Table of Contents
Advertisement
NDIR Gas Analyzer
A manual span calibration is similar to the manual zero calibration. It
involves:
1. Stopping the sample flow and switching to span gas
2. Purging the sample cell with span gas
3. Using the CALIBRATE?/UPS submenu of the MODE menu to
request a manual span calibration.
NOTE:
Before span calibration can be performed, the correct concentration of
the span gas must be entered in the SETUP/CALGAS submenu. If
this value has been previously entered it will be recalled during
startup. You will not need to reenter it unless the memory backup
failed.
To SPAN calibrate your instrument manually:
•
Referring to the flow diagram in Figure 5-1B, make sure that
the 3-way valve labeled A is set to flow SAMPLE gas.
Manually switch valves B to flow SPAN gas.
•
While watching the flow meter, use the needle valve to adjust
the flow to 1.5 SCFH or to the same flowrate that is used for
sample gas.
•
Using the MODE button, navigate to the CALIBRATE?
submenu and while holding in the button, press the UP button
to initiate an upscale (UPS) span calibration.
•
After the CAL DELAY period the instrument will go into
calibration mode and the display will read "DOING UPS
CAL". Calibration data will be collected for 20 seconds.
•
After the 20 second calibration, close the span gas valve and
open the sample gas valve to reinstate the sample gas flow. At
this stage, the composition of the gas in the sample cell is pure
span gas. Purge the cell by allowing span or sample gas to flow
for a sufficient time.
NOTE:
If the TRACK/HOLD function has been set to HOLD (see section 4.3),
then there will be no change in the screen display and the output will
remain fixed on the last reading taken before entering the calibration.
At the end of the 20-second calibration there will be another delay
equal to the time delay set in CAL DISPLAY. This delay is used to
allow sample gas to purge the sample cell of span gas before the
instrument resumes monitoring. It is important to close the calibration
gas valve and open the sample gas valve during this delay to ensure
sufficient purging has occurred before monitoring is resumed.
Teledyne Analytical Instruments., - Rev. 3
Calibration 5
49
Advertisement
Table of Contents
