Siemens ULTRAMAT 6F Operating Instructions Manual page 8

2.2.4 Further safety measures
The exhaust lines for the sample and reference gases must terminate outside the hazardous area at a safe place. The
sample gas exhaust line can also be returned to the sampling point.
When sample gases (both combustible and non-combustible) are discharged into the hazardous area, you provide the
sample gas inlet and outlet with a flame arrestor each.
When combustible media are supplied, you must interrupt the sample gas supply after switch-off of the analyzer and
pressurized enclosure or when the pressurized enclosure responds under fault conditions.
The maximum permissible sample gas pressure in the analyzer depends on whether the introduced gas type is combustible
or non-combustible and is described in the technical specifications under the point "Sample gas inlet conditions".
See also
Technical specifications for operation in hazardous areas (Page 42)
2.2.4.1 Analyzer versions Ex px with leakage compensation
The containment system (sample gas path in the analyzer) is rated as without release if
● the gaseous medium is not combustible,
● the gaseous medium is combustible, but the gas concentration is always below the lower explosion limit which must be
guaranteed by a safety level of at least
● the gaseous medium is combustible, and the differential pressure between the enclosure and the containment system is
monitored. The pressure in the enclosure must always be at least 50 Pa (recommended 5 hPa) above the pressure in
the containment system and the environment.
Monitoring of the differential pressure between the enclosure and the containment system must be carried out at the
following safety level:
– the pressure monitoring of the containment system by the system itself is at least
(operational reliability) and the differential pressure monitoring between the containment system and the protective
Category 1 to EN ISO 13849-1
gas is at least
– the differential pressure monitoring between the containment system and the protective gas corresponds to at least
Category 3 from EN ISO 13849-1 (fault tolerance, single fault tolerant)
the level of
dependent safety.
The assessment of the safety level of the monitoring devices also includes faults in the pressure and gas lines. When
assessing the safety level of the monitoring devices, it is assumed that the monitoring devices are independent of one
another. When the monitoring devices are coupled to perform an overall function, this must be guaranteed with a safety level
Category 3 according to EN ISO 13849-1
of at least that of
Alternatively, a comparable international standard can be taken as the basis for
2.2.4.2 Analyzer versions Ex px with continuous purging or Ex pz with use of the containment
system
With gas/air mixtures above the LEL, fault tolerance of the containment system is not guaranteed in the sense of
EN/IEC 60079-2 since sample gas can be released into the pressurized enclosure as a result of leaks (e.g. O-rings).
However, this release can be assessed as limited. The maximum quantity released is below 200 µl/min, and is guaranteed
by the quality assurance measures of the analyzer manufacturer when the analyzer is delivered.
Continuous purging of the Ex p enclosure must therefore be carried out following the pre-purging phase. This guarantees
that sample gas released by a leak is diluted to such an extent that an explosive gas mixture cannot occur. The volume flow
of the protective gas has therefore been set to 1 l/min; this is more than 100 times the maximum quantity of sample gas
released.
8
Category 4 to EN ISO 13849-1
, or
.
Compact Operating Instructions in accordance with EN 61010-1 and EN 60079-0
,
Category 1 to EN ISO 13849-1
without consideration of system-
EN ISO 13849-1
.
A5E45779389002-01, 09/2018