Dokument
IMA 190
HFE507
Rev
5
Sid
41 (44)
Functional test
The unit has three LED’s – green, yellow and red. These LED’s indicate the status of
the controller. An internal delay function prevents the alarm functions of the relay and
OUT4 output during 2 minutes after power up. The alarm outputs may be tested after
the 2 minutes delay
Green LED
- ”No alarm situation” is lit, when the relay is contact closed.
Yellow LED -
”Call for maintenance” is lit, if an error flag is set or the measurement is
out of range. This information is also shown on the display by the wrench icon. Any
push button press, or executed maintenance function, is acknowledged by emission
from this LED. If an error has been detected both the yellow and red LEDs are lit.
Red LED
- ”Alarm high gas concentrations” is lit, when the open collector output is
activated (contact closed). The CO concentration is 35 ppm or more OR the CO
2
concentration is 1500 ppm or more OR if the yellow LED is lit.
A simple and visual functional test can easily be performed. Take a breath and blow
the air from a distance of a few centimetres on the sensor. The sensor will detect a
rapid increase in the carbon dioxide concentration.
If cigarette smoke is blown into the sensor there is also a registration of increased
CO level. The CO sensor reacts much slower (several minutes).
The red LED is lit and the green LED is turned off when the CO or CO
2
concentration
goes above the pre-set value. If the sensor is connected to a controller, the flow of
the ventilation system will eventually increase by change of the fan speed or opening
of a damper actuator.
Test gas verification
If the measurement of a sensor is to be verified, a test gas with carefully determined
concentration of CO and CO
2
must be used. For zero calibration pure nitrogen or air
that has passed through a chemical absorber should be used. In fresh air the carbon
monoxide concentration is nearly zero. The Zero calibration bag can be used to
produce carbon dioxide free air. Check the CO and CO
2
values of the display or the
voltage of the output 1 for CO and the voltage of the output 2 for CO
2
with a
multimeter when the values have stabilized.
When a zero calibration shall be executed a plastic tube with 2,2 mm outer diameter
and 0,8 mm inner diameter shall be inserted in marked holes of the sensor. A plastic
tubing is connected to the tube. The gas flow should be between 0,3 and 1,0 l/min.
When a calibration is executed the yellow LED flashes. A calibration will only be
executed if the gas concentration is stable. If the yellow LED does not flash after 8
seconds no calibration has been executed. Then try to do another calibration.
