Patent GB-782352-A (GB)
Title: Improvements in or relating to apparatus for detecting a change in a property of a liquid
IPC: G01N1/10
Filed: 1953-01-26
Abstract: 782,352. Photo-electric control of water. NECKAR WATER SOFTENER CO., Ltd., and NORRIS, H. E. May 13, 1954 [Jan. 26, 1953], No. 2269/53. Class 40 (3). Apparatus for the detection of a predetermined change in a property of a liquid, such as the attainment of a particular hardness in water, comprises a timing device which periodically. allows a sample of the liquid to flow to equipment which includes means responsive to the change, this means being energized under the control of the timing device after the sample has been supplied to the equipment to ascertain whether the change has taken place. The means responsive to the change may comprise a photo-electric cell which detects when the height of lather formed by mixing the liquid with soap solution is too low or three probes, one of which projects into the water, the other of which contacts the liquid level and the other the lather level. General arrangement and operation.-A valve 3 driven by motor 4 may admit water at will to a sampling tube 1 in which is a probe 16 which makes contact with the water when its level is sufficiently high. A three-position valve 10 driven by a motor 7 may either admit soap solution to a measure 9 or may allow it to flow to the sample tube. Motor 7 also drives a valve 6 to drain the sample tube. Situated on opposite sides of the sample tube are a light source in a housing 12 and a photo-electric cell in a housing 13. In operation soap solution is admitted to the sample tube under the control of a timing switch. Water is then admitted, its velocity being adequate to ensure mixing. The mixture is then tested by the photo-electric arrangement and if the lather is not sufficiently high, warning devices are operated and the apparatus stops. If the lather is high enough the sample tube is drained and the apparatus restarted. The cycle is repeated at intervals depending on the timing switch until the prescribed hardness is obtained when it stops. Detailed operation, Fig: 1 (Comp.).-Contacts Y, W, X and T, S are cam-operated by motors 4 and 7 respectively, contacts K, N, M, R, Q, V, P, U and L by the second of two timing switches 22, 24. At the beginning of a cycle contacts X, T and K and valve 3 are open, valve 6 shut and valve 10 allows soap solution to flow from the tank 8 to the measure 9. When the water meter registers that a certain quantity of water has flowed through the softener it closes contacts 26, energizing relay H, lighting pilot lamp 23 and starting time switch 22. A mercury switch e in the time switch closes and starts second time switch 24. Contact V closes and motor 4 runs to open valve 3 which admits water to the sampling tube. After a quarter revolution the motor opens contact Y and stops itself. The water flows to drain since valve 6 is open, thus flushing the sample tube. Meanwhile, contact X closes and V opens. Subsequently P closes energizing relay O which locks over a contact in series with W. Relay O connects probe 16 via relay Z to a positive potential. Mercury switch e now opens and contact R closes. Motor 7 runs, closing T. Motor 7 closes valve 6 so that the sampling tube starts to fill and turns valve 10 through a quarter revolution so that soap solution and water enter the tube together. R then opens. When the water level in the sample tube reaches probe 16 relay Z is energized, motor 4 runs, closing valve 3 and closing Y, and after a quarter revolution opens contacts W and X and stops itself. Relays O and Z de-energize in turn. Time switch 22 now closes its contacts # while M also closes. Relay G energizes and locks via a holding contact and N. Relay G energizes amplifier 25 which in turn energizes D and in turn F which locks. M opens. A three-minute period is then allowed for the lather to settle, when L closes, energizing relays E and I and light source 12. If the water is so hard that light from source 12 is able to reach cell 14 a momentary drop in the amplifier output is produced and the contact of relay D falls back to the position shown, energizing relays A and J which lock and operate bell 27 at line 28. L is then opened by time switch 24 de-energizing relay F and I and switching off light 12. After a short interval N opens, de-energizing relay G and cutting off amplifier 25. Relays F and A deenergize and bell 27 ceases ringing. Relay D de-energizes and N closes. On hearing the Warning the operator commences re-generation and resets the water meter, opening contacts 26. Relays H and J de-energize and the pilot light and warning lamp switch off. After contact W opened, Q closed, starting motor 7, closing S. Valve 6 opens and after a quarter revolution the motor stops itself over contact T. Q then opens. Sampling tube 1 empties. Contact U then closes and motor 4 runs, closing X and W. Valve 3 opens and after a quarter revolution the motor stops itself at contact Y. Water then flushes out the sampling tube. R then closes, restarting motor 7, closing valve 6 and T. Water then overfills the sample tube, flowing to drain through an auxiliary tank 17. After a quarter revolution the motor stops itself at S. Time switch 24 then opens R and closes V, thus starting motor 4. The motor closes Y and after a quarter revolution stops itself at X. Valve 6 is now opened so that the sample tube is drained. Valve 10 has rotated a quarter revolution to fill the measure 9 with soap solution. After contact K has been opened time switch 24 stops since mercury switch e is open. Later mercury switch f opens and time switch 22 stops because relay H and J were de-energized by the resetting of the water meter. If the hardness is within permitted limits lather will be present when light 12 is switched on, hence the cell receives no light and when L is opened by time switch 24 relays E and I de-energize and light 12 goes out. Subsequently W is opened, de-energizing locked relay G and cutting out amplifier 25. Relay D de-energizes, then W is closed. After a few seconds Q closes. Motor 7 runs, closes S, and stops itself after a quarter revolution, over T. Valve 6 opens and the sampling tube empties. Valve 10 is advanced 90 degrees. Later V closes and motor 4 runs, closing X and W and opening valve 3 and then stopping itself at Y. Water now flows through the tube to drain. Meanwhile V is open. Later R closes and motor 7 runs, closing T and valve 6 and advancing valve 10 by 90 degrees. Water overflows the sampling tube. After a quarter revolution the motor stops itself at S. R then opens, later V is closed and motor 4 runs, closing Y and, after a quarter revolution, opening X to stop itself. Valve 3 is now closed. V is opened and Q is closed so that motor 7 closes S, opens T and Q and stops. Valve 6 is now open so as to drain the sampling tube and measure 9 is filled from tank 8. When K opens, time switch 24 stops, since mercury switch e is open. A little later f opens but switch 22 does not stop since H is energized and the cycle is repeated.