Patent GB-485386-A (GB)
Title: Improvements relating to the testing of the hardness of water
IPC: G01N33/18
Filed: 1936-11-21
Abstract: 485,386. Photo-electric apparatus for testing hardness of water; water-softening plant ; valves for reciprocating pumps. PERMUTIT CO., Ltd. Nov. 21, 1936, No. 31950. Convention date, Nov. 22, 1935. [Class 40 (iii)] [Also in Groups I, XXVIII, XXIX, and XXXV] Relates to apparatus for testing the hardness of water, and for automatically controlling water-softening plant by the testing instrument. According to the invention, a mixture of soap and the water to be tested is continuously formed, agitated, and caused to flow in such a path relatively to a source of light and a photoelectric cell that light rays strike the cell if the water is hard but, if a voluminous lather is formed, are cut off or diffused by the lather. The cell may be connected to an instrument of the galvanometer type, tc give an indication of the water hard ness, or may through a relay initiate the reconditioning cycle of a softening plant when the water becomes hard In the apparatus shown, water to be tested and soap solution, in predetermined proportions, are drawn from a tank 60 by motordriven pumps 106, 94, and the mixture is delivered through a pipe 37 to an agitating box 30, in which is a rotary stirrer 32, Fig. 4. If the water is soft, a bulky lather is formed, which is strained by a screen 31 and flows into a trough 20 having slots 22 in its sides. The lather is held up in part by a dam 23, and the liquid mixture flows over a weir 24 into a discharge pipe. Light is directed from a lamp 45 through the slots 22 on to a photo-electric cell 40. If the water is sufficiently soft, the lather formed intercepts the light, but otherwise the liquid flows below the dam 23 without affecting the light. Thus a change from softness to hardness is indicated by an instrument 55 connected to the cell. In a modification, Fig. 10 (not shown), light is reflected from the surface of the mixture, and if the water is hard, falls on a photoelectric cell. When there is lather on the surface, the light is diverted from the cell by diffuse reflection. In this construction, agitation is effected by blowing air through the mixture. The pumps 106, 94 which effect the mixture of measured quantities of the water and soap solution are associated with a valve structure which connects the pumps to the respective liquid containers at the beginning of each suction stroke, and to the discharge pipe 37 at the beginning of each discharge stroke. Pipes 65, 76 conduct soap solution and water respectively through bores 122, 120, Fig. 8, into a valve box 112, which has ports 130, 131 communicating with the soap pump 94 and with the water pump 106, and an outlet port 124 communicating with the pipe 37. In the valve box is a sliding block 126 having three channels 127, 128, 129, and during the intake stroke of the pumps the channels 127, 128 connect the soap inlet 122 to the port 130 and the water inlet 120 to the port 131. At the end of the intake stroke, one of the pumps trips a catch, allowing a spring to swing over a lever connected to the valve block 126 so that the latter is shifted into a position (shown in dotted lines in Fig. 8) in which the channel 129 connects the ports 130, 131 to the outlet port 124. Thus the measured quantities of water and soap solution are discharged together. A similar tripping action occurs at the end of the discharge stroke, resetting the valve block for the next intake. Fig. 11 shows an application of the invention to the control of a water-softening plant. The flow of water to and from a container 200 for an ion-exchange material is controlled by a multi-port rotary valve 203, which is actuated by a shaft 208 driven by a motor 210. This motor is normally stationary, but when the base material needs regeneration the valve member is rotated step by step into the various fixed angular positions that correspond to the different stages of the regeneration cycle. The latter is initiated under the control of the photo-electric testing apparatus Z. When the water becomes so hard that a lather is not produced in the testing apparatus, the effect on the photo-electric cell causes a solenoid 254 to be energized. This opens contacts 258, 259 (normally closed), and closes contacts 256, 257, thereby completing a circuit through a constantspeed motor 226 which drives a timing switch comprising an insulating drum 225 having contact segments and coacting with brushes 235 ... 242. In the normal position of the drum (i.e. when the water is soft), the brush 236 is on the insulating portion of the drum just beyond the point C. The brushes are connected as shown so as to effect the successive startings of the motor 210 at the required times by energizing a switch-controlling solenoid 216. The valve shaft 208 operates a circuitbreaker arm 217 which moves over arcuate contacts 219 ... 222, this contact - breaker causing the valve-driving motor 210 to stop, after each successive starting during a regeneration cycle, when the valve member has been moved to a predetermined angular position. Back-flushing occurs when the arm 217 is at rest on the contact 220 ; brine is supplied from a tank 250 when 217 is on 221 (the next starting of the motor 210 in this case occurring when a float-operated switch 251 closes) ; and the rinsing operation occurs when 217 is on 222. During this stage of the regeneration cycle, the timing drum 225 (which, having once been started by the testing apparatus, has rotated continuously up to this point) remains stationary. When, however, a steady condition of softness of the water is again indicated by the presence of lather in the testing apparatus, the contacts 258, 259 are again closed, and the timing drum 225 completes a revolution and stops in its normal position, the valve-motor having meanwhile run until it stops with the arm 217 on the contact 219.