Specifications

PCA
®
3
77
5.7 CO
Low
Sensor Calibration
Note that the CO
Low
sensor also measures H
2
for the purpose of com-
pensating the CO reading for the presence of H
2
in the gas sample. This
procedure fi rst spans the CO
Low
sensor and, optionally, spans the H
2
part
of the sensor to known gas levels.
The user has the option to perform a CO only calibration or a CO/H
2
calibration using the PCA
®
3 soft keys.
Material Required:
• Calibration Kit, P/N 0024-7059
• Gas Cylinder: 500 ppm CO in air, P/N 0024-0492
• Gas Cylinder: 1,000 ppm CO & 1,000 ppm H
2
in Nitrogen, P/N
0024-0794
Procedure:
1. If not already done, turn ON
the analyzer and display the
CALIBRATION LIST screen per
Section 5.2.
2. Use the ▲▼ buttons to highlight
CO
Low
, and then press ENT to display
the CALIBRATE CO screen.
“Measured” is the current CO
reading, while “Applied” is a known
CO level that will be applied for
calibration purposes.
3. Attach a 500 ppm CO cylinder to the
regulator of the calibration fi xture
shown in Figure 5-2 on Page 85.
4. Use the ▲▼ and ◄► buttons to
enter an Applied value that exactly
equals the concentration stamped on
the CO cylinder.
The calibration range is from 9 to
1,500 ppm. An attempt to calibrate outside this range will
cause the message “Applied Value High” (or Low) to appear
at the bottom of the screen.