Offset calculation

The pressure created is directly proportional to the water column above the sensor. An offset is used to correct the final measurement to any error due to sensor zero offset or installation. The steps for calculating the offset:

  1. Use a staff gage (or other device) to measure the initial elevation of water.

  2. Measure the water pressure using the CS451/CS456.

  3. Convert the pressure measurement to water level.

  4. Subtract the CS451 level measurement from the initial elevation measurement.

For example, if the correct elevation of the water, as measured by a staff gage or other measurement device, is 20 feet, and the CS451 provides a reading of 5.76 psig, then:

5.76 psig • 2.31 ft/psig = 13.3056 ft.

So, the offset is the following:

20 ft – 13.3056 ft = 6.6944 ft

Include an expression in the CRBasic program to account for this offset.