DESCRIPTION
The 7823-X Series Standard Temperature
Oxygen Analyser is designed to determine the oxygen
concentration in air or inert gas mixtures with temperatures
of -100 to +250
°
C max.
The 7823-X-H Series High Temperature Oxygen
Analyser is designed to determine the oxygen
concentration in air or inert gas mixtures with temperatures
of -100 to +400
°
C max.
These products are particularly suitable for measuring
oxygen in areas that are not easily accessible, or in
closed systems, such as ventilation pipes, flues and
containers.
The 7823 Series can be user configured to output
measuring ranges of 0-25% O
2
and 0-100% O
2
. The entire
measurement range is linear in both cases. Factory default
is 0-25% O
2.
When configured for 0-100% O
2
the user can
also customise the analogue output ranges to suit their
application.
The outputs can be configured to either
4-20mA and 0-10V
DC
or RS232 interface. Prior to
shipping all 7823’s are preconfigured with a
measuring range of 0.1%
to 25% Vol. O
2
with linear
4-20mA and 0-10V
DC
outputs.
All settings can be changed by the customer should their
measurement or interface requirements change by simply
altering the position of jumper links on the PCB.
The actual oxygen sensor is mounted in the tip of the
stainless steel probe and is protected by a stainless-steel
sintered cap which acts as both a large particulate filter
and also as a flame trap. The IP65 waterproof die-cast
aluminium housing accommodates the electronics and is
mechanically connected to the sensor probe.
The 7823 outputs the measured values
simultaneously via 2 output channels (4-20mA and
0-10V
DC
or RS232 Rx and Tx) both channels are
referenced to the system GND.
A digital 3.3V
DC
logic output cycles at the same
frequency as the electrochemical pumping action of the
oxygen sensing cell during normal operation, thus
providing a real time sensor health check, if the output
ceases to cycle the sensor has entered a start-up or error
state. This provides fault proof operation. The digital
output is also used during the calibration process to
indicate the interface status.
A green on-board LED mirrors the CYCLE output and can
be used to visually determine the sensor status or during
the calibration process. A red LED indicates the unit has
power applied.
E
igroup
range of oxygen sensors do not directly measure
the oxygen concentration but instead measure the partial
pressure of oxygen within the measurement gas. In order
to output an oxygen concentration (%) the 7823 must be
calibrated, or more specifically, re-referenced in a known
gas concentration, typically normal air.
Calibration, or re-referencing, is achieved by connecting
the calibration input to GND and monitoring the status of
the digital cycle output or by visually monitoring the on-
board green LED. During the calibration process the out-
put will either automatically calibrate to a fixed reference
or can be manually calibrated to any output by way of a
PCB mounted potentiometer. The fixed reference is
factory set to 20.7% O
2
for calibration in normal air
though this value may be altered via the RS232 interface
for calibration with a reference gas of any known oxygen
concentration. Calibration is stored on power loss.
Again the auto or manual calibrate function is user
configurable. Regular calibration removes the effects of
application and atmospheric pressure changes and also
eliminates any sensor drift that may occur during the first
few hundred hours of operation.
7823
Oxygen Analyser
ECO
line
7823 Oxygen Analyser
E instruments
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