Datasheet
6 DKRCI.PD.S00.A4.02 / 520H2142 © Danfoss A/S (RC-MDP/MWA), 2014-04
Gas Detection Sensor, type GDA, GDC, GDHC, GDHF, GDH
Sensor technology Danfoss has, depending on actual ppm range and
refrigerant, selected the most appropriate sensor for
the target refrigerant gas. When the refrigerant and
actual ppm range has been decided, the Danfoss
The calibration procedure consist of:
Annual checks by qualified bump test
Calibration by replacement of the sensor PCB with a
Danfoss pre-calibrated certified sensor PCB
Calibration / test methods
Method I
Calibration / test by means of
replacing Sensor PCB
This method requires that Danfoss offers factory
calibrated PCB sensor boards with calibration certificate
and traceability codes. Additionally an electrically
simulation is required to verify the output signals and
alarm settings.
The PCB sensor board, which is the essential measuring
element of the gas detector, is produced, calibrated,
tested and certified by Danfoss.
After the main PCB of the gas detector has been tested
with the GD tester, the new calibrated Sensor PCB can
be installed.
Danfoss recommends that the calibration / test
procedure is done by means of replacing the Sensor
PCB, because:
No need to purchase calibration gases in several
different concentrations
Simpler and quicker than gas calibration
Danfoss guarantees the correct calibration and
functioning of the new sensor PCB, which is
supplied with a calibration certificate.
No problems with sensor deterioration or end-of-life
Price competitive, compared to the gas calibration
carried out on site.
Electrochemical Sensors - EC
EC sensors are used mainly for toxic gases and are
suitable for ammonia but not for the other refrigerants.
They are very accurate and tend to be used principally
for toxic gases which cannot be otherwise detected or
where high levels of accuracy are needed.
Semi-conductor – SC
SC sensors can be used for a wide range of gases
including combustible, toxic and refrigerant gases.
The SC sensors are low-cost, long life, sensitive, stable,
resistant to poisoning and can be used to detect a
large range of gases including all the CFC, HCFC, HFC
refrigerants, ammonia and hydrocarbons.
However, they are not selective and are not suited to
detecting a single gas in a mixture or for use where
high concentrations of interfering gases are likely to be
present.
GD product range makes it easy to pick out the right
product.
Below is a brief introduction to the GD sensor types.
For further information - please contact Danfoss.
Catalytic - CT
CT sensors have been mainly used for combustible
gases including ammonia. CT are relatively low-cost,
well established and understood and they have a
good life span, up to 5 years. They can be subject to
poisoning in certain applications but not generally in
refrigeration and are more effective at gas levels of
above 2,000 ppm.
Infrared - IR
IR sensors are very specific and is very precise for
detection of CO
2
.
Annual Test
To comply with the requirements of EN378 and the F GAS regulation sensors must be tested annually.
However local regulations may specify the nature and frequency of this test. If not the Danfoss
recommended bump test procedure should be followed. Contact Danfoss for details.
For increased accuracy the unit must be calibrated at the temperature of operation.
After exposure to a substantial gas leak, sensor should be checked and replaced if necessary.
Check local regulations on calibration or testing requirements.
Certificate
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Certificate:
Gas / calibration levels etc.
Traceability
Ex
change of PCB
sensor board
+
Electrical
test of alarm
Gas sensor
tested
Test and calibration of GD Main
Board by the use of GD tester