The Span Functions; Cell Failure - Teledyne 3000PB Operating Instructions Manual

4 Operation
4.4

The Span Functions

The analyzer is calibrated using span gas.
NOTE: Zero is not necessary for Percent (%) level measurements.
Additional information on Zero functions is provided in the
Appendix A-6 of this manual.
Although the instrument can be spanned using air, a span gas with a
known oxygen concentration in the range of 70–90% of full scale of the
range of interest is recommended. Since the oxygen concentration in air is
20.9 %, therefore 20.9% is ideal calibration.
Connect the calibration gases to the analyzer according to the instruc-
tions 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.
Readjust the gas pressure into the analyzer until the flowrate (as read on
the analyzer's SLPM flowmeter) settles between 0.5 and 2.4 SLPM (ap-
proximately 1-5 scfh).
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 section 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.
When the sensor in the 3000PB begins to fail, the analyzer will usually
require more and more frequent calibration. If the 3000PB analysis readings
drift downward uncharacteristically, try recalibration. If recalibration raises
the readings temporarily only, the cell may be failing.
You can check the output of the cell itself by going to the System
function, selecting More, and pressing Enter. The cell output reading will be
on the second line of the display.
The "good" reading depends on the class of cell your analyzer is using.
Although the B-1 cell is standard in the 3000PB, check Specific Model
Information in the Front Matter in this manual for the class of cell you
purchased. Then check Cell Replacement in chapter 5 Maintenance, and do
4-10

Cell Failure

Version Self—Test
Cell Output: ### μA
Teledyne Analytical Instruments
Model 3000PB