KCO-NO2 User’s Manual
90-0201-01
Kele • 3300 Brother Blvd. • Memphis, TN 38133
Page: 8
WWW.KELE.COM
Status LED
Color
Operational Status
Description
Concentration is
below the ventilation
threshold. No
outputs are active.
Concentration is
above the ventilation
threshold and below
the alarm threshold.
Ventilation relay is
active.
Concentration is
above the alarm
threshold. Both
ventilation and alarm
relays are active.
Sensor module in
need of service (refer
to Section 6).
Table 3
: Front panel status LED
Indications.
Sensor
Concentration
at 4 mA
Concentration
at 20 mA
CO
0 ppm
200 ppm
NO
2
0 ppm
10 ppm
Table 4
:
Sensor Analog Output Scaling
4 Operational Description
4.1 Normal operation
The KCO-NO2 is a ventilation and alarm
controller that senses the presence of gasoline or
diesel engine exhaust fumes and operates a
Warning contact closure to trigger exhaust fans or
a minor alarm annunciator when elevated levels
of carbon monoxide (generated by gasoline
engines and abbreviated CO) or nitrogen dioxide
(from diesel engine exhaust and abbreviated
NO
2
) are detected. If the concentration of either
gas exceeds its programmed alarm value, a
second set of alarm contacts is operated to trigger
an alarm.
The controller has two independent sensor
modules; one for sensing carbon monoxide (CO),
the other senses nitrogen dioxide (NO
2
). The
sensor modules are field replaceable: each sensor
module 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
).
Mode
Front Cover
LED
Analog
Output
Relays Actuated
Comment
Normal
Steady Green,
Yellow or Red
4 – 20 mA
Depends on
concentration
During normal operation
Standby
Various
4 mA
NONE
During start-up interval or any
time during calibration
Sensor
Error
Slow Blinking
Red
20 mA
Warning/
Ventilation
After calibration of expired
sensor or detection of sensor
failure.
Sensor is no longer operational
and must be replaced.
TABLE 2
:
Operational State Summary
