Yokogawa Multi Channel Oxygen Analyzer System ZR22/AV550G - Manual (Page 119)

IM 11M12D01-01E 7-9
7. Startup
7.9 Calibration
To calibrate this instrument, the procedure is to measure zero gas and span gas and set
the instrument to read the known concentrations. The procedure for both zero and span
calibration, or for either zero or span calibration, can be performed manually from the
touch display, or can be performed semi-automatically using contact signal inputs to
start calibration, (allowing preset calibration and stabilization times), or it can be
performed automatically at preset intervals. Here we explain manual calibration.
7.9.1 Setting Calibration Gas Concentration
Before calibrating, you need to set the (oxygen) concentration of the gas you will use for
calibration. Here we explain how to do this. Note that calibration-related settings apply
to all channels, you can't set different values for individual channels.
A gas with a known oxygen concentration is used for calibration. Normal calibration is
performed using two different gases: a zero gas of low oxygen concentration and a span
gas of high oxygen concentration. In some cases, only one of the gases needs to be used
for calibration. However, even if only one of the gases is normally used, calibration
using both gases should be done at least once.
The zero gas normally used has an oxygen concentration of 0.95 to 1.0 percent oxygen
by volume with a balance of nitrogen gas (N
2
). The span gas widely used is clean air (at
a dew-point temperature below -20
ЊC and free of oily mist or dust, as in instrument air).
For best accuracy, as the span gas use oxygen whose concentration is near the top of the
measurement range, in a nitrogen mixture.
Shipping-time default setting for zero gas is 1.0% O
2
, and for span gas is 21.0% O
2
.
1) Touch the Setup key to switch to the [Execution/Setup] display.
2) Select [Maintenance] to display the Maintenance display.
3) From the Maintenance display, select [Calibration Settings].
4) Select [Zero Gas Concentration] and touch Enter key to display the numerical entry
display. Enter the oxygen concentration of the zero gas you plan to use. To enter a
concentration of 0.98% O
2
, enter 00098.
5) Select and set the Span Gas in the same manner.
Enter
Calibration setup
F7.9E.EPS
Mode: Auto
᭜ Points: Span-Zero
᭜
Zero gas conc: 0 . 9 8 %
᭜ Span gas conc: 2 1 . 0 0 %
᭜
Timing
᭜ Cal. history initialize
Fig. 7.9 Calibration Setting
Note
If instrument air is used for the span gas, dehumidify the air by cooling to the dew point
of -20
ЊC and remove any oil mist or dust