K-O2 Oxygen Sensor
5/20/2022
Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133
Page 6
www.kele.com
Status LED Color Operational Status
Description
Concentration is above
the warning/ventilation
threshold.
No relay
outputs are active.
Concentration is below
the warning/ventilation
threshold and above the
alarm threshold.
Warning/ventilation relay
is active.
Concentration is below
the alarm threshold.
Both
warning/ventilation and
alarm relays are active
.
End of Life warning.
Sensor has reached the
end of its rated service life
and should be replaced.
Relays and analog
outputs continue to
function normally.
Sensor Expired.
Warning/ventilation relay
is active and analog
output is 4 mA.
(refer to Section 7)
Table 7:
Front Panel Status LED Indications
During Normal Operation.
4
O
PERATIONAL
D
ESCRIPTION
The K-O2 is a two-stage ventilation and alarm controller that senses the oxygen concentration in the ambient
space around it and operates a Warning/Ventilation contact closure that can be used to operate ventilation fans
when reduced levels of oxygen are detected. If the oxygen concentration approaches unsafe levels, a second
contact closure is operated; typically to trigger an alarm.
The gas sensor is a calibrated module that can be replaced with minimal effort when it reaches end-of-life (EOL),
while leaving the main control mounted and wired (refer to
Section 7.1
).
The front cover has an LED status indicator that illuminates in different colors to indicate normal (green),
Warning/Ventilation (yellow), and Alarm (red) conditions. Blinking red indicates that the sensor is NOT
operational. While the LED is blinking red, the analog output is delivering 4 mA to indicate the error.
The concentration of oxygen in the ambient air is reported at the controller’s analog current-loop output as
percent by volume. The analog output ranges from 4 to 20mA (refer to Table 4 and Table 5).
4.1 S
PECIAL
M
ODES
The K-O2 operates in several modes as shown in
Table
9
.Table
9
: K-O2 Operating Modes
Normal operation is as described above. During standby
mode the sensor is stabilizing and analog output is held at 20
mA.
During span calibration the sensor’s sensitivity is compared
to its sensitivity at initial factory calibration. If its sensitivity
has fallen below manufacturer’s specification the K-O2 goes
into Sensor Expired mode with the analog output held at 4
mA and only the Warning/Ventilation relay activated.
Figure 7
:
Front Cover Status Led