Settings For Tunable Diode Laser (Tdl) Analyzer - Mettler Toledo GPro 500 Guía De Instalación Rápida

Quick Setup Guide TDL GPro 500
3 Settings for Tunable Diode Laser (TDL) Analyzer
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(PATH: H\Config\Measurement\TDL quick setup)
If a TDL analyzer is connected, while during the channel setup Auto has been
chosen, the parameters Pressure, Temperature and Path length can be set or
adjusted. The same para meters will be displayed if during the channel setup
not Auto but TDL has been set.
Press the button for Pressure.
– External: current external pressure value coming from a pressure trans-
ducer of 4 ... 20 mA analog output
– Fixed: p ressure compensation uses a fixed value to be set manually.
Note: if this pressure compensation mode is selected, a con-
siderable gas concentration measurement error resulting from
a non-realistic pressure value can take place.
If External compensation is selected, then the minimum (4 mA) and maxi-
mum (20 mA) analog output signals from the pressure transducer must be
mapped to the corresponding analog input of the TDL. Key in the minimum
and maximum values of the pressure in the following units:
– hPa – mmHg
– psi – kPa
In general, METTLER TOLEDO recommends the use of absolute pressure trans-
ducers for more accurate signal compensation over a broad pressure range.
If, however, small pressure variations around atmospheric pressure are to be
expected, relative pressure sensors will produce better results; but the varia-
tions of the underlying barometric pressure will be ignored.
For relative pressure sensors, the minimum and maximum values must be
mapped so that the TDL can interpret the analog pressure signal as "absolute",
i.e. a fixed barometric pressure of 1013 mbar (for example) has to be added
to the mapped values.
If Fixed compensation is selected, the fixed pressure value with which the
measurement signal will be calculated has to be keyed in manually. For the
fixed pressure, the following units can be used:
– hPa – mmHg
– psi – kPa
– mbar
– mbar