SICK EuroFID, Руководство по эксплуатации

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Product Description
EuroFID · Operating Instructions · 8011094 V2.3 · © SICK AG 21
Ejector pump
For transporting the sample gas the EuroFID uses a patented jet pump, referred to in these
instructions as an “ejector pump”. The ejector pump does not have any mechanical,
moving parts and uses a part of the instrument air as induction air.
The sample gas is diluted with the instrument air in the ejector pump. The dilution ratio is
variable and depends on three pressure parameters of the ejector pump. These pressure
parameters are constantly measured and used for a correction calculation which
compensates for the variability of the dilution ratio.
The pressure parameters are also used to automatically monitor the function of the
measuring system (sample gas volume flow, condition of the sample gas filter, plausibility
of the measured values).
Sample gas volume flow (to the detector)
The internal sample gas system comprises a sample gas capillary, a bypass gas capillary
and a pressure controller. The pressure upstream from the sample gas capillary is kept
constant to ensure that the volume flow through the sample gas capillary is constant. To
this purpose control air is added to the bypass flow downstream from the ejector pump
with the aid of a pressure regulator. To this purpose the pressure upstream from the bypass
capillary is kept constant.
FID
The permanent FID flame is supplied with combustion air and fuel gas. Part of the
instrument air serves as combustion air. H
2
or an H
2
/He mixture is used as fuel gas
( → P. 32, §3.3.4 ). The volume flow of the fuel gas is kept constant by a system comprising a
pressure regulator and a flow controller.
Supply of calibration gases
An internal solenoid value is provided for the supply of both zero gas and span gas during
calibration.
The respective calibration gas is routed into the installed sample gas filter; pressure and
volume flow are dimensioned so that the calibration gas completely displaces the sample
gas. The excess calibration gas is discharged through the sample gas inlet. The ejector
pump draws the calibration gas out of the sample gas filter.
●
The induction air is pre-heated in the sensor block. This prevents
condensation of elements of the sample gas in the ejector pump.
●
The sample gas is diluted before it is supplied to the FID as the ejector
pump is installed upstream from the FID. This reduces the effect of
damaging sample gas elements.
If a malfunction occurs during operation which makes operation impossible,
the EuroFID switches the fuel gas off internally. The instrument air remains
switched on for several minutes to flush the sample gas out of the measuring
system.
The internal volume flows of each analyzer unit are optimized individually at
the manufacturer's works.