Patent ID: 7297235

Claim:
Apparatus for forming fibrous filter elements, which comprises: a reservoir for a body of aqueous liquid, said reservoir being provided with a first liquid level sensor to output a first sensor signal; means for supplying make-up water to the reservoir via an inlet valve; a mixer for mixing fibers with liquid from the reservoir to form a slurry, the mixer comprising a tank provided with a second liquid level sensor to output a second sensor signal; a holding tank for receiving slurry from the mixer and provided with a third liquid level sensor to output a third sensor signal; at least one molding rig for molding fibrous filter elements from the slurry by separation of the fibers from a major proportion of the aqueous liquid of said slurry; means for supplying slurry from the holding tank under pressure to the or each molding rig; means for returning unused slurry from the or each molding rig to the holding tank; means for returning to the reservoir from the or each molding rig aqueous liquid that separates from the fibers as fibrous elements are molded; and control means arranged to monitor the volume of liquid in said apparatus on the basis of received first, second and third signals from said first, second and third liquid level sensors, and the control means, if the volume of liquid is below a target value and aqueous liquid returning to the reservoir being insufficient to maintain the volume of liquid in the apparatus above a target value, to open the inlet valve for admission of make-up water to the reservoir.