged near the top of the box is a horizontal frame, 

 in which are supported a number, usually about twenty to thirty, rectangular 

 wire or pressed steel frames or baskets. These frames are covered with 

 cloth pockets, which make a tight joint with the horizontal frame. The 

 cover of the box is a hinged lid, which carries a number of cocks, one for 

 each basket. The lid on closing makes a tight joint with each filtering 

 element. Dirty juice admitted to the box by the pipe passes to the interior 

 of the baskets, the solid matter being caught on the cloths. When filtration 

 ceases the dirty liquor remaining in the box can be discharged by a cock 



b'^ 



These presses are made in a great variety of shapes. Instead of being 

 rectangular the elements in some designs are cylinders, and many variations 

 are possible without altering the principle. By European makers the frames 

 are regularly made 0-7 metre square, thus giving a filtering area of nearly 

 one square metre per element. They are operated under a head of liquid 

 up to eight feet. 



Kelly Press.— The Kelly press, Plate XXV (U.S. patent 864308, 1907) 

 is a leaf filter designed for the pressure filtration of scums. It consists of 

 a cylinder mounted on an inclined frame. The filtering elements are made 

 up of wire frames covered with cloth, and are usually spaced four inches 

 apart ; they are supported on a travelling carriage mounted on wheels. 

 Each element has an individual outlet. Washing of the cloths and discharge 

 of the cake is effected after running the whole filtering system down the 

 runway. The cloths are washed by the impact of a jet of water. But one 

 joint is ever required to be made. This press is very largely used in the 

 American beet sugar industry. 



Sweetland Press. — The Sweetland press, Plate XXVI (U.S. patents 

 885398 and 887285, 1908), is another type of leaf filter. Its peculiarity 

 lies in the " clam shell " arrangement, whereby the press is opened, allowing 



