Sand bed filter tank for liquids - has angled baffles along walls defining chambers for decanting sand entrained during reverse flushing to clean bed

摘要

A sand bed filter tank has a flat bottom through which only liq. can pass and >=1 wall forming an overflow. Along this wall within the tank, an angled baffle plate is arranged to form a decantation chamber opening at its lower part intot he tank. The baffle plate is pref. mounted by >=2 supports having slots which receive the lower part of the baffle plate and sliding rods whose ends are fixed to the baffle plate. The supports are pref. in the form of stirrups clamped on to the upper edge of the wall of the tank. Each sliding rod pref. has an adjustable stop ring which rests against a pivot in the support, through which the rod passes. The baffle plate pref has a deflector on its lower edge and resting against the wall of the tank to return the decanted sand to the bed. The filter is used in the purification of liqs., esp water contg fine particles in suspension. Such filters require periodic reverse flushing to clean them, and the decantation chambers greately reduce the loss of sand entrained by the reverse flow of water during flushing, enabling the sand to settle out before the water passes over the overflow and to return to the bed.