Allied Filter Systems Ltd is able to offer two types of self cleaning filters:
Wedge Wire Self Cleaning filters
The liquid flows from the outside to the inside of a wedge wire screen and leaves the filter housing through the higher placed outlet. A seal is located between the lower placed inlet and the upper outlet, limiting any cross contamination between lower (dirty) side and upper (clean) side
Particles are retained on the outside of the screen and are continuously removed from the filter element by a flexible scraper blade. The contaminants are directed to the sump by a laminar flow in the filter and collected in the bottom section of the filter housing.
This collection chamber may be purged either manually or automatically through a valve. An automatic purge system can be set up including an actuator and a time controller or pressure differential initiated valves. The installation of a manual by pass function is advised. Clogging of the filter is almost impossible, because of the special construction of the wedge shaped filter element wires. The filter fineness is established by the width between the wedge formed wires.
DSF (Disc Scraper filters)
The liquid or solids suspension enters through the inlet at the top of the filter, flows freely through the apertures in the cleaning disk and is filtered by the filter screen. Contaminants larger than the micron rating will be stopped on the inside of the filter screen surface, and cleaned liquid exits through the outlet in the lower part of the filter.
The collected contaminants are removed from the inside of the surface by a manually initiated, timer initiated or delta P initiated pneumatic actuated annular scraper. This results in a cleaned filter surface with limited pressure drop and no liquid loss. The continuing flow of product prevents contaminants from returning upwards.
Contaminants are physically and positively pushed into a bottom collection chamber where they accumulate, ready for elimination when the bottom mounted purge valve is actuated. This can be carried out manually or automatically. At pre set intervals the collected solids are purged, either manually or automatically, depending on the degree of automation required. This operation can be carried out without stopping the process.