Safety Measures For All Types Of Protection; Type Of Protection "Ex P - Siemens SIPROCESS GA700 Compact Operating Instructions

2.4.2.1

Safety measures for all types of protection

The exhaust lines for the sample gas and reference gas must terminate outside the
hazardous area at a harmless position.
The sample gas exhaust line can also be returned to the sampling point.
OXYMAT 7: When conducting combustible or non-combustible sample gases into the
hazardous area, both the sample gas inlet and outlet must be provided with a flame arrester.
The maximum permissible sample gas pressure in the analyzer depends on the type of
connected gas. Make sure that no higher absolute sample gas pressures occur than
specified in the technical data of the respective device version. The exact specifications of
the sample gas inlet conditions can be found in the section "Technical specifications for
operation in hazardous areas (Page 97)".
Check the tightness of the containment system after all installation and maintenance work.
2.4.2.2

Type of protection "Ex p"

For gas/air mixtures above the LEL, fault tolerance of the containment system is not
guaranteed in the sense of EN IEC 60079-2 and EN IEC 60079-14. Because sample gas
can be released into the pressurized enclosure as a result of leaks (e.g. O-rings). However,
this release of sample gas can be assessed as limited. The maximum quantity released lies
below 200 µl/min, and is guaranteed by the quality assurance measures of the manufacturer
when the analyzer is delivered.
In order to minimize or avoid the accumulation of gases in the enclosure, Ex p devices are
purged continuously with a ignition shield gas (purging gas). Inert gas or air is chosen as the
purging gas.
During the pre-purging phase, before the device is switched on, the purging gas flows
through the enclosure in order to remove any combustible gases that may be present.
During the operating phase the purging gas continues to be fed into the enclosure. This
dilutes any sample gas released through leaks so that an ignitable gas mixture cannot arise.
OXYMAT 7: When conducting purging gas into the hazardous zone ensure that the purging
gas outlet is equipped with a flame arrester.
The specifications for the purging gas are available under: Technical specifications for
operation in hazardous areas (Page 97).
Explosion hazard
The following applies for simplified pressurized devices with type of protection Ex pz for use
in hazardous Zone 2 and Zone 22:
• Never insert combustible gas/air mixtures whose composition lies above the LEL even
Devices in explosion-proof design
Compact Operating Instructions, 05/2018, A5E35134047-03
WARNING
occasionally!
2.4 General directives for explosion protection
Safety instructions
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