Pentair HAFFMANS c-DGM, Instruction Manual

Page: 43 / 79

HAFFMANS c-DGM/i-DGM
c-DGM/i-DGM Page 43 of 78
7. Calibration and compensation
7.1 Calibration of the temperature sensor
The temperature sensor is an accurate PT-100 that is associated with tight tolerances and
therefore does not require calibration.
A check can be performed by initiating a flow of liquid through the measurement chamber and
comparing the temperature displayed on the DGM with a reading from a precision thermometer
placed in the outlet of the DGM.
7.2 Calibration of the pressure
The pressure in the CO
2
formula is an absolute pressure. The pressure sensor measures
absolute pressure. This results in automatic compensation for changes in atmospheric pressure
caused by variable weather conditions or altitude differences.
We suggest that the pressure sensor be checked/calibrated once per month. Select the
“Configuration” menu and the “Calibration” submenu to perform the calibration.
Procedure:
1. Remove the liquid from the measurement chamber.
2. Make sure the handle is depressed (measurement position).
3. Remove the screw (pos. 03) from the measurement chamber and replace it with the
calibration screw from the service set.
Warning
Tighten the calibration screw carefully so it does not damage
the threads in the plexiglass.
4. Connect the DGM to a calibration device (for example the Haffmans Gauge Calibration
Device) and a source of pressurized calibration gas (for example air or CO
2
).
Warning
To prevent damage to the screw threads in the plexiglass, do
not subject the calibration screw to any force from the side.
5. Now follow the instructions on the following 2 pages: