With pH measurements in chemical processes, a combined pH/Reference electrode is usually mounted in a by-pass flow fit-ting, a flanged immersion fitting or an on-line retractable fitting. Applications for the PR20 retractable fitting can be found in all processes where the pH sensor should be removed without interrupting its continuity (e.g. pulp slurries, pressurized systems). The Yokogawa design ensures the safe retraction of the electrode from the process without shutting it down.