2
1 EX-TEC OD 4/EX-TEC GM 4 system
The sensor is filled with a liquid (electrolyte), which makes it very
sensitive to high temperatures. The maximum storage tempera
-
ture of 40 °C must therefore not be exceeded. Electrochemical
processes constantly take place inside the measurement cell,
requiring the
EX-TEC OD 4
to be permanently supplied with bat-
tery power at an adequate voltage. For this reason the integral
batteries must not be permitted to reach a state of deep discharge.
When the instrument is not in use it should therefore be stored
in charge-maintenance operation (see section 4.1: Charging and
charge maintenance when using NiMH batteries).
1.1.4
Boundary conditions for measurement and sampling
As well as all sulphur compounds, the electrochemical measure
-
ment cell also reacts very strongly to moisture. Even though this
is rarely important when carrying out measurements in a gas-
distribution network, operators should not blow through sampling
hoses to clear them.
When sampling it is essential to ensure that there are no connect
-
ing pieces made of rubber or synthetic substances between the
EX-TEC OD 4
and the connection to the gas main unless these
consist of inert materials (e.g. Viton or nylon).
A further factor that affects the measurement of sulphur com
-
pounds with the
EX-TEC OD 4
is the flow rate through the mea
-
surement chamber, which must always exceed 20 l/h. Only the
connection hoses supplied with the instrument should therefore
be used for sampling.