Siemens SITRANS SL Operating Instructions Manual page 24

Description
2.5 Functional description
Purging
The easiest way to avoid condensation and dust deposits on the sensor windows is to purge
them, e.g. with air. Purging must be selected depending on the application. The transmitted-
light sensors can therefore be configured for the respective situation.
The purging gas must not contain any concentrations of the measurement component. The
presence of the gas in the sensor heads or the purging tubes may influence the measured
concentration.
Recommendations for suitable purging and quality requirements of the purging gases can be
obtained from chapter Technical data (Page 181)
①
②
③
④
Figure 2-9
26
Purging tube
Process flange (customer)
Inlet for purging on the process side
Outlet for purging on sensor side
if applicable
Arrangement for purging on the sensor side of the SITRANS SL
⑤
Transmitter or receiver unit: optics tube
⑥
Transmitter or receiver unit: sensor head
⑦
Inlet for purging on sensor side if applicable
⑧
Process interface
Operating Instructions, 12/2010, A5E01132948-04
SITRANS SL