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.
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
Devices in explosion-proof design
Compact Operating Instructions, 01/2022, A5E35134047-11
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 permis‐
sible 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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