General Directives For Explosion Protection; Internal Explosion Protection; External Explosion Protection; Safety Measures For All Types Of Protection - Siemens SIPROCESS GA700 Compact Operating Instructions

2.4

General directives for explosion protection

2.4.1

Internal explosion protection

Internal explosion protection refers to the sample gas path (containment system "CS") in the
analyzer and to the ignition protection of the process gas. A differentiation must be made
between the following cases:
Table 2- 1 Internal explosion protection: Differentiation of cases
Sample gas
Non-combustible gas
mixtures and gas mix-
tures below 25% of the
lower explosive limit
(LEL)
Occasionally explosive
gas mixtures
Gas mixtures which are
frequently or perma-
nently explosive
Gas mixtures above the
upper explosive limit
(UEL)
2.4.2

External explosion protection

The external explosion protection serves to prevent penetration of explosive gas mixtures
(gas vapors) into the enclosure or ignition on the surfaces.
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.
Devices in explosion-proof design
Compact Operating Instructions, 11/2019, A5E35134047-04
Measures
If you have ensured that the sample gas in the CS does not become explosive, flame arresters
are dispensable.
The introduction of an occasionally explosive gas mixture into the wall-mounted device is per-
missible only with the ignition protection type Ex px/py. We recommend an automatic purging
unit in accordance with Ex px.
When introducing a combustible or occasionally explosive gas mixture in OXYMAT 7 into the
wall-mounted device, each inlet/outlet for sample gas and reference gas must be equipped with
a flame arrestor. The installed flame arresters have to fulfil the safety-specific requirements of
this ignitable gas mixture.
Introducing an occasionally explosive gas mixture in OXYMAT 7 into the rack-mounted device is
not permissible.
Do not introduce any frequently or permanently explosive gas mixtures!
A case-by-case assessment is required for these combustible gas mixtures.
2.4 General directives for explosion protection
Safety instructions
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