Fig. 145a.—Contact Bed Apparatus.
The syphons manufactured by Messrs. George Jennings, Ltd., actuated by air-valves as described under the heading of “Dosing Apparatus,” can also be adapted for filling and emptying contact beds.
Fig. 146.—Contact Bed Apparatus.
The Enock apparatus for contact beds, [Fig. 146], manufactured by Messrs. A. G. Enock and Co., Ltd., is a simple device working on the principle of the ball valve. A float, which takes the place of the ball, is raised by liquid entering a pit, which pit is outside the bed or tank which has to be emptied by the valve. The valve is attached to a vertical rod in connection with a horizontal weighted lever, at the other end of which the float is fixed. When a tank is full, it flows into the float chamber, and the rise of the liquid in this pit lifts the float and opens the valve, thereby allowing the contents of the tank to escape. The float pit then slowly empties itself by means of a small outlet pipe, and the valve closes so that the tank is ready to receive more liquid. This apparatus can be arranged so as to fill a number of beds in rotation, the inlet valve to each pit being either opened or closed as required by the overflow of liquid from each contact bed in turn. The outlet valves to the contact beds are similar to those already described and if the first beds are filled in rotation, no further connection between the apparatus in the lower beds will be required, each valve working absolutely independently of the others.
The chief advantage claimed for this type of apparatus is, that it can be adjusted so as to suit any required level of liquid in any particular bed.