FC100B – pH Elektrode

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 FC100B uses general purpose (GP) glass, spherical bulb, food grade PVDF body, single ceramic frit, double junction and is refillable with 3.5M KCl. General Purpose Glass Formulation General Purpose (GP) glass, as the name implies, is a standard glass formulation that is used for general use. A pH electrode with GP glass will have a resistance of 100 megaohms at 25°C and is suited for measuring pH of samples that are at ambient temperatures. The FC100B is suitable to use with samples that measure from 0 to 80°C. Spherical Bulb The spherical bulb is for general purpose use within the food industry. Measurements can be made in liquids or slurries that allow easy measurement of solid and semi-solid food products. Other tip shapes include conic for penetration and flat tip for surface measurements. PVDF Body Polyvinylidene fluoride (PVDF) is a food grade plastic that is resistant to most chemicals and solvents, including sodium hypochlorite. It has high abrasion resistance, mechanical strength and resistance to ultraviolet and nuclear radiation. PVDF is also resistant to fungal growth. Single Ceramic Double Junction Reference The FC100B is a double junction design. pH electrodes are available as single junction or double junction. See below for a complete description of the differences. The junction 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 ?L/hour. Other junction types are available with higher flow rates and made with different materials. Refillable The FC100B is a refillable probe. 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 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 FC100B 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 type 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. Single Junction Versus Double Junction pH Electrodes Single junction electrodes use a fill solution as the HI7071 that contains 3.5M KCl, while double junction electrodes typically use HI7082 that contains 3.5M KCl.