WARNING The FM unit installations
must comply with the relevant requirements of National Electrical Code (ANSI/NFPA 70) for
Division 2 Hazardous (Classified) Locations and all instructions in this manual. All wiring of
PR‑23‑…‑FM systems must run in a conduit.
Safe sensor wiring
CAUTION Do not modify the unit or use it in ways not described in the documentation. Improper modification or use may lead to safety
hazards, equipment damage, failure to perform according to specification, or decreased equipment lifetime.
CAUTION Do not connect or disconnect
the sensor connector when the circuits are energized. Switch off the power from indicating
transmitter DTR external power switch before disconnecting the sensor cable from the sensor.
After connecting the sensor cable back to the sensor, you can switch power back on.
CAUTION Make sure that the rated
voltage is not exceeded by transient disturbances of more than 119 V.
WARNING The refractometer models
PR‑23‑M, PR‑23‑MS and PR‑23‑W contain parts made of PTFE in sensor heads. These parts are
subject to electrostatic hazard. The refractometer models PR‑23‑M, PR‑23‑MS and PR‑23‑W must
only be used for measuring liquids with high conductivity (> 10000 pS/m) in the presence of
hazardous atmospheres.
WARNING The painted surface of the
enclosure of PR‑23‑MS refractometer is subject to electrostatic hazard. Clean only with a damp
cloth in the presence of hazardous atmospheres.