Gas Measuring Sensor GMF 4.E.NO2.03
• Monitors the air for toxic gas concentrations,
for example nitrogen dioxide in car parks
• Amperometric measurement principle,
temperature compensated
• Low cross sensitivity to other gases
• Long life
• Use in dusty, dirty rooms is possible
• High accuracy
Technical data
Gas type:
Measuring range:
Occupational exposure limit:
Relative gas density:
Housing:
Dimensions:
Gas supply:
Protection class:
Color:
Measuring principle:
Output signal:
Power supply:
Long term drift:
Linearity error:
Temperature range:
Humidity range:
nitrogen dioxide NO2
0 – 20 ppm
5 ppm
1.59
aluminum
125 x 80 x 57 mm (L x W x H)
diffusion, sintered filter
IP 44
gray
electrochemical
4 – 20 mA linear, 2-wire,
temperature compensated
12 – 36 V DC
1 % per month
< 2 %
-10 °C up to + 40 °C
20 % – 90 % non-condensing
Functional description
The NO2 sensor consists of the housing, the chemical gas measuring cell and electronics. The measuring cell is suitable for the
measurement of low concentrations of nitrogen dioxide in the
air.
The gas sensor operates on the principle of the electrochemical
fuel cell. Molecules reaching the working electrode are oxidized
or reduced. On the counter electrode an oxygen conversion
takes place, which is absorbed or released depending on the
type of reaction.
This measurement principle ensures reliable measurement with
stable zero point and measuring signal. Other advantages are
a low temperature coefficient of the measuring signal, a linear
relation between sensor, signal and gas concentration, as well
as a fast response. The large activity reserve of the working electronics combined with the consistent application of ampero­
metric measuring principle assures a long life.
1.
2.
3.
4.
4.
5.
6.
7.
8.
Electronic circuit board
Potentiometer – 0 calibration, “zero” (40 mV)
Potentiometer – maximum calibration, “span” (200 mV)
Plug 40 – 200 mV
Plug 40 – 200 mV
Terminal strip (x1)
Chemical fuel cell
Gas input
Connection screw joint
Installation
Installation is performed with 2 screws on the wall at a height
of 0.5 m. The gas input should be pointing downward. Shielded
cable such as IY (St) Y 2 x 2 x 0.8 must be used for the electrical
connection. Through the screw-on joint the grounding of the
aluminum housing is assured at the same time because of its
electromagnetic tolerance. Each sensor has to be assigned on
site. Measuring points may not be mounted near air outlets.
The distribution and number of sensors depends on structural
conditions, at least 2 measuring points per monitoring section,
i.e. at least one sensor per 400 m2 garage area.
Gas and CO Alarm Systems | Data sheet No. 37111 | Version 04-2010 | 1 | 2
Gas Measuring Sensor GMF 4.E.NO2.03
Calibration
The sensors are delivered factory calibrated. In case of assembly
times beyond 3 months calibration before start-up is imperative. A breaking-in time of 1 hour must be observed.
Procedure: remove cover from the housing and plug voltmeter
into measuring socket at point X2.
Zero calibration: Use testing gas with synthetic air; adjust pressure valve and flow meter so that approximately 30 l/h flow into
the gas inlet. After about 3 – 5 minutes a stable signal appears;
then adjust potentiometer “zero” to 40 mV.
Calibration for increased levels: Use testing gas with 20 ppm of
NO2. Apply to sensor with the same fittings and the same flow
rate. Set the potentiometer “span” to 200 mV. The calibration is
now complete. If the value 200mV cannot be reached, the fuel
cell is used up and must be replaced with a new one.
Attention, under no circumstances should excess pressure
be applied to the sensor; this would inevitably destroy the
fuel cell.
A recalibration of the system must be performed once a year.
+24
B
TGÜ 04-08
control unit
M
1
2
3
Pressure bottle
Pressure regulating valve
Flow meter
Gas inlet cap
Measuring head
Output in mA
4
8
12
16
20
Output in Voltage
40
80
120
160
200
Circuit board dimensions
4
Operating side view
50 Ω only with
additional
board
Sensor
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2.
3.
4.
5.
Concentration ppm
0
5
10
15
20
Electrical connection
TGÜ 06-28
control unit
Test setup for calibration
of the NO2 sensor
Sensor side view
Sensor
Cable connection exchangeable
Oppermann Regelgeräte GmbH | Im Spitzhau 1 | 70771 Leinfelden-Echterdingen, Germany
Phone +49 711 72 72 35 60 | Fax +49 711 72 80 52 7 | info@oppermann-regelgeraete.de | www.oppermann-regelgeraete.de
2 | 2 | Gas and CO Alarm Systems | Data sheet No. 37111 | Version 04-2010 Specifications subject to change.