Abstract: A membrane-enclosed amperometric cell (MEAC) for use in determining the concentration of an electroactive species of interest (EASI) in an ambient medium comprises: a working electrode defined by a periphery; a liquid electrolyte covering the sensing area in a film of uniform thickness and being in electrolytic contact with a counter eletrode; a flexible polymer membrane of generally uniform thickness that is substantially impermeable to the electrolyte but permeable to the EASI; the membrane extends in a substantially conforming manner over the sensing area and the electrolyte film thereon; the cell of the invention has a physical permeation barrier that (1) consists of a layer of a substantially inert solid material which is substantially impermeable to the electrolyte and to the EASI; (2) extends between the ambient medium and the sensing area; (3) is disposed in a parallel configuration and in physical contact with the membrane; (4) has at least one opening permitting access of the EASI through the membra

Abstract: A method of thermal protection of a membrane-enclosed amperometric cell of the type comprising an electrolyte within an electrolyte space containing electrodes and enclosed by a semi-permeable membrane which defines a sensor face; heat exchange within said cell is effected for controlled heat compensation of the electrolyte when the sensor face is exposed to temperatures outside of the operative temperature range of the cell.

Abstract: A method of thermal protection of a membrane-enclosed amperometric cell of the type comprising an electrolyte within an electrolyte space containing electrodes and enclosed by a semi-permeable membrane which defines a sensor face; heat exchange within said cell is effected for controlled heat compensation of the electrolyte when the sensor face is exposed to temperatures outside of the operative temperature range of the cell.

Abstract: A method of and a sensor for quantitative electroanalytical determination of elemental hydrogen in a fluid medium are disclosed. A membrane enclosed amperometric cell is used that has at least two electrodes in contact with an aqueous electrolyte to provide a reaction impedance of the cell; the electrolyte is separated from the fluid medium by a membrane that is permeable to elemental hydrogen but substantially impermeable to the electrolyte and provides a membrane impedance of the cell; the electrodes include an anodic hydrogen sensing electrode and a cathodic counter electrode; the sensing electrode has a polished surface consisting of a platinum metal; further, the membrane is selected such that the membrane impedance exceeds the reaction impedance sufficiently to provide for membrane-controlled operation of the cell.

Abstract: A method of thermal protection of a membrane-enclosed amperometric cell of the type comprising an electrolyte within an electrolyte space containing electrodes and enclosed by a semipermeable membrane which defines a sensor face; heat exchange within said cell is effected for controlled heat compensation of the electrolyte when the sensor face is exposed to temperatures outside of the operative temperature range of the cell.

Abstract: A device for mounting and securing a membrane made of a substantially flat piece of flexible polymer film on an amperometric cell that has a substantially cylindrical cell end frontally provided with an electrolyte-bearing sensor face by means of a removable annular holding member; according to the invention the holding member is a substantially non-resilient and creep-resistant die ring, preferably made of stainless steel, having a cylindrical inner surface that fits slidingly onto the cylindrical cell end and at least one tapered inner surface portion that extends outwardly from the cylindrical inner surface toward a leading end of the die ring; the leading end of the die ring is moved over the cylindrical cell end whereby the polymer film is deep-drawn between the die ring and the cylindrical cell end and is permanently shaped to form a cup-shaped membrane portion extending over the electrolyte-bearing sensor face and the adjacent portion of the cylindrical cell end; the resulting cup-shaped membrane porti

Abstract: A method of mounting and securing a membrane of polymer film on an amperometric cell that has a cylindrical cell end provided with an electrolyte-bearing sensor face; the holding member is a substantially non-resilient and creep-resistant die ring, having a cylindrical inner surface that fits onto the cylindrical cell end; at least one tapered inner surface portion extends outwardly toward a leading end of the die ring; the leading end is moved over the cell end whereby the polymer film is deep-drawn between the die ring and the cylindrical cell end and is permanently shaped to form a cup-shaped membrane portion sealingly held by the die ring on the cylindrical cell end during operation of the amperometric cell.

Abstract: A sealed adjusting device for mounting in the wall of a sealed instrument housing that includes at least one adjustable element, such as a potentiometer. The adjusting device comprises an elongated sleeve-like mounting hub capable of being sealingly secured in the housing wall, and a normally freely rotatable or freely turnable knob structured as a hollow capsule rotatably inserted onto one end of the mounting hub. The other end of the mounting hub receives or is connected with a portion of the adjustable element. A spring is provided within the mounting hub to hold the knob in its freely turnable or rotatable position. The knob is operatively connected with a clutch-sleeve for temporary engagement with the rotatable operating end of the adjustable element when the knob is pushed against the spring.

Abstract: Electroanalytic transducers for electrochemical analysis of chemical substances are disclosed. The transducers are of the type which include electrodes contacting an electrolyte solution. In accordance with the method and apparatus of the invention, means insulating an electrode are held in a mutually pressing engagement over preselected portions of the electrode to insulate that portion from the electrolyte and prevent creep of the electrolyte between the insulating means and the preselected portions. Thus, the surface area of the electrode exposed to the electrolyte is maintained substantially constant during the service life of the transducer. In a preferred embodiment, sensor or working and counter electrodes are coaxially mounted and circumferentially coaxially separated by annular insulating means. Spring means urge the inner coaxially mounted electrode and the annular insulating means together so that only the surface of the cross-sectional end of the inner electrode is exposed to electrolyte.