Signet offers three classes of pH sensors 2717/2754, 2764, 2774. Each class of sensors has specific design enhancements that allow the sensors to be installed into different applications. The 2754/2717 series are considered a general purpose sensor; these sensors are designed for general water treatment processes that have no harsh chemicals or heavy metals. Chemicals and process with heavy metals can attack and destroy (poision) a general purpose sensor very quickly. Below is a pH sensor selection chart that will help you select the proper pH sensor for a specific application. This chart should be used as a guideline only. Contact GF technical support if the chart does not include your application.