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Dräger Polytron Ex User Manual

Dräger Polytron Ex
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Start-Up
Page 18 of 40
9023744 - 3rd edition - October 2005
Check the Measured Value Output
During calibration:
Compare measured value indicated on the transmitter’s display with the reading
of the corresponding central unit (e.g. channel module Polytron or Regard)
or
Check alarm triggering by supplying a test gas (concentration somewhat higher
than the alarm threshold) to the Ex-sensor.
Testing the Constantly Amplified Sensor Signal (Sensitivity)
Perform zero calibration as described under “Calibrating Transmitter Polytron Ex”
resp. “Calibrating Transmitter Polytron Ex R" (page 15 resp. page 16).
1 Set sliding switch to position »2« = test.
The measurement signal of the 4 to 20 mA loop oscillates between 2.5 and 5 mA
with approx. 1 Hz, thus preventing alarm triggering.
The display shows a 3-digit number without a decimal point.
Depending on the Ex-sensor used supply the recommended calibration gas con-
centration (s. table below) at a flow rate of approx. 0.5 L/min via the calibration
adapter.
The calibration gas must be a mixture of the gas component to be monitored in
air. Mixtures with nitrogen are not suitable!
Once measured value display has stabilized (after max. 3 minutes):
Divide the displayed value by the gas concentration (in % LEL) to obtain the sen-
sitivity E:
E =
Displayed value
,
[ 1 ]
gas concentration [ % LEL ]
Keep sensitivity E for reference purposes when performing repeat measurements
during operation period.
This test must be performed at regular intervals and following repairs. The results
are to be compared with the result of the measurement performed on start-up.
If the sensitivity drops below 50 % of the sensitivity on start-up, then the Ex-sensor
is to be replaced.
Ex-sensor resp.
Sensing head
Full scale value Calibration gas concentration
Ex-sensor PR M
Sensing head SE Ex PR M
100 % LEL 10 to 50 % LEL
Ex-sensor LC M
Sensing head SE Ex LC M
10 % LEL 3 to 7 % LEL
02923744_1_en.eps
1
Test gas
03023744_1.eps
1
03123744_1_en.eps
Test gas

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Dräger Polytron Ex Specifications

General IconGeneral
BrandDräger
ModelPolytron Ex
CategoryTransmitter
LanguageEnglish

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