Teledyne 3000ZA2G - Zirconium oxide analyzer - Manual (Page 52)

Operation 3000ZA2G
Teledyne Analytical Instruments 40
4.4 The Zero and Span Functions
Note: A zero calibration is required for the zirconia sensor
installed in this instrument. Air must be used for the zero
gas. The Zero calibration will eliminate offset error
contributed by sensor, electronics, and internal and
external sampling system and maintain performance at the
published specification for this instrument.
The analyzer is calibrated using air for zero calibration and a
known concentration of oxygen in a suitable background gas for span
calibration.
The software in the Model 3000ZA2G assumes that air is used as
the zero gas and automatically sets the zero point of the instrument
based on the 20.9% oxygen concentration in air. Do not substitute
another gas for zero gas.
A known oxygen concentration in the range of 70–90% of full scale
of the range of interest is recommended for use as a span gas. The span
gas used must have a concentration greater than 7.0 ppm oxygen. When
70-90% of full scale is close to air concentration (e.g. 0-25% range), 0.1-
1.0% O
2
span gas is recommended.
Connect the calibration gases according to the instructions given in
Section 3.4.1, Gas Connections, observing all the prescribed
precautions.
Shut off the gas pressure before connecting it to the analyzer,
and be sure to limit the pressure to 40 psig or less when turning it
back on.
Adjust the needle valve on the front panel of the analyzer until the
flow rate (as read on the analyzer’s flowmeter) is 0.1-0.3 SLPM.
If you are using password protection, you will need to enter your
password to gain access to either of these functions. Follow the
instructions in Sections 4.3.3 to enter your password. Once you have
gained clearance to proceed, you can enter the Zero or Span function.
4.4.1 Zero Cal
The Zero button on the front panel is used to enter the zero
calibration function. Zero calibration can be performed in either the
automatic or manual mode. In the automatic mode, an internal