Industrial Instruments INC

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CONDUCTIVITY CELL PROBLEMS? why not measure conductivity with an electrodeless system? wm

heatstone bridge-type instruments and conven­ W tional electrode-type cells, originally designed for laboratory measurements of solution conductivity, have been extensively modified over the course of the past few decades and successfully applied to a great many industrial control problems. However, in cer­ tain application areas, such as solutions containing abrasive or fibrous solids and very conductive or highly corrosive solutions, the problems of servicing the conductivity cell and maintaining the electrodes in good working condition is severe enough to limit the use of the method. The Type RS electrodeless con­ ductivity measuring system, first developed by Indus­ trial Instruments Inc., in 1957, eliminates the necessity for liquid contacting electrodes and has extended the applicability of the conductivity method to many sys­ tems which were heretofore considered problem areas. These include the following: Black Liquor Hydrofluoric Acid Molten Ammonium Nitrate 10r/r Sodium Hydroxide Slurry of Bauxite and NaOH 98% Sulfuric Acid Sea Water Nitric Acid and Uranyl Nitrate Sulfuric Acid and Copper Sulfate Cement Slurry Industrial Sewage Hydrochloric Acid and Aluminum Magnesium Bisulfite Drilling Mud

In its essence, the RS electrodeless conductivity sys­ tem (U.S. Patent 2,542,057) measures the resistance of a closed loop of solution by the extent to which the loop couples two transformer coils. The liquid to be measured is contained in a closed loop. Nonmagnetic and nonconductive piping must be used for this loop and two single winding toroidal coils are mounted on the piping. One is connected to a transmitter which supplies a voltage in the high audio-frequency range. The output of the transmitter must be stable and free from drift in both frequency and amplitude. The second toroidal coil is connected to a receiver which measures the output voltage from this winding. The equivalent electrical circuit consists of two trans­ formers. The first has as its primary winding, the input toroid and, as its secondary, the closed loop of solution. The second transformer has, as its primary, the closed solution loop and, as its secondary, the out­ put toroid. With constant input voltage, the output of this system is proportional to the conductivity of the solution. The receiver is a high impedance input, highly degenerated vacuum tube voltmeter. The out­ put from the amplifier is rectified in a conventional bridge-type meter rectifier and displayed directly on a large indicating meter. By placing a small resistor in series with the meter, a millivolt signal is provided for feeding a remote potentiometer recorder when desired. High and low alarm and other control fea­ tures may be incorporated as desired. If you have a difficult or questionable solution con­ ductivity application, and you think that eliminating the electrodes would relieve the problem, write us in detail.

INPUT TOROID

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SOLUTION LOOP

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TRANSMITTING 8 RECEIVING UNIT

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Chloride

Schematic diagram shows the basic electrodeless system.

Electrolytic

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ANALYTICAL CHEMISTRY

411

Conductivity

Drawing indicates unique conductivity cell design.

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Industrial Instruments INC. 2 0 1 CEnter 9-6200

TWX: 2 0 1 239-4704

Circle No. 64 on Readers' Service Card 100 A

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89 Commerce Road, Cedar Grove, Essex County, N. J.

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OUTPUT TOROID