1-4 | Model 933S UV Analyzer
About the Analyzer Sample System
The sample system is mounted to the Model 933S Analyzer backpan. The
purpose of the system is to maintain constant pressure and temperature,
and to condition the sample to obtain correct analysis.
The sample system consists of (see Figures 1-2 and 1-3):
Component Function
Sample Probe Extends into the sample stream to obtain a representative sample.
Contains a shut-o valve used to isolate the analyzer’s sample system
from the sample stream.
Pressure Regulator The pressure regulator adjusts the sample gas pressure to the ana-
lyzer operating pressure (typically 80 PSIG/560 KPAG) if the process
pressure is higher than the analyzer operating pressure (refer to Final
“As-Built” drawings in the analyzer Documentation Package).
Pressure Gauge The pressure gauge is used to set the proper sample pressure in the
sample system.
Solenoid Block The solenoid manifold block directs ow between the Zero, Column A,
and Column B solenoids. There is also a pressure relief valve to safe-
guard against over pressuring of any components down stream of the
Solenoid Block or if the pressure regulator fails. This valve is factory-
adjusted to open at approximately 150 PSIG (1050 KPAG).
Column Switching Solenoids Solenoids are automatically turned on or o to initiate switching the
sample gas between columns.
Zero Solenoid The zero solenoid allows Zero gas (or Span gas) to ush the sample
system during the Auto-Zero (or Span) process. The column switching
solenoids are closed when the zero solenoid is open.
Column Block The Column Block is where the sample conditioning process takes
place. The Column Block incorporates a proprietary material to permit
correct sample analysis.
Heat Exchanger Block The Heat Exchanger Block reduces the temperature of the conditioned
gas sample prior to it entering the Measuring Cell.
Measuring Cell The Measuring Cell is a chamber of known length, with optical-grade
quartz windows, through which the radiation beam passes through the
gas sample. The windows are sealed by means of o-rings and remov-
able end caps.
The Measuring Cell can be unheated (typical) or heated (optional) to
keep the sample gas above the dewpoint. Other variations of Measur-
ing Cells are also available.
Flow Indicator The ow meter provides a visual indication of the sample ow rate in
liters/minute through the analyzer. Note that the scaling on the ow
indicator is for air at standard temperature and pressure. Its purpose is
to indicate and ensure that appropriate ow conditions are maintained
and not to provide an absolute measure of the ow of sample gas.
Some systems use a Rotameter instead of the Flow Indicator.
Filterblock Assembly (optional)
The Filterblock Assembly removes condensables and particulates from
the sample gas.
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