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Emerson Process Management GmbH & Co. OHG7-48
X-STREAM X2
Instruction Manual
HASX2E-IM-HS
02/2012
In consequence of it‘s design the sensor‘s
lifetime is limited and depends on theoretical
designed life and Oxygen concentration.
The sensor output can be taken as a rough
criterion for end of lifetime: The sensor is
worn-out when the output in atmosphere is
below 70 % of the initial output. The period
till then can be calculated by
The sensor‘s designed life under constant
conditions of 20 °C is approx. 900,000 hrs.
The lifetime at 21 % Oxygen is therefore
calcu-lated to approx. 42,857 hrs, corre-
sponding to approx. 5 years.
Irrespective of all calculations above:
A sensor is worn-out if, connected to am-
bient air, the output voltage is less than
2.8 V: Replace the sensor!
Note 1!
The given lifetime values are for reference
only! The expected lifetime is greatly affec-
ted by the temperature of the environment in
which the sensor is used or stored. Increases
or decreases in atmospheric pressure have
the same effect as that by increases or de-
creases in Oxygen concentration. (Operation
at 40 °C halves lifetime).
Note 2!
Due to the measuring principle the electro-
chemical Oxygen cell requires a minimum
internal consumption of Oxygen (residual
humidity avoids drying up 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 re-
mains constant.
For proper measurement results the cell
needs to be supplied continuously with con-
centrations of at least 0.1 Vol.-% O
2
.
We recommend using the cell if need be in
alternating mode, means to purge the cell
with conditioned ambient air (not dried, but
dust removed) when measurement pauses.
If it is necessary to interrupt Oxygen supply
for several hours or days, the cell has to rege-
nerate (supply cell for about one day with
ambient air). Temporary ushing with Nitrogen
(N
2
) for less than 1 h (e.g. for analyzer zero-
ing purpose) has no inuence on measuring
characteristics.
designed life (hours)
O
2
concentration (%)
Lifetime =
For replacing the electrochemical sensor the
following tools are required:
• Philips screw drivers # 0 & 2 for tabletop/
rackmount instruments or square key for
the eld housing's squash fasteners or
allen key for the ameproof analyzer to
remove/open the cover/front door.
• Torx screw driver # 10.
• 1 digital volt meter (measuring range
0…2 V dc minimum) with suitable cables
and probes.
Consider all applicable safety
instructions, especially those at
the beginning of this section 7.5
7.5 Replacing Worn Out Sensors