Calibration; Calibration Fluids - Teledyne 7120 Operating Instructions Manual

Photometric Analyzer
1. Repeat the Self-Diagnostic Test, section 5.2
2.6

2.6.1 Calibration Fluids

Zero and span fluids must be made by the chemistry lab or certified zero
and span gas bought from a gas supplier. The zero fluid must be the major
component of the sample, free from the component of interest. In purity
applications, the accuracy is only as good as the purity of the zero gas used to
reference to. The 7120 has a continuous flowing optical reference gas path that
the sample is compared to, so it must be very pure, i.e, CO2 purity of 99.995%.
Typically this reference flow is about 20 ccm.
Note: In Non-purity applications, the reference cell may be sealed
with clean air (consult factory).
The span fluid must be the major component of the sample mixed with
a small amount of the component of interest. The concentration must be 80 to
95% of the full scale range or the widest range of the instrument (if the instrument
provides more than one range). (i.e, for a 98-100% CO2 range purity, use span
of 98.40% N2 in 99.995% pure CO2).
Refer to Section 4.4 of the manual to determine how to manipulate the
mode setting. The recommended calibration method is as follows:
1. Calibration with zero and span fluids. (Note: Zero gas may be 100% gas
in purity applications).
Method:
1. Introduce zero fluid and set zero as referred in section 4.4.1
NOTE: When calibrating from 0% to an upper concentration gas, obtain
a zero gas (minus the analyte) that typically is as pure as the minimum resolution
needed to control to. This usually meets or exceeds the minimum full scale
accuracy of the measurement.
2. Introduce a span fluid and set the concentration of the span fluid.
Refer to the span procedure in section 4.4.2. (Note: The span gas should
typically be an 80% of full scale range gas similar to the 100% zero gas
background; i.e., 100% CO2 zero gas and a span gas of 98.4% CO2 in N2 for
a 98-100%CO2 purity application.

Calibration

2.6.2 Calibration
Teledyne Analytical Instruments
Installation 2
2-15