FR2649486A1 - COMPOUND ELECTRODE WITH ION SELECTIVITY OF SAFETY IN CASE OF FAILURE - Google Patents

Abstract

A fail safe ion-selective compound electrode in which a signaling unit provides a signal in the event that the output of the compound electrode is outside a predetermined range and comprising a container 40, a liquid 42 in this container and an element sensitive to ions in this liquid, a control unit 46 which is constituted so as to provide a signal as soon as the output is outside a predetermined range.

Description

COMPOSED ELECTRODE WITH ION SELECTIVITY OF SECURITY IN

BREAKDOWN

  The present invention relates to electrodes

  compounds with ionic selectivity, and more particularly-

  devices capable of detecting and reporting

their own breakdown.

  General purpose pH test compound electrodes are known which operate over the entire pH range and provide an output of approximately minus millivolts (mV) per pH unit, the output at pH 7.0 being zero . It is also known to shift the zero point mV for pH 4.0 or 10.0, so as to avoid

  auto temperature compensation measurement circuits

  matic, by varying the formulation of the internal solution.

  It has been found that a selectively composed electrode

  ionic velocity in which a zero mV output corresponds to ionic concentrations, such as pH, allows outside of a desired range to detect an internal electrode failure. The accompanying drawing shows a preferred embodiment of the invention in schematic view. We will now describe the structure and

  operation of the preferred embodiment of the

  vention generally designated by the reference

digital 10 on the drawing.

  The ion-selective compound electrode 10 has two functional parts, an ion-selective electrode generally designated at 12 and a

  reference electrode generally designated at 14.

  The ion selective electrode 12 comprises a glass rod 16 in communication with an ion selective glass bulb 18. Inside the container defined by the rod 16 and the bulb 18 is the solution 20 in which hangs a silver wire 22 with an ingot of silver chloride attached to it. Internal solution 20 is a pH 0 solution prepared by adding potassium acid phthalate (Merck, AR Primary StandARd), 0.05 mole of phthalate, up to 1.8 mole of potassium chloride, supplementing with deionized water to obtain an amount of one liter and adjusting to its final pH with NaOH. The seal 26 provides a seal around the tubular portion 16

and wire 22.

  The ring 28, which has a liquid connection 30 extending through it, is used to position

  the electrode 12 inside the electrode 14.

  Above the ring 28, the electrode 14 contains a standard reference electrolyte solution 32 of the prior art. The silver wire 34 extends jiisque in the solution 32 and has an ingot of silver chloride 36 attached to it. The annular seal

  38 seals the wire 34 and the two electrodes.

  In the drawing, the container 40 contains a

  solution 42 whose pH is subject to control.

  The wires 22 and 34 are connected to the amplifier 44 which provides a voltage output which reflects the input

  tension of the two wires. The unit shown diagrammatically

  tically and generally at 46 has cir-

  control and alarm circuits and provides a warning signal as soon as the voltage drops to zero; unit 46

  is programmed in such a way that the predefined voltages

  desired endings are in the pH range of 6.5 to 8.2 while voltage O is at pH 5.5. Wall

  exterior 48 provides both the wall for the electro-

  of reference 14 and a zone 50 on which the solution

  tion to be tested can be in contact with the bulb 18 and the link 30 for the heretical electrical contact (by

holes not shown).

  The following table is a comparison of the preferred embodiment according to the invention and the prior art. pH of a solution 40 5.0 6.0 7? 0 8.0 9.0 tested Preferred example safety range) (82) Preferred example -: low pH alarm range:: Preferred example / d range high pH alarm Electrode of art 180 120 60 0 -60 120 anterior / mV output:

Antique art electrode.

  failure point (pH 7.0) Preferred example 90 30 0 -30 -90 -150 210

electrode mV output.

  Preferred example x :: failure point (fold 5t5) :: electrode In normal operation, with the compound electrode 10 in the test liquid 42, the pH is within the safety range set in l 'unit 46, and it is subject to control. If the tube 16 breaks, the voltage drops to zero, which in the embodiment according to the invention is outside the safety operating range or predetermined operating range and a signal circuit in the unit 46 beeps. The signal is then emitted at other voltages outside the range

desired and predetermined.

  Other embodiments in the spirit of

  following claims will appear to the man of

art.

Claims (3)

  1. Ion selectively composed electrode, characterized in that it comprises an ion selective electrode, this electrode comprising: a container (40), a liquid (42) in the container, and an element sensitive to ions in the liquid , a reference electrode (14), and a control unit (46), this unit (46) being constructed to provide a signal as soon as the output from the electrodes is outside of a predetermined range . 2. Compound electrode according to claim 1,   characterized in that the sensitivity relates to the pH.   3. Compound electrode according to claim 2, characterized in that the output is zero voltage, the   zero voltage outside the pre- determined.