General Safety Considerations - Vaisala K-PATENTS PR-23 Series Instruction Manual

1 Introduction
The position of the shadow edge is measured digitally using a CCD element (Fig-
ure 1.4) and is converted to a refractive index value n
sensor. This value is then transmitted together with the process temperature via an
interconnecting cable to the Indicating transmitter for further processing, display and
transmission.
V
Figure 1.4 Optical image detection

1.3 General safety considerations

The process medium may be hot or otherwise hazardous. Use shields and protective
clothing adequate for the process medium - do not rely on avoiding contact with the
process medium.
Precautions when removing a standard sensor from the process line :
• Check first that the process line is depressurized. Open a vent valve to the atmos-
phere.
• For a prism wash system, close a hand valve for the wash medium and disable the
wash valve.
• Loosen the flange or the clamp cautiously, be prepared to tighten again.
• Ensure you are clear of any possible spillage and you have a clear emergency es-
cape path.
• After removal of the sensor, it may be necessary to mount a blind cover for security
reasons.
Note: For the Safe-Drive™ system safety rules, see Section 11.5 and for additional
precautions required by explosive atmosphere, see Section 9.10.2.
by a processor inside the
D
a. Optical image
b. CCD element
c. CCD output
3