Hints for Safe Use
9023744 - 3rd edition - October 2005
Certain substances in the atmosphere to be monitored may impair the sensitivity of the sensing heads with Ex-sensor PR M resp.
Ex-sensor LC M.
The following substances are known at present:
a) Polymerizing substances such as Acrylo nitrile, Butadiene and Styrene,
b) Catalyst poisons such as sulphurous or phosphorous compounds, halogenated hydrocarbons, silicon compounds, and metal-
organic vapours.
If such substances are expected to occur in the atmosphere to be monitored, the calibration intervals should be shortened. This
is also recommended by the European Standard EN 50 073.
Intrinsic Safety Concept:
— Explosion protection acc. to CENELEC:
— Sensor replacement and maintenance is possible without switching off the supply voltage.
The transmitters Polytron Ex resp. Polytron Ex R with sensing head SE Ex is marked by the device category
II 2G
and is suitable
to be operated in hazardous zones 1 and 2.
The ex-approval is valid for the transmitters resp. sensing heads being operated in mixtures of flammable gases and vapours in
air. Especially the ex-approval is not valid for the operation in oxygen enriched atmospheres.
Transmitter with measurement function for explosion protection according to 94/9/EC
Only the transmitter Polytron Ex (order no. 83 17 517) mit dem Ex-Sensor PR M (Sachnummer 68 09 225) with the Ex-sensor
PR M (order no. 68 09 225) has been certified in the 1st supplement to the EC type test certificate BVS 03 ATEX E 160 X as
suitable for use with the following gases and vapours as regards the measurement function for explosion protection:
Methane, propane, hydrogen, n-butane, ethene (ethylene) dimethylether, acetone, ammonia, gasoline 065/095 (FAM petrol),
benzene, 1,3-butadiene, cyclopropane, diethylether, acetic acid-n-butylester (ethyl acetate), ethanol, ethyl acetate, ethylene oxide,
n-hexane, methanol, methyl ethyl ketone (MEK), n-nonane, n-octane, 2-propanol (isopropanol), propene (propylene), toluene,
acetylene, propylene oxide and n-pentane.
The following special conditions must be observed for safe use when using as a transmitter with a measurement function for
explosion protection:
1. The heat-of-reaction measuring principle, based on catalytic oxidation of a flammable gas, is not absolutely reliable because
at high measured gas concentrations the oxygen concentration in the sensor is no longer sufficient to oxidize the flammable
gas. The measuring signal is thus diminished at very high gas concentrations and may reach values inside the measuring
range. The downstream controller must be operated with display devices and measured value outputs (if implemented) and
alarm outputs which lock if the measuring range is exceeded.
2. The heat-of-reaction measuring principle requires a minimum oxygen content of 12 % V/V. Otherwise too low measured values
are displayed, due to the oxygen deficiency.
3. When the supply voltage is switched on, the transmitter may briefly (approx. 100 ms) send a current up to 12 mA to the central
unit, exceeding the local alarm thresholds. To avoid this happening, the alarms at the central unit should be locked during the
switch-on procedure.
Transmitter Polytron Ex:
EEx me [ib] IIC T4
Transmitter Polytron Ex R:
EEx me [ib] IIB T4