Endress+Hauser SpectraSensors SS2100r, Руководство по оборудованию

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Introduction
Hardware Manual 1
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7
All SpectraSensors TDL gas analyzers employ the same design and hardware
platform. Measuring different trace gases in various mixed hydrocarbon
background streams is accomplished by selecting a different optimum diode
laser wavelength between 700-3000 nm, which provides the least amount of
sensitivity to background stream variations.
Getting Familiar with the Analyzer
Figure 1–5 shows the front and rear panels of the analyzer. On the front panel,
the keypad and LCD display serve as the user interface to the analyzer. The
pressure regulator sets the maximum pressure for the sample flow. The actual
pressure of the sample flow is displayed by the pressure gauge. The flow rate
is set by a needle valve and monitored via the flow meter. The scrubber
efficiency indicator marks any scrubber breakthrough by a change of color of
the powder in the sight glass.
On the rear panel, power is connected to the analyzer via a power input module
that includes a power switch and a fuse drawer. There are separate D-sub
connections for the serial, 4-20 mA current loop and alarm outputs. Quick-
disconnect fittings are provided for the sample supply and return lines.
Inside the analyzer enclosure, there are two compartments, as shown in Figure
1–6 and Figure 1–7.
The left compartment contains the control electronics, input/output
connections and sample conditioning components. The right compartment
contains the measurement cell and is temperature controlled with a heater and
recirculating fan.
A set of solenoid switching valves connected to the analyzer control electronics
in the left compartment direct the flow either directly (wet cycle) to the
analyzer, or through a scrubber (dry cycle) and on to the analyzer. The reason
for the two flow paths is that the analyte spectrum overlaps a strong resonance
of one or more components of the background gas, which causes interference
in the measurement. For example, when the analyzer detects a change in the
background signal, the flow is sent through the scrubber for a measurement of
the flow devoid of analyte (the analyzer automatically switches back and forth
between the two streams as required). This measurement yields the amount
of signal attributable to the background gases. Subtracting this background
contribution from the normal measurement results in a signal that is
proportional only to the desired analyte concentration.