SIPHON TYPE AUTOMATIC BACKWASHING APPARATUS IN FILTER APPARATUS

PURPOSE:To maintain filtering capacity for a long period of time, by a method wherein a filtrate is stored as backwashing water in a siphon type automatic backwashing apparatus in a filter apparatus and the operational height of a siphon tube is made adjustable to effectively carry out backwashing and cleaning of a filter material. CONSTITUTION:In a filter apparatus for using a filtrate obtained by filtering filthy water through a filter material as backwashing water, a siphone tube 18 for backwashing operation is bent into an M shape and a vinyl pipe 20 having a small diameter is mounted therein in such a manner that it pieces the upper part of a first chamber 18A and the upper end part of a weiar 18b in a second chamber 18B and is present between the weir 18b and the upper part of a downwardly opened tube 17a and a long slot 21 is opened by drilling to the under surface of a bent part thereof turning from a downward direction to an upward direction. When pressure loss of a filter material is increased by succeeding operation of filtering treatment, the small pipe 20 withdraws raw water from the slot 21 by siphon operation and air in the first chamber 18A from the leading end thereof in a mixed form to form a perfect backwashing condition and the filter material is backwashed and cleaned by a stored filtrate to keep the filtering capacity of the filter material for a long period of time.