Electrode Datasheets | Installation

  • Silver Chloride LD135 Electrode Datasheet

    Note: you can also download a pdf file of the data sheet for the LD135.

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    General Description

    The LD135 is a long life silver/silver chloride reference electrode with a stable reference potential specifically for permanent installation. The essential components are silver metal, silver chloride, soluble silver ions and chloride ions.

    Ag, AgC1(s), C1-, Ag+

    A sparingly soluble salt, silver chloride, is in equilibrium with a saturated solution of this salt which precipitates in the course of electrolysis. The reversible electrode reaction consists of silver ions going into solution and then combining with the chloride ions to form silver chloride. Thus its potential is determined by the following reactions:

    Ag ↔ Ag+ e-

    Ag+ + Cl- ↔ AgC1(s)

    Ag+ C1- ↔ AgC1(s) + e-

    The potential is dependent on temperature and the concentration of chloride ions in accordance with the following equation:

    E=E0- RT   1n[C1-]
    F

    Where E0, R, F and T are the standard potential, gas constant, Faraday Constant and temperature respectively. The reaction has been proved to obey these equations in solutions with pH’s of between 0 and 13.5. The potential is however very sensitive to traces of bromide ions which make it more negative.

    The electrode element has been prepared by electrolytic precipitation of silver chloride onto silver metal. This has then been embedded in a gel containing a known concentration of chloride ions and an anti-drying agent. The housing consists of a white nylon barrel, white nylon inserts, cable gland rated at IP68 and porous ceramic junctions separating the mortar from the external environment at the measuring interfaces.

    Specification

    Element Type:

    Ag, AgCI(s), CI-, Ag+
    Typical 3g silver per electrode

    Potential:

    -15Mv +/-10Mv versus the Saturated Calomel Electrode (SCE)
    230Mv +/-10mV versus the Standard Hydrogen Electrode (SHE)

    Drift:

    less 3mV in 24 hours.
    Typically less than +/-10mV expected in 20 years

    Note: The potential drift is subject to temperature. Donnan potential and
    liquid junction potential changes within the surrounding environment
    which may mask any changes produced by the electrode itself.

    Internal Resistance:

    Less than 2kOhms

    Polarisation Characteristics (determined galvanostatically in calcium hydroxide solution)

    2mV potential shift after the application of 0.1mA for 30 seconds.
    12mV potential shift after the application of 1mA for 30 seconds.

    Dimensions:

    135mm long x 26mm diameter
    Cable gland 20mm long x 15mm diameter

    Housing:

    White Nylon Barrel
    White Nylon Insert
    Cable Gland to IP68
    Ceramic junction measuring interfaces: End sensor 1 x 19mm diameter
    Circumferential 3 x 7mm diameter.

    Cable:

    Supplied to order

    Expected life:

    More than 57 years at a leakage current of 1mA will result in the loss of 2 grams of silver. The functional life of the electrode will most likely to be determined by the life of the associated cables.

    Other Features:

    Large Measuring Interface (400mm2 )
    Anti Drying agent

     

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Did you know?

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