Teledyne 3060e - Ultra Trace oxygen analyzer User Manual

Page 71

Teledyne Electronic Technologies

Analytical Instruments

4-23

Operations

Ultra

Ultra T

Trace Oxyg

race Oxyg

race Oxygen Anal

en Anal

en Analyz

yzer

Analyze Mode

After initial start-up, the analyzer automatically enters the Analyze mode. In the
Analyze mode, the sample gas is constantly monitored while four menus are
offered: Calibration, Setup, Range, and Stand-by. You can enter any of these
menus from the Analyze mode, and return to the Analyze mode once you are
done.

Before analyzing a sample gas, the analyzer must be first spanned and then
zeroed. During span calibration, a gas with a known concentration of oxygen
is sent to the Ultra Trace sensor and a reading is kept in computer memory. The
span of the analyzer is automatically adjusted to produce a signal readout that
is equivalent to the known concentration of oxygen supplied in the span gas.
The analyzer can be span calibrated with either the Faradaic calibrator in the
system or a span gas of your choice. During the zero calibration process, the
analyzer transports the sample gas through the built-in scrubber, which
removes all of the oxygen in the gas and produces the zero gas. The zero gas
is then sent to the Ultra Trace sensor, where the reading is recorded into
computer memory.

Both span and zero functions can be set to run automatically at specified
intervals in the Setup mode.

Conditioning the Ultra Trace Sensor

Raw output from the Ultra Trace sensor is typically between 16–18

µΑ

/PPM

of oxygen. If the output is below 6

A/PPM, the microprocessor will send an

error message "CELL TO WEAK". On the other hand, if the output is above
18mA /PPM, the microprocessor will send an error message "CELL TO
STRONG". In either case, the microprocessor will be unable to adjust the span
sensitivity.

The Ultra Trace sensor is qualified at the factory by measuring its raw output.
However, when the analyzer is shipped to the user, the sensing element of the
Ultra Trace sensor becomes dry and the output may become lower than the
acceptable limit. Therefore, when the analyzer is placed into service for the very
first time, it may become necessary to condition/activate the Ultra Trace sensor
before attempting span and zero calibrations. This is done by introducing a span
gas between 5–9 PPM (either from an external source or generated by the built-
in Faradaic calibrator) until the sensor output is at least

of the span gas.