HACH LANGE ORBISPHERE 3654, Руководство пользователя, Страница: 35 / 58

33
Section 6 Calibrations
6.1 Barometric pressure sensor calibration
You must have access to an accurate barometer to calibrate the instrument's internal barometric
pressure sensor. This is done using the PC WIN3654 program.
The calibration procedure then displays a
Pressure Calibration
dialog box (as illustrated in
Figure 9 ). The
Measured Pressure
value shows the current instrument pressure reading.
Enter the current atmospheric pressure, in mbars, in the
Calibration Pressure
entry box.
Choose
Calibrate
to direct the instrument to read and display the
Measured Pressure
using
this calibration value.
Choose
Quit
when you are satisfied with the pressure calibration to return to normal operation.
6.2 Sensor calibration
The TC sensor can be calibrated in pure H
2
or N
2
gas at atmospheric or elevated pressure. The
following table gives information regarding the different methods.
Before calibrating check that the sensor membrane surface is tight, smooth and wrinkle free.
Select the gas measurement phase for calibration (for full details see
Gas measurement phase
on page 29 ). Next, select the calibration medium using the WIN3654 program (see Calibration
medium on page 31 ).
Choose
Troubleshooting
,
Pressure
Calibration
and a message will warn that the
current calibration will be lost.
Choose
OK
to continue.
Figure 9 Pressure calibration screens 2 & 3
Table 4 Sensor calibration information
Calibration Method Time Benefits Drawbacks Reference
Gas at atmospheric
pressure
5 min Quick and easy
Less accurate than
other methods
Gas with known
purity, certified
barometer
Gas at elevated
pressure (2-3 bar)
10 min
Higher accuracy than
atmospheric method.
Validation of the
sensor linearity
Requires a certified
pressure gauge Certified pressure
gauge