Calibration of Non-Contact Level Sensors
A single push button is used to set the "Near" (Full) and "Far" (Empty) distances for both ultrasonic and radar sensors. Calibration can be done in the vessel only if the level in the vessel can be varied for both the high and low level, each to be set independently. The sensor can also be calibrated on the bench by aiming the sensor at an appropriate target set at the corresponding distances to the "Empty" and "Full" levels. The target for Ultrasonic Sensors may be water, cardboard, wood or most any flat surfaces, while Radar Sensors require Liquids or a flat Metal surface, including a foil covered surface to properly reflect their signal. Additionaly, sensors can be set by using software programming when connected to a PC (optional hardware required). Factory-calibrated sensors can be provided; consult factory for details and pricing. The 4mA and 20mA set points are independent of each other, fully adjustable over the sensor's range and stored in a non-volatile memory. Calibration feedback is acknowledged via an LED light that turns green, yellow, or red depending on calibration procedures. For radar and long-range ultrasonic applications, it is best to calibrate the far target first and then the near target. Please review the programmable calibration procedure.
Note: Factory-supplied installation manuals are packaged with each sensor, and are also available on the appropriate product documentation tab.
Figure A.Figure B.
A. Far Target Calibration
Setting far target (empty tank) to 4 mA or 20 mA
- Begin calibration mode with the sensor LED color green. Place end of the sensor at the proper distance equal to the far target distance.
- Push button, and hold until LED turns red to set 4 mA [approx. 5 seconds.], or hold until LED turns yellow to set 20 mA [approx. 2 seconds].
- Release button, observe, LED flashes to acknowledge that the "far" target has been set.
B. Near Target Calibration
Set near target (full tank) to 20 mA or 4 mA
- Continue calibration mode with the sensors LED color green. Place the end of the sensor at the proper distance equal to the near target distance.
- Push button, and hold until LED turns yellow to set 20 mA, or hold until LED turns red to set 4 mA.
- Release button, observe, LED flashes to acknowledge that the "near" target has been set.
Note: Both the 4mA and 20mA settings need to be set to different distances. If the Empty is calibrated to 4mA, then the Full must be calibrated to 20mA, or vice versa.
Note: When calibrating radar sensors, liquid or metal targets must be used for proper signal reflection. See reference page for instructions.