Purging - Siemens LDS 6 Operating Instructions Manual

Installation Guidelines
ATEX manual for LDS 6
A5E01206710-02
AD_4100-2080_Transmitter_Ex_Std_CD6 and AD_4100-
2081_Receiver_Ex_Std_CD6 in Chapter 4 show the transmitter
and receiver sensors. All ATEX devices are labelled.

2.2.3 Purging

Purging can be divided into purging of optical process interfaces
and purging of sensors.
Purging of Optical Process Interface
Wedge optics can be purged with instrument air, elevated instru-
ment air, air blower or steam.
Always install the purging before the sensors are installed to
avoid damage to the optics during the rest of the installation pro-
cess. Figure 2.7 on the next page shows the principle set-up for
purging. For optimal performance use sensors equipped for the
specific purging type, supplied from Siemens Laser Analytics.
Sensor Purging
In oxygen applications it might be necessary to purge boxes and
lens tubes with an oxygen free gas, such as nitrogen. Any oxygen
free gas can be used for this purpose. However, when explosive
gases are used the Ex sensor must be used. Purging with oxygen
free gas is also necessary when performing water vapor mea-
surements. The sensors for sensor purging supplied by Siemens
Laser Analytics include a needle valve and a check valve (see fig-
ure 2.7).
Instructions for purging set-up installation are given in the fol-
lowing section.
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