Ultra Trace Oxygen Analyzer Operation 4
4-11
Teledyne Analytical Instruments
4.3.7 Filter Function
The response time on the most sensitive range (ppb range) is user
definable from approximately 1-60 minutes. The adjustable filter allows the
user to tune the response of the analyzer to best balance sensor noise and
response time requirements. The factory default setting is 5 minutes. The
actual response time will depend on the user’s sample system (the length and
size the tubing of tubing as well as the sample flow rate).
The filter setting can be accessed by selecting SYSTEM on the keypad
followed by MORE on the display with the <> keys. The filter function is
then selected and changed using the arrow keys. Press ENTER and ANA-
LYZE to return to analyze mode.
In the event of an over-range condition, the filter rate will automatically
switch to a faster setting (approximately 45 sec. response time) for the
duration of the over-range or upset condition. This feature allows the ana-
lyzer to quickly respond to and track an upset condition.
4.4 Calibration of the Analyzer
The analyzer must be calibrated prior to its use. For most applications
where the desired range of measurement is 0 to 10 ppm, or less we
recommend the analyzer be calibrated using a span gas as detailed below:
Span Gas Calibration
Before the cell is ready for calibration, it must be purged with sample
gas to a low oxygen level preferably below 0.1 ppm. However, if the
oxygen contact of the sample gas is higher than 0.1 ppm, a zero gas such as
nitrogen with oxygen level below 0.1 ppm may be required.
The recommended span gas concentration is between 7.0 to 9.0 ppm
oxygen in nitrogen, and will require calibration be performed in the 0-10
ppm analyzer range.
4.4.1 Zero Cal
The B-2CXL cell has a zero offset of less than 0.1 ppm oxygen. Nor-
mally, the offset slowly decreases during the first 7 to 10 days of operation,
and is expected to reach a steady value after this time.