Siemens SITRANS SL Información Del Producto página 2

Note
When continuous purging is needed, make sure that the needle valve set to its open position. Start the purging process with
the highest permitted pressure at the purge inlet. This decreases the necessary time to purge the sensor heads completely
free of ambient air. When the sensor heads are free from ambient air the purge flow can be reduced to values significantly
below 1 l/min. As long as a small overpressure in the sensor heads remains ambient air will not enter.
Purging with nitrogen on the sensor side is almost always necessary for O
oxygen of the air present in the unit. The volumes in the sensor head are then continuously purged with nitrogen.
Be aware that it is necessary to purge the sensors free of any ambient air every time after sensor purging was disabled.
Section 9.1.1.2
In section 9.1.1.2 - Span verification - the following parts are modified to read as follows:
Purging steps:
Step 3: Purging with Nitrogen
Note
In the instruction it is assumed that totally oxygen free nitrogen is used. The concentration value of the SITRANS SL during
this procedure will not be lower than the oxygen content in the nitrogen.
1. Attach your source of purging gas (N
2. Close the other needle valve.
3. Purge the verification tube until the concentration value falls below 0.05 Vol% O
exceed 1 bar (100 kPa) overpressure compared to ambient pressure. The gas flow should be higher than 1 l/min and the
pressure of the nitrogen between 2 and 5 bar absolute. The gas should be able to escape through the two capillaries on
the receiver and transmitter.
4. Close the needle valve. Wait for 10 minutes. After this time the O
0.15 Vol %. If the O
2
chapter for further proceedings.
5. Wait until there is no more overpressure left in the system.
6. Remove the needle valve completely on either the receiver and transmitter side. This is necessary to avoid any
overpressure in the tube.
7. Fill the verification tube according to one of the two alternatives below.
Step 4b: Filling the verification tube with pressurized air
1. Disconnect the nitrogen source.
2. Attach your source of dry, oil free, pressurized air to the needle valve on either of the receiver or transmitter side and
make sure the pressure at the inlet doesn't exceed an overpressure of 1 bar compared to ambient pressure.
3. Purge with a volume flow of at least 1 liter/minute. Verification must be performed within 10 minutes from this step to
prevent ambient air from entering into the volume behind the lenses.
4. Purge until the concentration value stabilizes (concentration changes less than 0.1 vol %/minute) and then turn off the
gas.
5. Set the manual temperature value in the LUI to the temperature displayed by the thermometer.
2
) to the needle valve on either the receiver or transmitter side.
2
value exceeds this limit refer to section (Problem handling: insufficient purging) at the end of this
applications to avoid an offset caused by the
2
. The nitrogen pressure should not
2
value should not have increased to more than
2
Amendment 2 to Operating Instructions SITRANS SL Version 04
A5E47707441A-01, 07/2019