Hanna Instruments offers a wide variety of pH electrodes that are designed for many different applications. The type of glass used, body material, type of junction, type of reference and electrolyte used are just some of the design considerations.
The HI5311 uses a glass body, single ceramic junction and is refillable with 3.5M KCl.
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 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 HI5414 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 HI5414 is a refillable probe via the special side arm construction. Because of this special recharge system, it is possible to connect an outside container that will increase the amount of electrolyte of the reference half cell and thus, the pressure inside the electrode. By so doing, the junction has the ability to work in high pressure environments without the danger of implosion. Since it is a single junction calomel reference electrode the fill solution is the HI7082 3.5M KCl. This solution does not contain any silver as with single junction silver/silver chloride reference electrodes. 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.
4 mm Connector
The HI5414 uses a 4 mm banana connector. This type of connector is easily plugged into the reference input on suitable meters. Other type of connectors include BNC, 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.