Water Quality Sensors

Hanna Combination Double Junction AmpHel pH and ORP Electrodes

Hanna's latest additions to their range of combination pH and ORP electrodes incorporate over 20 years of electrode manufacturing experience. These advanced electrodes feature a combination Ag/AgCl sensor & reference system, and proven flat tip technology for superior field and in-line performance. Hanna's flat tip electrodes have shown significantly less breakage than bulbous electrodes. Flat electrodes also experience less abrasion in a flow application and nearly eliminate deposits.

Hanna's glass sensors are thicker and the composition has been formulated to offer greater chemical resistance and an increased impedance range. For those applications that have proven particularly hostile to glass sensors, Hanna has developed four types of specialized glass. First is an extremely durable sensor glass for general purpose use. This glass can withstand sudden impacts and extreme mechanical stress. The remaining types of electrode glass allow continuous monitoring in highly acidic solutions containing fluoride ions, as well as high or low temperature process streams. Aggressive chemicals and high temperature are common aggressors of pH and ORP probes, therefore the sensor body is constructed with Kynar (PVDF), and Hanna's electrodes have been constructed to operate reliably in pressurized systems up to 87 psi (6 BAR).

One of the most common causes of electrode failure is fouling of the junction. The junction simply becomes physically clogged due to either solids in the sample solution or by precipitation (of AgCl for instance). To help overcome this problem Hanna has increased the physical size of the junction with the result of increasing the life of the electrode when introduced into applications that would normally quickly clog the junction. Also with a double junction system the reference electrode is not in direct contact with the sample and the problem of reference poisoning is nearly eliminated.

With Hanna's AmpHel electrodes there is an amplifier built into the electrode and problems associated with high impedance are now isolated to one location. The high impedance circuitry is located at the top of the electrode which is completely encapsulated. As a result you now have low output impedance signals from the electrode to the data logger. This means you can use ordinary connections with long unshielded cables (up to 50 meters). Also these electrodes have been engineered with a replaceable battery (1 to 2 year life) to power the amplifier. This feature adds life to the electrode and aids in troubleshooting. Specifications