Model 9310 pages

WESTERN RESEARCH

®

PROCESS INSTRUMENTS

Model 931 Single-Gas Analyzer
Benefits
►tNo-moving-parts design
►tMeasurement of additional
species optionally available
t (IR or thermal conductivity)
►tSample return to process (with
HAG probe option)
►tMinimal sample conditioning
►tLow maintenance design
►tMinimal calibration drift
►tStream switching capability

Introduction
The Model 931 is a rugged, singlecomponent photometric gas analyzer
housed in an explosion-proof
package designed for a variety of
gas monitoring and process control
applications. Whether it’s reliable
high concentration H2S analysis
for feed-forward control of modern
SRU plants, monitoring of sour gas
pipelines, or process control of SRU
tail gas treating plants, this single gas
analyzer is the best choice for reliable,
field-proven, and rugged singlespecies measurement applications.
t The Model 931 analyzer system
is available with a heated cell option
to avoid any hydrocarbon or water
condensation. A fully integrated
AMETEK Process Instruments
sample system ensures reliable
dew point control without running
the risk of plugging, contaminating,
or flooding the analyzer. Many
process applications require the
detection of species which do not
absorb ultraviolet light. The model
931 may optionally be incorporated
with IR sensors for the measurement
of hydrocarbons or CO2, and a
thermal conductivity sensor for the
measurement of H2. Model 931
can also be configured for SO2 as
the primary measurement. These
sensors are incorporated with the

UV photometer and utilize the same
proven flow and sample system.
Typical applications include the
measurement of hydrogen and H2S
(and optionally COS and CS2) in
amine-based tail gas treaters, SO2
breakthrough form cobalt molybdate
catalyst beds, as well as other sulfur
recovery plant applications such as
feed forward control by measuring
hydrcarbons, H2S and or carbon
dioxide in acid plant inlet gas.
t No matter what the need is, this
flexible, low-maintenance analyzer
design is the answer to many of
today’s complex process control
requirements.

Benefits of Model 931
The Western Research® Model
931 uses AMETEK’s proprietary
high-resolution UV technology in
a dual-beam, dual-wavelength
configuration and no-moving-parts
design. Instead of using a filter/
chopper wheel to alternate between
measure and reference
wavelengths, the Model
931 uses a fixed optical
configuration and pulsed
UV lamps. This design
leads to increased light
throughput, reduced
noise levels, and reduced
maintenance. The dualbeam configuration,
combined with the
reference measurement,
ensures low noise
performance with minimal
baseline and span drift.

making it possible to configure
this analyzer to measure many
components that absorb UV/VIS
energy. This high resolution design
enables unparalleled linearity over
a wide dynamic range (less than
1% deviation over 3 to 4 orders of
magnitude), which leads to simple,
robust data analysis.
The Model 931 analyzer utilizes
two onboard micro-processors that
provide concentration calculations,
data processing, temperature control,
calibration and sophisticated selfdiagnostics.

Typical Applications
►tAmine-based tail gas treating
t (H2S/COS + optional H2)
►tSRU feed gas analysis
t (H2S + optional HC)
►tWell head gas
►tSour gas pipelines

t Resolution of better
than 0.02nm is achieved
with high-intensity, lowenergy hollow cathode
UV source lamps. These
lamps emit UV radiation
at precise wavelengths,
providing construction of
the UV lamp determines
the wavelength of interest,

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