American Magnetics 286 Multi-Sensor Liquid Level Instrument (CE-Marked) - Manual (Page 40)

26
Calibration
Approximate calibration
3.2.3 Approximate Calibration
This procedure is the least accurate form of calibration and should be used
only when the aforementioned calibration procedures are not possible. The
approximate calibration method can be used in cases where the sensor
cannot be dipped into the target liquid, the full active length of the sensor
cannot be dipped into an open dewar, or both. Approximate calibration
may also be useful for situations where the sensor cannot be dipped into
the target liquid under the expected operating pressure.
If the target liquid is not available for dipping, a substitute non-conducting
reference liquid can be used. If the full length of the sensor cannot be
dipped, then a partial length dip can be performed. If both situations are
encountered, then a partial length dip can be performed in a substitute
reference liquid.
1. Enter the calibration menu by using the passcode, and select the
appropriate sensor input to calibrate as documented in paragraph
3.3.2 on page 30.
2. Choose the Perform option and select the desired calibration to
perform as documented in paragraph 3.3.5.1 on page 33.
3. Enter the appropriate active length value as documented in
paragraph 3.3.5.2 on page 33.
4. Place the instrument in the MIN/MAX entry screen as documented
in paragraph 3.3.5.3 on page 34.
5. First, cool the sensor as much as possible by dipping the sensor as
far as possible in the available reference liquid.
6. Slowly withdraw the sensor out of the reference liquid until the
level is approximately even with the bottom hole in the sensor and
then press the MIN button as prompted by the display. When the
calibration point has been accepted, the display will change to
Entered and the Model 286 will beep once. The location of the
liquid level on the sensor when the MIN button is pressed becomes
the 0% level.
Note
Having a small amount of liquid in contact with the sensor at the
MIN calibration level helps stabilize the sensor capacitance for 0%
level indication.
7. Reinsert the sensor in the reference liquid as far as possible, but
not exceeding 1" below the top hole. Note the physical location of
the liquid level on the sensor at the maximum insertion depth.