Pentair HAFFMANS GMT - Calibration; Determining Pressure Gauge Accuracy

HAFFMANSGMT
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GMT Page 17 of 37
6. CALIBRATION
6.1 Determining the accuracy of the pressure gauge
The CO
2
Gehaltemeter’s pressure gauge is accurate to 1% of its total scale. The pressure
gauge can be calibrated using a Haffmans Gauge Calibration Device (GCD).
Method:
Attention! The pressure gauge is calibrated for the most common pressures,
i.e. 1 bar and 2 bar.
1. Unscrew the pressure gauge’s cover (pos. 67),
2. Using a pressure gauge puller (included in the service set), pull the pressure gauge out
of the instrument whilst rotating it,
3. Connect the pressure gauge to the appropriate connection on the GCD (screw; output at
the front),
4. Connect an external gas supply to the GCD,
5. Set the GCD to an exact pressure of 2 bar and compare this to the reading given by the
pressure gauge.
If the pressure gauge does not give the correct reading, the pressure gauge’s needle must be
reset.
Method for 1 bar:
1. Unscrew the screws on the side of the pressure gauge and remove the chrome cap,
2. Remove the plastic sight-glass,
3. Remove the needle using the needle puller (included in the service set),
4. Set the pressure of the GCD to exactly 1 bar,
5. Position the pressure gauge’s needle to 1 bar and push it into place,
6. Check the linearity by setting the pressure of the GCD to half of the calibration pressure
(0.5 bar),
7. Read the pressure given by the pressure gauge (the value must be 0.5 bar +/- 1%),
8. Refit all the components into their original positions.