Setting The Correct Process Side Purging - Mettler Toledo GPro 500 Kurzanleitung Zur Einrichtung

Quick Setup Guide TDL GPro™ 500
Setting the correct
process side purging
The flow rate of the purging will affect the effective path length and conse-
quently the measurement value.
Therefore the following procedure should be used. Start with a very high flow
rate and gradually decrease it. The measurement value will then start at a low
value and increase with decreasing purge flow. At some point it will level out
and stay constant for a while and then again start increasing. Choose a purge
flow in the middle of the constant region.
2
1
Decreasing purge flow
Optimizing the purge flow
On the x-axis there is purge flow and on the y-axis there is the instrument con-
centration reading.
1 Concentration reading with high purge flow. The path length is now shorter
than the effective path length since the purge tubes is completely filled with
purging gas and some of the purging gas is flowing into the measurement
path.
2 Concentration reading with optimized purge flow. The path length is now
equal to the effective path length since the purge tubes are completely filled
with purge gas. See the illustration below.
3 Concentration reading with no purge flow. The path length is now equal to
the nominal path length since the probe is completely filled with process
gas.
4 The optimized purge flow.
Always start purging at maximum flow before starting the process.
Purging must always be switched on in order
to avoid dust deposition onto the optical surfaces.
4
WARNING
WARNING
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