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 HI1297D uses general purpose (GP) glass, spherical bulb, titanium body, and cloth junction with gel electrolyte.
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 HI1297D is suitable to use with samples that measure from 0 to 80°C.
The spherical bulb is for general purpose use. Other tip shapes include conic for penetration and flat tip for surface measurements.
A titanium body increases immunity to electrostatic and magnetic fields. It also allows for strong corrosion resistance, even in seawater. Out titanium bodied electrodes’ outer casings also serve as a matching pin. A matching pin is a differential measurement technique used to eliminate ground loops and common mode perturbations for the measurement system. In a system without a matching pin, electrical currents in the samples can affect the reference half cell voltage. The matching pin isolates these current/magnetic fields from the reference electrode for safe, precise pH measurements.
This type of junction is often used on electrodes with gelled electrolytes. The advantage of this junction is it is renewable; as the cloth-like material is pulled out from its position, the junction is renewed with an uncontaminated, fresh surface.
The HI1297D uses a DIN connector. This type of connector is generally proprietary to the meters they are supplied with and may not be interchangeable. Other type of connectors include BNC, screw type, T-type, and 3.5mm to name a few.
ORP Sensing Type Platinum Measurement Range pH: 0 to 13, ORP Reference Cell Type single, Ag/AgCl Junction Type/Flow Rate cloth Type of Electrolyte gel Body Material titanium Tip / Shape pH: conic (3mm); ORP: platinum sensor Matching Pin yes Max. Pressure 3.0 bar Temperature Operating Range 0 to 80°C (32 to 176°F) - GP Body Length/Overall Length 105 mm / 145.5 mm Temperature Sensor yes Outer Diameter 14 mm Cable 7-pole; 1 m (3.3') Connector Type DIN Amplifier yes Recommended Use municipal water, swimming pools, wastewater, water treatment