Emerson Rosemount X-Stream Series, Инструкция по эксплуатации

Страница: 84 / 536

Emerson Process Management GmbH & Co. OHG
3-10
X-STREAM XE
Instruction Manual
HASXEE-IM-HS
10/2012
3.2 Oxygen Measurement
Due to the measuring principle the electro-
chemical oxygen cell requires a minimum
internal consumption of oxygen (residual
humidity avoids drying of the cell). Supplying
cells continuously with dry sample gas of low
grade oxygen concentration or with sample
gas free of oxygen could result in a reversible
detuning of O
2
sensitivity. The output signal will
become unstable, but response time remains
constant.
For correct measurement the cell needs con-
tinuously to be supplied with concentrations
of at least 0.1 Vol.-% O
2
. We recommend to
use the cells if need be in alternating mode,
means to purge cells with conditioned (not
dried, but dust removed) ambient air when
measurement pauses.
If it is necessary to interrupt the oxygen sup-
ply for several hours or days, the cell has to
regenerate (supply cell for about one day with
ambient air). Temporarily flushing with nitrogen
(N
2
) for less than 1 h (e.g. for analyzer zero-
ing purpose) has no influence on measuring
characteristics.
Gas
Concen-
tration
Interference
Level
Carbon monoxide CO
0-100 % no effect
Carbon dioxide CO
2
0-100 % no effect
Nitric monoxide
NO
0-1 % no effect
Nitrogen dioxide
NO
2
0-1 % no effect
Sulfur dioxide
SO
2
0-3 % 3 %
Hydrogen sulfide
H
2
S 0-3 % no effect
Ammonia NH
3
0-3 % 1 %
Hydrogen H
2
0-100 % no effect
Hydrogen chloride HCl 0-3 % 1 %
Benzene C
6
H
6
0-100ppm 1 %
Methane CH
4
0-100 % no effect
Tab. 3-4: Electrochemical Oxygen Measurement -
Cross Interference by Accompanying
Gases
3.2.2.1 Special Hints
This sensor is not suitable for
•
anorganic gases containing
chlorene or flourene!
•
sample gases containing
•
FCHCs
•
ozone,
•
H
2
S (> 100 ppm)
•
NH
3
(> 20 ppm).
For a number of other interfering gases
Tab. 3-4.
Note for XEGP analyzers!
If the XEGP analyzer features thermostate
control, the eO2 sensor block is installed at
the XEGP rear panel.
Fig. 3-8: Cover for EO2 Sensor Block At Rear Panel
Cover