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.

General Purpose Glass Formulation

The measurement of pH at very high temperatures is detrimental to the sensitive glass bulb and will shorten its 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.

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 HI1332B 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 minimizes 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.

Double Junction Reference

A double junction electrode has an internal compartment surrounding the reference wire. Silver ions are present in the electrolyte of the internal compartment, which houses the Ag/AgCl reference wire; the electrolyte outside this compartment is silver-free. The double junction design means that virtually no silver from the electrode enters the sample. This design allows measurement in applications where silver ions in the sample are undesirable or silver precipitates on the junction are likely to form.

DIN Connector

The HI1217D uses a DIN connector. This type of connector is made only for the HI8314 pH meter. 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.