Abstract: A free chlorine analyzer including a probe immersible in chlorinated water having oxygen dissolved therein, the analyzer being adapted to continuously and accurately measure the concentration of free chlorine in the water without regard to its oxygen content. The probe includes a noble metal measuring electrode, an oxidizable metal counter electrode and an electrolyte which in combination with the electrodes defines an electrochemical cell whose output current depends on the amount of the chlorine passing into the cell through a diffusion membrane permeable to this gas. The cell is connected through one or more serially-connected diodes operating in the forward direction to an output resistor across which is produced a voltage that depends on chlorine concentration. The voltage drop across the diodes impresses a potential on the cell which causes it to operate in a current limiting range and renders it insensitive to the oxygen content of the chlorinated water.

Abstract: A probe immersible in process water or wastewater having oxygen, chlorine or another gas dissolved therein and adapted to continuously and accurately measure the concentration of the gas. The probe includes a noble metal measuring electrode, an oxidizable metal counter-electrode and an electrolyte which in combination with the electrodes defines an electro-chemical cell whose output current depends on the amount of the gas passing into the cell through a diffusion membrane permeable to the gas being analyzed. In order to simulate the effect of rapid sample flow past the membrane and thereby maintain the analytical sensitivity of the instrument, the probe is vertically supported through a flexible coupling and includes an internal motor having an unbalanced rotor secured to its shaft. Rotation of the rotor causes the probe to nutate about its vertical axis to simulate the effect of a rapid sample flow.

Abstract: A technique for continuously indicating the concentration of ozone dissolved in water, use being made of an amperometric cell, preferably formed of a gold cathode concentrically disposed within a tubular copper anode to define an annular passage, the cathode being rotated at high speed. A sample stream of the water is directed through the passage at a predetermined flow rate whereby in the absence of dissolved ozone, the cathode is polarized, but in the presence thereof, depolarization takes place to cause a current to flow in the cell, the current being measured to provide a reliable and continuous reading of ozone concentration.