The refractometer sensor is installed in the process, either directly by welding a mounting flange to 2 in or larger pipes or vessels, or using a 1 in, 2 in or 3 in cross flow cell. Due to the sensor’s rugged, innovative non-weld sensor body, and self‑cleaning or optional wash system capabilities, the PR‑23‑RP functions accurately and reliably in harsh refinery conditions. Intrinsically safe and hazardous area certification is provided for hazardous areas.