Refillable pH Electrode with Side Arm Construction and BNC Connector HI1135B

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 HI1135B uses high temperature (HT) glass, spherical bulb, glass body, double ceramic frit, double junction and is refillable through the side arm construction with 3.5M KCl.

High-Temperature 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 HT glass is around 400 megaohms at 25°C. As the HI1135B is used at elevated temperatures the resistance decreases to approach that of GP glass. The HI1135B is suitable to use with samples that measure from 0 to 100°C.

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

Glass Body
The glass body is ideal for laboratory use. The glass is resistant to many harsh chemicals and is easily cleaned. The glass body also allows for a fast transfer of heat to the internal reference electrolyte. The mV generated by the reference cell is temperature dependent. The faster the electrode reaches equilibrium, the steadier the reference potential.

Double Ceramic Junction
The double ceramic junction allows a faster flow rate of electrolyte from the reference into the solution. A standard pH electrode will use a single ceramic junction that allows for 15 to 20 µL/hour of electrolyte to flow; the HI1135B has two ceramic junctions, providing for 30 to 40 µL/hour of electrolyte to flow. This higher flow rate provides faster electrode response and more stable measurement in viscous solutions or samples of low conductivity, such as pure water, where a long stabilization time is often observed.

Side Arm Construction
The HI1135B is a refillable probe via the special sidearm construction. The side arm allows for continuous filling of the electrolyte solution in applications that require constant monitoring. Since it is a double junction pH electrode the fill solution is the HI7082 3.5M KCl. This solution does not contain any silver as with a single junction electrode. The absence of silver will prevent any silver precipitate from forming at the junction surface and clogging it. Clogging of the junction will result in drifty and erratic readings.

BNC Connector
The HI1135B uses a BNC connector. This type of connector is universal in that it can be used on any pH meter that has the female BNC probe input. Other types of connectors include DIN, 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.