Delta OHM HD21ABE17, Operating Manual, Page: 26 / 48

HD21ABE17 - 26 - V2.0
2 point calibration:
1. Place the instrument in an environment with known CO
2
concentration between 0
and 950 ppm (for ex. in clean air). For 0 ppm calibration with a nitrogen bottle,
slide the HD21AB17.9 accessory on the top of the instrument by letting the T/RH
probe pass through the central hole and connect the tube from the nitrogen bottle
to the CO
2
input of the accessory; adjust the bottle flow meter to get a constant
flow from 0.3 to 0.5 l/min.
2. Wait about 15 minutes before continuing.
3. Select the 2) 2 Pts Calibration calibration option.
4. Select 1) Calib lower point.
PROBE CALIBRATION
CALIBRATION CO
2
2 PTS CO
2
CALIB
1) Calib lower point
2) Calib upper point
▼▲
select
<ESC> exit/cancel
<ENTER> confirm
5. The instrument display shows the measured CO
2
.
2 PTS CO
2
CALIB
LOWER POINT
START CALIBRATION
CO
2
450 ppm
<ESC> exit/cancel
<ENTER> confirm
6. Adjust the value by using the arrows ▼▲ .
7. Press ENTER on the instrument and wait the time necessary for calibration
without changing the working conditions.
8. When the “CALIBRATION GOOD” indication appears, press ESC to return to the
calibration menu.
9. If the nitrogen bottle was used, close the bottle valve, remove the tube from the
HD21AB17.9 accessory and remove the accessory from the instrument.
10. Place the instrument in an environment with known CO
2
concentration between
1000 ppm and the full scale of the instrument.
11. Wait about 15 minutes before continuing.
12. Select 2) Calib upper point.
13. The instrument display shows the measured CO
2
.