Teledyne Analytical Instruments 311PC, Instruction Manual

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4–4
4 Maintenance Model 311PC
Teledyne Analytical Instruments
Notes:
1. This curve assumes continuous exposure.
2. Intermittent exposure will extend life. In general,
the CO
2
effect is cumulative and the average CO
2
concentration should be used to find the predicted
cell life.
3. Cells can be used to make spot check
measurements of O
2
in the presence of high
concentrations of CO
2
(up to 50% and more). The
CO
2
containing sample should be purged out as
soon as a constant reading is obtained.
4. Abnormally slow response and recovery is
characteristic of cells operated as indicated in
notes 1, 2, and 3.
5. The reduction in cell life is primarily due to a
drop in output. This reduces to a point where the
instrument can no longer be spanned. Instruments
using B-1 cells in CO
2
atmospheres should be
spanned more frequently (at intervals 10-20% of
the predicted life).
6. The CO
2
effect on B-1 cells is independent of the
O
2
level. The reduction in cell life due to their
being used in CO
2
atmospheres is therefore
limiting and takes precedence over the normal
warranty.
Figure 4-1: The Effect of CO
2
on B-1 Cell Life
0,0
4
8 12 16 20 24 28
1
2
3
4
5
6
7
8
9
10
% C
a
rbon D
io
x
id
e
Predicted Weeks of Cell Life