SICK EuroFID, Руководство по эксплуатации

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34 EuroFID · Operating Instructions · 8011094 V2.3 · © SICK AG
Project Planning
3.5
Sample gas supply
Only applies for the analyzer unit types “wall housing” and “19" slide-in enclosure”.
3.5.1
Correct sample gas supply
Correct selection of the sampling point
If the sample gas is taken from pipes with a large pipe diameter or volumes, the sample
gas should be homogeneously mixed at the sampling point, otherwise the measured
values do not represent the actual gas concentration.

If an inhomogeneous gas distribution is to be expected: Determine the most favorable
sampling point during trials (gauge the pipe diameter).
Prevent condensation
No condensation should occur in the sample gas line. Condensation can corrupt the
measurement result and the condensate can obstruct the sample gas line and gas filter. If
condensate penetrates the measuring system, failure of the analyzer unit can result.
Prevent absorption effects
With some applications it is possible that the material of the sample gas line absorbs or
adsorbs certain gas components. At high gas concentrations the material absorbs a
certain quantity of the gas components and releases these at low gas concentrations into
the sample gas once more.
This results in entrainment of the changes in concentration, which results in an apparent
increase in the reaction time (T90) of the gas analyzer. The narrower the measuring range,
the greater the effect. This effect is minimized by increasing the temperature.

To prevent absorption effects: Use a heated sample gas line.

For sensitive measuring ranges: Select a sample gas line made fully of non-corrosive
steel and heat the pipe.
Install an upstream dust filter (if necessary)
The EuroFID has an integrated sample gas filter. However, the maintenance intervals of the
device can become short if the sample gas contains large quantities of dust.

If the sample gas contains large quantities of dust (recommendation): Install an
external dust filter in the sample gas supply line (preliminary filter, coarse filter).
The gas analyzer is normally part of a measurement system. To ensure trouble-
free and low maintenance operation with accurate measurement results, it is
necessary to configure the measurement system effectively. For example, the
correct choice of the gas sampling point, the devices for sample gas supply
and a careful installation is decisive for the success of the measurement in the
same manner as the analyzer itself. Each application requires an individual
measurement system configuration.

Recommendation: The sample gas supply must be planned and installed
by skilled persons who are familiar with the requirements of FID technology.
Protection against condensation in the sample gas line → P. 35, §3.5.2
The longer the sample gas line, the greater the response delay.

Take the response delay into account during gas transport.

Check whether the response time is sufficiently short, especially for safety-
relevant applications (e.g. as gas detector).
If the sample gas contains condensing elements, the external dust filter must
be heated.