Internal Explosion Protection; Further Safety Measures; Overview - Siemens SIPROCESS GA700 Compact Operating Instructions

2.5.2

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
Case
Non-combustible sam‐
ple gases and gas mix‐
tures below the lower ex‐
plosive limit (LEL)
Occasionally explosive
sample gases
Gas mixtures which are
frequently or permanent‐
ly explosive
Sample gases above
the upper explosive limit
(UEL)
2.5.3

Further safety measures

2.5.3.1

Overview

The exhaust lines for the sample and reference gases must terminate outside the hazardous
area at a harmless position. The sample gas exhaust line can also be returned to the sampling
point.
When connecting combustible or non-combustible sample gases into the hazardous area, both
the sample gas inlet and outlet must be provided with a flame inhibitor.
The maximum permissible sample gas pressure in the analyzer depends on the type of
connected gas, and is described in the technical specifications under the point "Sample gas
input conditions".
Devices in explosion-proof design
Compact Operating Instructions, 05/2015, A5E35134047-02
Measures
If it has been ensured that the sample gas in the CS always remains below the lower explosive
limit, the need for flame arrestors may be obsolete.
If you have equipped the inputs/outputs for sample gas and reference gas with one flame arrestor
each, you may occasionally introduce explosive sample gases. The flame inhibitors must meet
the safety requirements for the combustible medium.
You do not need a flame arrestor at the reference gas input if the following requirements are met:
● You are using an inert gas as reference gas. Only inert gases are permitted as reference gases.
● You have ensured that reference gas is introduced for the device is switched on.
● The constant monitoring of the reference gas is guaranteed.
Do not introduce any frequently or permanently explosive gas mixtures!
Depends on individual case!
2.5 General directives for explosion protection
Safety instructions
23