Siemens ULTRAMAT 6F Manuel d'utilisation - Page 27
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4.5.4
Connection of sample gas and protective gas (purging gas)
Analyzers used in hazardous areas must be purged with air or inert gas. The gas discharged by purging must be routed via
an exhaust gas line for environmentally-friendly disposal.
When measuring toxic or corrosive gases, it could occur that sample gas accumulates in the analyzer because of leaks in
the gas path. No gases containing potentially hazardous concentrations of toxic, corrosive or combustible components may
therefore be connected to restricted breathing devices (Ex nR).
Analyzers provided with heating must always be purged when using with corrosive gases.
Secure the analyzer and the Ex px safety equipment in accordance with your dimensional drawings in section Connection
diagrams (Page 23), and connect them as shown in the assembly diagrams 4-2 and 4-3. The following information applies to
use of the Ex px safety equipment recommended by us in accordance with our current Catalog AP01. This information
applies accordingly to all other purging units.
It is essential that you observe the following conditions for trouble-free operation:
● When tightening union nuts on the gas couplings, use a suitable open-ended spanner to achieve correct counterlocking;
otherwise the danger exists that the gas path will leak.
● The operator must ensure the minimum pressure of the protective gases at the installation site. An overpressure of
0.2 ... 0.4 MPa (2 ... 4 bar) must be applied at the pressure regulator of the Ex px safety equipment.
● If the protective gas is discharged, the pressure drop over the line must not exceed 5 hPa (5 mbar) at a flow of 50 l/min.
To achieve this, the exhaust air line must be dimensioned accordingly (e.g. for a pipe thread with inside diameter of ISO
228 - G 1, the length of the exhaust air line should be about 20 m).
● The pre-purging time which can be set on the Ex px safety equipment (5 min with a protective gas flow of 50 l/min) must
not be changed (this is the minimum!).
● The Ex px safety equipment is delivered with fixed basic parameters. The protective gas pressure is preset to 105 hPa
(rel.). Reasonable changes to these parameters, such as reduction of the maximum protective gas pressure, can only be
made in accordance with the specifications in the supplied manual for the Ex px safety equipment.
● Sample gas must not be supplied to the analyzer until the pre-purging phase has ended.
● A key switch can be connected to the Ex px safety equipment (see Key switch (Page 33) for details).
● OXYMAT 6F: Before sample gas is fed in, the microflow sensor must be purged by reference gas. Therefore the
reference gas must also be connected (pre-purging period = 5 min) when the Ex px safety equipment is switched on. The
reference gas pressure must always be 0.2 ... 0.4 MPa (2 ... 4 bar) above the sample gas pressure.
For analyzer versions with leakage compensation, the following also applies:
For operation with combustible sample gases, the difference in pressure between the protective gas and sample gas must
be permanently and reliably kept at over 50 hPa (recommended 5 hPa). Differential pressure monitoring must be provided
for failure protection. This should ensure that the Ex px safety equipment switches off the analyzer and goes into the pre-
purging phase when a set pressure difference is fallen below. It is up to the user to select a suitable differential pressure
monitoring device (e.g. differential pressure switch).
OXYMAT 6F: The sample gas inlet contains a restrictor that creates a dynamic pressure to dampen pulsating flows.
Removal of this restrictor may be advisable if differential pressure monitoring (with leakage compensation) is to take place.
The damping measure (restrictor) should then be fitted upstream of the pressure measuring point if required.
Compact Operating Instructions in accordance with EN 61010-1 and EN 60079-0
A5E45779389002-01, 09/2018
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