GB654559A - Improvements in or relating to apparatus for the treatment of water - Google Patents

Abstract

654,559. Electric tests and measurements. FILTRATORS, Ltd., and STREATFIELD, E. L. Nov. 15, 1948, No. 29578. [Class 37] [Also in Group I] Apparatus for treating water by causing it to flow through a bed in which its chemical condition is changed, includes means for withdrawing samples of water from a point in the bed past which the water flows appreciably before it leaves the bed, means for withdrawing further samples of water from a second point at which the water has passed a further distance through or completely through the bed, and apparatus arranged to be acted upon by the samples and responsive to variations in their relative chemical condition due to partial exhaustion of the bed resulting in incomplete treatment of the sample taken from the point past which the water flows first. In the arrangement shown in Fig. 1, a chamber A contains abed B of cation-exchanging material such as a carbonaceous zeolite, supported on an inactive bed C of gravel or the like. Porous sampling pots E are arranged within the bed B above the outlet end, and similar pots F are arranged within the bed C. Water from the pots E flows through a pipe E<SP>2</SP> to a conductivity cell G, and water from the pots F flows through a pipe F<SP>2</SP> to a conductivity cell H. The cells G, H are arranged in a Wheatstone bridge circuit supplied from a source A<SP>3</SP> of alternating current and including resistances K, K<SP>1</SP> and an ammeter L. While the water flowing through the two cells is of the same conductivity the ammeter L gives a zero reading, but when the bed A is nearing exhaustion the cells will have a difference in conductivity and the ammeter reading will indicate a need for regeneration. Means may be provided so that the water reaching the cell H at any moment came from substantially the same portion of the water flowing through the chamber A as the water flowing at the same moment through the cell G. The apparatus may include a relay operated automatically, when the Wheatstone bridge circuit becomes unbalanced to a predetermined degree, to bring into operation apparatus for regenerating the bed B. The relay may be of a delayed-action type, inoperative on the occurrence of a mere transient unbalancing of the bridge circuit. In the arrangement shown in Fig. 2, the pipes E<SP>2</SP>, F2 deliver water, respectively, through two cells M and N for pH measurement. The cells are of the type containing a calomel reference electrode and a " glass " electrode. The electrodes are connected to apparatus O which may include thermionic amplifying apparatus, an indicator O<SP>1</SP> positioned in accordance with the relative values of the E.M.F. generated by the cells, and a relay switch or the like controlling a circuit through conductors P, whereby regenerating apparatus is brought into operation on a predetermined difference occurring in the values of the E.M.F. generated by the cells.