Calibrator - Teledyne 306WA Instruction Manual

2.0 Operational Theory 2.0 Operational Theory 2.0 Operational Theory 2.0 Operational Theory 2.0 Operational Theory
the humidifier column equal to the water column from the bottom of the
reservoir to the water level in the reservoir. Thus, the water level in the
humidifier column is held even with the sample connection at the bottom of
the reservoir. There will be a slight additional pressure in the top of the
humidifier column depending on the flow rate (the pressure needed to push
the sample through the cell and associated tubing), but at normal flow rates
this merely slightly lowers the level in the humidifier column.
The sample bubbles through the water in the reservoir on its way to the
outlet port. Some of the water vapor will re-condense, so that the sample
flows out of the outlet port saturated at the reservoir temperature, which is
slightly above ambient. The sample bubbling through the make-up water
will scrub out any oxygen which may be dissolved in it. This assures that the
sample will not pick up any oxygen as it passes through the humidifier
column.

2.4 Calibrator

2.4 Calibrator
2.4 Calibrator 2.4 Calibrator 2.4 Calibrator
The number of electrons flowing through the measuring cell's load
resistance (the output current) is directly proportional to the amount of
oxygen that has reacted. If no oxygen is present, no output current flows,
giving the analyzer an absolute zero. No zero adjustment is required. The
analyzer can be completely calibrated with only one standard sample,
instead of the two usually required for process analyzers.
If the oxygen content indicated by the analyzer is plotted as ordinate
against the actual oxygen content as abscissa on a simple graph, the condi-
tion of proper calibration is represented by a straight line starting at the
origin with a slope of 1 (see Figure 2). If the analyzer has a low sensitivity,
the slope will be greater than 1. In each case, however, the line passes
through the origin because of the absolute zero, and the slope is determined
by the sensitivity adjustment. Thus, the analyzer can be completely cali-
brated by adjusting the slope of this curve; i.e., by adjusting the span so that
the change in output indication is equal to a known change in actual oxygen
content of the sample. This can be done by adding a known amount of
oxygen to the sample flowing through the analyzer, even though the amount
of oxygen in the sample is now known. Refer to section 4.7.1: Calibration
The calibrator provided is an electrolysis cell in which water is con-
verted to hydrogen and oxygen by an electric current.
The concentration of oxygen added to the sample can be calculated
from the amount of current passing through the calibrator and the sample
flow rate.
2-4
TELEDYNE ELECTRONIC TECHNOLOGIES
Analytical Instruments
Model 306W Model 306WA A A A A Model 306W Model 306W Model 306W
4.7.1: Calibration. 4.7.1: Calibration 4.7.1: Calibration 4.7.1: Calibration