The Walchem pH electrode and ORP electrode are designed to function where other electrodes cannot.
In room temperature water, they can handle up to 500 psi. In low-pressure installations, they can handle up to 275°F (135°C) without melting.
In all cases, pH/ORP electrode life will be maximized by operating at room temperature, and the expected life span at temperatures above 140°F (60°C) will be short. But if low temperature operation is impossible, these electrodes will fit the bill.