The very feature that distinguished the plate filter, i.e. the formation of a cake on the upper surface of the element only, makes this type that much more difficult to operate when it comes to dry cake removal. Wet discharge is as easy as with a leaf filter, provided that the sluicing reaches every part […]
The leaves in a pressure leaf filter hang, or are held, vertically and, while this permits filtration on both sides of the leaf, it also means that the accumulating cake can easily fall off the leaf for lack of support below the cake. This problem is overcome by mounting the filter elements horizontally, when they […]
The leaf filter incorporates an array of flat filter elements, with filter media on both sides of the element, each one parallel to its neighbours and hanging, equally spaced, from a horizontal support that is also the filtrate offtake pipe. The array is enclosed in a pressure vessel, usually circular in cross-section, and there is […]
The last few parts of this Section (3J to 3M) have been concerned almost entirely with the clarification of a flow of fluid, usually to remove contaminants from it, and very often in a utility function. Most of the remaining parts are now concerned with process filtration, in which the filtration process is intended to […]
A small but important group of what are, in effect, single cartridge filters are operated in such a way that they can be continuously cleaned by an automatically functioning mechanism. These are called self-cleaning filters (and in some industries, automatic filters – although a wide range of filter types can be arranged to operate automatically). […]
The most common form of cleaning is to reverse the flow of fluid through the filter medium, and so to blow the surface clear of collected contaminants. As this requires filtration to stop, a satisfactory system employs at least two filters, side by side in a duplex arrangement, with the piping and valves around the […]
Most filter elements, including all of those described in Sections 3K and 3L, are intended to be cleaned free of accumulated contaminants, wherever this is pos sible, simply from the economic viewpoint of avoiding waste. This is done either by removal from their housings for cleaning in another place, or by cleaning in situ, but […]
A constructed cartridge somewhat different from those just described is the lenticular disc filter – the prime difference being that the components of a complete element are capable of undertaking filtration on their own, and are in fact used in that way. The lenticular disc is a circular element made from two discs of filter […]
The final group of surface filtering cartridges is made up of individual compon ents that, by themselves, could not act as a filter medium, but when assembled into a generally cylindrical shape create an external surface carrying an array of slots, whose width defines the pore size of the filter. Probably the simplest such array […]
A foam is created when a mass of gas bubbles is evenly distributed throughout a quantity of liquid, in such a way that the gas occupies almost all of the final volume, surrounded by the liquid in the walls of the bubbles. If the liquid then sets solid, a very porous mass is created, which […]
