General Directives For Explosion Protection; Internal Explosion Protection; External Explosion Protection - Siemens SIPROCESS GA700 Compact Operating Instructions

Safety instructions

2.4 General directives for explosion protection

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.
16
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 is permissible only at the type of pro-
tection Ex py!
If an occasionally explosive gas mixture is introduced in OXYMAT 7, each inlet / outlet for sam-
ple gas and reference gas must be equipped with one flame arrester each. The installed flame
arresters have to fulfil the safety-specific requirements of this ignitable gas mixture.
You do not need a flame arrestor at the reference gas input if the following requirements are
met:
You use a non-combustible gas as the reference gas and
•
You have ensured that the reference gas is introduced before the device is switched on and
•
afterwards uninterruptedly.
Do not introduce any frequently or permanently explosive gas mixtures!
A case-by-case assessment is required for these combustible gas mixtures!
Devices in explosion-proof design
Compact Operating Instructions, 05/2018, A5E35134047-03