Hanna Instruments

Scientific Equipment

HI-1291D pH Electrode PEI body, single junction with Temp °C sensor

HI-1291D pH Electrode PEI body, single junction with Temp °C sensor

Hanna HI-1291D pH Electrode PEI body, single junction with Temp °C sensor

HI-1291D pH Electrode PEI body, single junction with Temp °C sensor

In Stock
£179.35 (exc. VAT) £215.22 (inc. VAT)

The HI-1291D is a PEI body, single ceramic junction pH electrode with a DIN connector. Can be used with the HI-208 pH meter.

This design consideration is ideal for general laboratory use.

  • No need to refill electrolyte
  • Made for use use with the HI-208 pH meter
  • Great for general purpose laboratory and education use
  • Din Connection

    HI-1291D pH Electrode PEI body, single junction with Temp °C sensor information

    Hanna's extended description

    Hanna Instruments offers a wide variety of pH electrodes that are designed for many different applications. The type of glass used for sensing pH, bulb shape, body material, type of junction, type of reference and electrolyte used are just some of the design considerations.

    The HI-1291D uses general purpose (GP) glass, spherical bulb, polyetherimide (PEI) body, single ceramic frit, and double junction.

    General Purpose Glass Formulation

    The measurement of pH at very high temperatures is detrimental to the sensitive glass bulb and will shorten the life of it. A pH electrode with general purpose (GP) glass will have a resistance of 100 megaohms at 25°C while the resistance of LT glass is around 50 megaohms at 25°C. As the temperature of the glass decreases in the sample, the resistance of the LT glass will approach that of GP glass. If using GP glass, the resistance would increase above the optimum range, resulting in increased impedance and ultimately affecting the measurement. The HI-1291D is suitable to use with samples that measure from 0 to 70°C.

    Spherical Bulb

    The spherical bulb is for general purpose use. Other tip shapes include conic for penetration and flat tip for surface measurements.

    PEI Body

    The body of the HI-1291D is composed of polyetherimide (PEI) resin. The PEI body is suitable for a wide range of applications and excels in field measurements due to its durability. The shielding around the spherical glass tip minimises breakage due to accidental bumping or dropping of the electrode. The PEI plastic is a high quality plastic that is chemically resistant to many aggressive chemicals.

    DIN Connector

    The HI-1291D uses a DIN connector. Other types of connectors include BNC, screw type, T-type, and 3.5mm to name a few. These types of connectors tend to be proprietary for a particular type of meter and are not interchangeable.

    Electrodes explained

    Conventional electrodes are normally single junction. These electrodes have only a single junction between the internal reference wire and the external solution. Under adverse conditions, such as high pressure, high temperature, highly acidic or alkaline solutions, the positive flow of the electrolyte through the junction is often reversed resulting in the ingress of sample solution into the reference compartment. If this is left unchecked, the reference electrode can become contaminated, leading to complete electrode failure. Another potential problem with single junction electrodes is the clogging of the junction due to silver chloride (AgCl) precipitation. Silver can be easily precipitate in samples that contain Tris buffer or heavy metals. When the electrolyte solution makes contact with the sample, some AgCl will precipitate on the external face of the junction. The result is drifty readings obtained from the sensor.

    Hanna’s double junction system, as the name implies, has two junctions, only one of which is in contact with the sample as shown in the figure. Under adverse conditions, the same tendency of sample ingress is evident. However, as the reference electrode system is separated physically from the intermediate electrolyte area, the contamination of the electrode is minimised. The likelihood of clogging of the junction is also reduced with a double junction electrode since the outer reference cell uses a fill solution that is “silver-free”. Since there is no silver present, there is no precipitate that can form to clog the junction.


    Specifications list


    Description pH electrode
    Measurement Range pH: 0 to 13
    Junction Type/Flow Rate ceramic, single
    Type of Electrolyte gel
    Body Material PEI
    Tip / Shape Spherical (dia: 5.0 mm)
    Max. Pressure 2 bar
    Temperature Operating Range 0 to 70°C - GP
    Temperature Sensor yes
    Cable coaxial; 1 m
    Connector Type DIN
    Amplifier Yes
    Recommended Use general purpose

    Product Literature

    literature - PDF

    Hanna Instruments Literature

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