Suction Self-Cleaning Filter

Automatic filter, with a self-cleaning mechanism driven by an electric motor including the Following processes: 1. Filtering process: Raw water flows into the filter through the cylindrical filter element from the inside-out, causing particles to accumulate on the inside screen surface which causes the development of a "filter cake". The accumulation of the filter cake causes pressure differential to develop between the filter inlet and outlet. A pressure differential switch senses the pressure differential across the screen and when it reaches a preset value, the cleaning mechanism is operated. 2. Cleaning process: The self-cleaning process begins when the pressure differential across the screen reaches a preset value or an (adjustable) amount of time has passed. Cleaning of the filter's fine screen is carried out by the suction scanner which is a motor driven assembly that rotates while also moving linearly. It consists of a central tube with tubular nozzles equally spaced along the length of the central tube. An exhaust flush valve connects the internal cavity of the suction scanner to atmospheric pressure outside the filter body. By opening the exhaust valve, the differential pressure between the water inside the filter and the atmosphere outside the filter creates high suction forces at the openings of each of the suction scanner nozzles. This suction force causes water to flow backwards through a small area of screen in front of each nozzle, pulling the filter cake off the screen and sucking it into the suction scanner and out-through the exhaust valve to waste. The driving mechanism rotates the suction scanner in a slow, controlled motion. The cleaning cycle is completed in approx. 30 seconds, during this time the nozzles cover 100% of the screen removing the filter cake from the entire screen surface, during the self-cleaning cycle, filtered water continues to flow downstream of the filter.