Notes For Co Adjustment; Using Calibration Gas Vs. Ambient Gas; Effect Of Temperature On Co Measurement - Vaisala CARBOCAP GMW90 Series User Manual

User's Guide _______________________________________________________________________
64 ___________________________________________________________________ M211659EN-C
Notes for CO
1-point CO adjustment affects either offset or gain, depending on the gas
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concentration. 1-point adjustment below 700 ppm affects the
measurement offset, above 700 ppm it affects the gain.
2-point adjustment will adjust both offset and gain. Choose the
adjustment points as follows:
- For first point, use as low concentration as possible. Preferably 0 ppm,
must be below 700 ppm.
- For second point, use as high concentration as is relevant for your
application. Must be within 700 ... 5000 ppm.

Using Calibration Gas vs. Ambient Gas

You can adjust using a calibration gas with a known concentration
(recommended), or adjust using the ambient gas:
- When using a calibration gas, feed the gas to the adjustment inlet at a
flow rate of 0.3 ... 0.7 L/min. For location of the inlet, see Figure 2 on
page 15. After connecting the gas supply to the field adjustment inlet,
wait for at least three minutes for the reading to stabilize.
- When using ambient gas for adjustment, avoid breathing near the
transmitter during the adjustment.
Regardless of the CO
measurement stabilize before performing the adjustment. Three minutes
is typically enough. Also allow for the stabilization period after
adjustment, before verifying the result.
Effect of Temperature on CO
The device is fully temperature compensated using internal temperature
measurement.
Adjustment
2
reference used, it is important to let the CO
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2
Measurement
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