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 HI1611D uses high temperature (HT) glass, spherical bulb, glass body, single ceramic junction and gel electrolyte.
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℃ while the resistance of HT glass is around 400 megaohms at 25℃. As the HI1611D is used at elevated temperatures the resistance decreases to approach the that of GP glass. The HI1611D is suitable to use with samples that measure from 0 to 80℃.
The spherical bulb is for general purpose use. Other tip shapes include conic for penetration and flat tip for surface measurements.
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.
Single Ceramic Junction
The outer junction of an electrode, also known as a salt bridge, is necessary component of the electrical circuit. The movement of ions must flow through the junction for a steady reading. The outer reference has a single ceramic frit. The ceramic is a porous material that is easily fused with the glass body and has a similar expansion coefficient. A single ceramic junction has a flow rate of 15-20 μL/hour. Other junction types are available with higher flow rates and made with different materials.
The HI1611D uses a DIN connector. This type of connector is generally proprietary to the meters they are supplied with and may not be interchangeable. The HI1611D is recommended for use with Hanna’s HI8314 pH meter. Other type of connectors include BNC, screw type, T-type, and 3.5mm to name a few.