Campbell Scientific AL200 ALERT2 Encoder, Modulator, and Sensor Interface - Manual (Page 42)

Appendix H. Calculating Multipliers and Offsets
Now, we can calculate pressure based on the reading we get from the sensor.
For example, you measure the sensor’s output as 2543.210 mV. Pressure
would be determined by:
Pressure = (0.0060 • 2543.210) + (–0.074) = 15.263 psi
To determine water depth, simply multiply the pressure value by the
appropriate conversion factor.
For fresh water this is:
1 psi = 2.308 ft.
For salt water this is:
1 psi = 2.250 ft.
For the above example (assuming fresh water):
Depth of Water = Pressure • 2.308
Depth of Water = 15.263 • 2.308 = 35.226 ft.
These calculations can easily be performed using many spreadsheet programs
by plotting the sensor’s measurement range versus the sensor’s output range.
The equation of the trendline contains the multiplier and offset.
H-2