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8. IN SITU CALIBRATION
A valuable feature of the Model 4650 settlement system is the ability to perform in situ
calibrations. This is done by connecting an auxiliary reservoir to one of the fluid lines as shown
Figure 8 - In Situ Calibration Apparatus
First close off the valve at the bottom of the reservoir, half-fill the auxiliary reservoir with the
same liquid used in the reservoir and connect it via a short length of tubing to one of the fluid
lines, being careful not to introduce air into the lines. Cap off the open fitting on the reservoir
connection and disconnect the vent line from the vent manifold. Raise and lower the auxiliary
reservoir by measured amounts using a scale to measure the elevation of the water level.
Read the sensor using a GK-403, GK-404, or GK-405 readout box. (See Section 3 for readout
instructions.) Record the readings after allowing sufficient time for the readings to stabilize
(usually requires around one to five minutes although it will be noted that the sensor responds
instantaneously to change of water elevation even where the liquid tubes are very long.) Record
the sensor readings at five or more different elevations, then, from the data calculate the
calibration factor and compare it with the factory generated value on the calibration report.
Remove the auxiliary reservoir and reconnect the fluid line to the base of the reservoir and the
vent line to the desiccant chamber or vent line manifold. Reopen the valve at the base of the
reservoir.
