Spectrasensors SS2100 Instruction Manual

SS2100 H2S Analyzer
Hardware Installation and Maintenance
Manual
Hardware Installation and Maintenance
Manual
P/N 4900002218 rev C
SS2100 H2S Analyzer
Hardware Installation
and Maintenance Manual

Products of
4333 W Sam Houston Pkwy N, Suite 100
Houston, TX 77043-1223
Tel: [phone]
Fax: [phone]
www.spectrasensors.com
Copyright © 2015 SpectraSensors, Inc. No part of this manual may be reproduced in
whole or in part without the express written permission of SpectraSensors, Inc.
SpectraSensors reserves the right to change product design and specifications at any
time without prior notice.
SS2100 H2S Analyzer
Hardware Installation and
Maintenance Manual
Use this manual with the
FS Firmware Operator’s Manual

Revision History
Revision Engineering Order Date
A EO15800 4/17/14
B ECR16037 3/6/15
C ECR16349 11/6/15

Hardware Installation and Maintenance Manual i
TABLE OF CONTENTS
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v
1: Introduction
Who Should Read This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
How to Use This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
General Warnings and Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Equipment Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Instructional Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Conventions Used in this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
SpectraSensors Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
About the Gas Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Sample Conditioning System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Determining Firmware Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
How the Analyzers Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Differential TDLAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Wavelength Modulation Spectroscopy (WMS) Signal Detection . . . . . . . . . . . 1-6
Getting Familiar with the Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
2: Installation
What Should be Included in the Shipping Box . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Inspecting the Analyzer and SCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Installing the Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Hardware and Tools for Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Hardware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Mounting the Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Lifting/carrying the analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
To mount the analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Connecting Electrical Power to the Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Protective chassis and ground connections . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
To connect electrical power to the H2S analyzer . . . . . . . . . . . . . . . . . . . . . 2-5
Field Interface Loads (Solenoid Valves) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Connecting Electrical Power to the Enclosure Heater . . . . . . . . . . . . . . . . . . . . . 2-8
To connect electrical power to the enclosure heater . . . . . . . . . . . . . . . . . . . 2-8
Application of Conduit Lubricant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Connecting the Output Signals and Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
To connect the H2S analyzer signal and alarm cables . . . . . . . . . . . . . . . . . 2-11
Changing the 4-20 mA Current Loop Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
To change the 4-20 mA board from source to sink . . . . . . . . . . . . . . . . . . . 2-14
Calibrating the analog output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
Testing and adjusting the 4-20 mA zero and span . . . . . . . . . . . . . . . . 2-15
Connecting the Gas Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
Instrument air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
To connect the sample supply line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
To connect the sample return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17
To connect the bypass return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18
Conditioning the SCS Tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
3: Sample Conditioning System
About the SCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Checking the SCS Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
To perform SCS installation checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

SS2100 H2S Analyzer
ii 4900002218 rev. C 11-6-15
Starting up the SCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
To prepare for SCS startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
To start up the sample system heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
To start up the field pressure reducing station. . . . . . . . . . . . . . . . . . . . . . . 3-5
To start up the sample bypass stream on process sample . . . . . . . . . . . . . . . 3-5
To start up the analyzer on process sample . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Shutting Down the SCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
To isolate the measurement cell for short-term shutdown. . . . . . . . . . . . . . . 3-8
To isolate the SCS for short-term shutdown . . . . . . . . . . . . . . . . . . . . . . . . 3-8
To isolate the process sample tap for long-term shutdown . . . . . . . . . . . . . . 3-9
To purge the analyzer for shipment/relocation. . . . . . . . . . . . . . . . . . . . . . 3-10
Heat Trace Bundle Sleeve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Appendix A: Specifications
Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-16
Appendix B: Maintenance and Troubleshooting
Gas Leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
To keep the sampling lines clean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2
Excessive Sampling Gas Temperatures and Pressures . . . . . . . . . . . . . . . . . . . . B-2
Electrical Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3
Potential Risks Affecting Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3
Mitigating risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3
Exposure to process gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3
Exposure to toxic gas (H2S). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3
Electrocution hazard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4
Explosion hazard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4
Relief Valve Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4
Peak Tracking Reset Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4
Cleaning the Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-5
Tools and supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-5
To clean the mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-6
Replacing the Membrane Separator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-7
Replacing the Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-8
Replacing the Pressure Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-8
Tools and materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-9
To replace the pressure sensor:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-9
Periodic SCS Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-14
Preventive and On-Demand SCS Maintenance . . . . . . . . . . . . . . . . . . . . . . . . B-15
Regular SCS Status Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-15
To check filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-16
Servicing the H2S Scrubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-16
To replace the scrubber and scrubber efficiency indicator . . . . . . . . . . . . . . B-19
Disposal of Used Scrubbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-20
Instrument Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-20
Service Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-25
Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-25
Return Material Authorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-25
Packing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-25
To prepare the analyzer for shipment or storage . . . . . . . . . . . . . . . . . . . . B-26
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-27
Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-27
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-27
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index-1

Hardware Installation and Maintenance Manual iii
LIST OF FIGURES
Figure 1–1. Schematic of a typical laser diode absorption spectrometer . . . . . . 1-4
Figure 1–2. Typical raw signal from a laser diode absorption spectrometer
with and without mirror contamination . . . . . . . . . . . . . . . . . . . . 1-5
Figure 1–3. Typical normalized absorption signal from a laser diode
absorption spectrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Figure 1–4. Typical normalized 2f signal; species
concentration is proportional to the peak height . . . . . . . . . . . . . . 1-7
Figure 1–5. SS2100 analyzer architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Figure 1–6. H2S analyzer electronics control
board (AC) showing signal terminal block and alarm relays . . . . . . 1-9
Figure 1–7. H2S analyzer electronics control board (DC) showing
signal terminal block and alarm relays. . . . . . . . . . . . . . . . . . . . 1-10
Figure 2–1. Lifting points for the SS2100 H2S analyzer . . . . . . . . . . . . . . . . . 2-3
Figure 2–2. AC single phase (120 VAC or 240 VAC) connection
terminal block in analyzer electronics enclosure . . . . . . . . . . . . . . 2-7
Figure 2–3. AC connection terminal block for 120 VAC enclosure heater . . . . . . 2-8
Figure 2–4. Applying conduit lubricant . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
Figure 2–5. H2S analyzer mating terminal block (TB2) for connecting
signal cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Figure 2–6. Analyzer 4-20 mA board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
Figure A–1. Outline and mounting dimensions (front view) of
SS2100 for H2S analyzer (fixed mount, conventional) . . . . . . . . . . A-3
Figure A–2. SCS schematic of SS2100 for H2S analyzer
(fixed mount, conventional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4
Figure A–3. SCS schematic - Bill of Materials (fixed mount, conventional). . . . . A-5
Figure A–4. SCS schematic - solenoid/air-
actuated valves (fixed mount, conventional) . . . . . . . . . . . . . . . . A-6
Figure A–5. SCS schematic -Air-actuated valve, Liquid knock-
out (fixed mount, conventional) . . . . . . . . . . . . . . . . . . . . . . . . . A-7
Figure A–6. SCS schematic - high H2S purge (fixed mount, conventional) . . . . A-8
Figure A–7. Power and signal wiring diagram (fixed mount, conventional) . . . . A-9
Figure A–8. Wiring diagram - optional air actuated
valve (fixed mount, conventional). . . . . . . . . . . . . . . . . . . . . . . A-10
Figure A–9. Outline and mounting dimensions - optional heat trace /
high H2S purge (fixed mount, conventional) . . . . . . . . . . . . . . . A-11
Figure A–10. Outline and mounting dimensions (fixed mount, modular) . . . . . . A-12
Figure A–11. SCS schematic - optional heat trace and heater power
(fixed mount, modular) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-13
Figure A–12. SCS schematic - optional one-point solenoid validation
(fixed mount, modular) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-14
Figure A–13. Power and signal wiring (fixed mount, modular) . . . . . . . . . . . . . A-15

SS2100 H2S Analyzer
iv 4900002218 rev. C 11-6-15
Figure B–1. SCS cabinet interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-10
Figure B–2. Removed measurement cell with pressure sensor face up . . . . . . B-10
Figure B–3. Removing the old pressure sensor . . . . . . . . . . . . . . . . . . . . . . B-11
Figure B–4. Removing excess seal tape from flange . . . . . . . . . . . . . . . . . . . B-11
Figure B–5. Removing excess seal tape from inside cell . . . . . . . . . . . . . . . . B-12
Figure B–6. Replacing seal tape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-12
Figure B–7. Replacing pressure sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-13
Figure B–8. New pressure sensor installed . . . . . . . . . . . . . . . . . . . . . . . . . B-13
Figure B–9. Predicted scrubber lifetime based on average H2S load . . . . . . . . B-17
Figure B–10. Scrubber and scrubber efficiency indicator . . . . . . . . . . . . . . . . . B-17
Figure B–11. H2S scrubber efficiency indicator before and
after breakthrough . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-18

Hardware Installation and Maintenance Manual v
LIST OF TABLES
Table 1–1. Fuse specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11
Table 2–1. H2S analyzer input/output signal connections. . . . . . . . . . . . . . . 2-13
Table A–1. SS2100 H2S analyzer specifications . . . . . . . . . . . . . . . . . . . . . . A-1
Table A–2. Replacement parts for H2S analyzer . . . . . . . . . . . . . . . . . . . . . A-16
Table B–1. Potential instrument problems and their solutions. . . . . . . . . . . . B-20

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Hardware Installation and Maintenance Manual 1–1
1 - INTRODUCTION
SpectraSensors’ SS2100 products are high-speed, diode-laser based extractive
analyzers designed for extremely reliable monitoring of very low (trace) to
standard concentrations of specific components in various background gases.
In order to ensure that the analyzer performs as specified, it is important to
closely review the installation and operation sections of this manual. This
manual contains a comprehensive overview of the SS2100 hardware
installation and maintenance through step-by-step instructions on:
•Inspecting the analyzer and sample conditioning system (SCS)
•Mounting and connecting the analyzer and SCS
•Maintaining and troubleshooting the system
For instruction on operating the analyzer through firmware programming,
please consult the Firmware Operator’s Manual.
Who Should Read This Manual
This manual should be read and referenced by anyone installing, operating or
having direct contact with the analyzer.
How to Use This Manual
Take a moment to familiarize yourself with this manual by reading the Table
of Contents.
There are a number of options and accessories available for the SS2100. This
manual has been written to address the most common options and accessories.
Images, tables and charts have been included to provide a visual
understanding of the analyzers and its functions. Special symbols are also used
to provide the user with key information regarding the system configuration
and/or operation. Pay close attention to this information.
General Warnings and Cautions
Instructional icons are provided in this manual and on the SS2100 unit to alert
the user of potential hazards, important information and valuable tips.
Following are the symbols and associated warning and caution types to observe
when servicing the analyzer. Some of these symbols are provided for
instructional purposes only and are not labeled on the system.

SS2100 H2S Analyzer
1–2 4900002218 rev. C 11-6-15
Equipment Labels
Instructional Symbols
Warning statement for hazardous voltage. Contact may cause
electric shock or burn. Turn off and lock out system before
servicing.
INVISIBLE LASER RADIATION - Avoid exposure to beam.
Class 3b Radiation Product. Refer servicing to the manufacturer-
qualified personnel.
Failure to follow all directions may result in damage or
malfunction of the analyzer.
INVISIBLE LASER RADIATION - Avoid
exposure to beam. Class 3b Radiation Product.
Refer servicing to the manufacturer-qualified
personnel.
General notes and important information concerning the
installation and operation of the analyzer.
Failure to follow all directions may result in damage or
malfunction of the analyzer.
Failure to follow all directions or substitution of components may
result in explosion.
Failure to follow all directions may result in fire.
Maximum voltage and current specifications for fuses.
LASER RADIATION
AVOID EXPOSURE TO BEAM
CLASS 3B LASER PRODUCT

Introduction
Hardware Installation and Maintenance Manual 1–3
Conventions Used in this Manual
In addition to the symbols and instructional information, this manual is created
with “hot links” to enable the user to quickly navigate between different
sections within the manual. These links include table, figure and section
references and are identified by a pointing finger cursor when rolling over
the text. Simply click on the link to navigate to the associated reference.
SpectraSensors Overview
SpectraSensors, Inc. is a leading manufacturer of technologically advanced
electro-optic gas analyzers for the industrial process, gas distribution and
environmental monitoring markets. Headquartered in Houston, Texas,
SpectraSensors was incorporated in 1999 as a spin-off of the NASA/Caltech Jet
Propulsion Laboratory (JPL) for the purpose of commercializing space-proven
measurement technologies initially developed at JPL.
About the Gas Analyzers
The SS2100 includes tunable diode laser (TDL) absorption spectrometers
operating in the near- to short-wavelength infrared. Each compact sensor
consists of a TDL light source, sample cell and detector specifically configured
to enable high sensitivity measurement of a particular component within the
presences of other gas phase constituents in the stream. The sensor is
controlled by microprocessor-based electronics with embedded software that
incorporates advanced operational and data processing algorithms.
Sample Conditioning System
A sample conditioning system (SCS) has also been included with the analyzer.
The SCS has been specifically designed to deliver an optimum sample stream
that is representative of the process systems stream at the time of sampling.
Most SS2100s are configured for use at extractive natural gas sampling
stations.
Determining Firmware Version
When the analyzer is powered on for the first time, the firmware version will
display on the system LCD for approximately seven seconds. Refer to
“Powering Up the Analyzer” in the Firmware Manual for this analyzer for
operational instructions. The firmware version for each analyzer is also listed
on the analyzer calibration certificate.
How the Analyzers Work
The SS2100 employs tunable diode laser absorption spectroscopy (TDLAS) to
detect the presence of trace substances in process gases. Absorption
spectroscopy is a widely used technique for sensitive trace species detection.

SS2100 H2S Analyzer
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Because the measurement is made in the volume of the gas, the response is
much faster, more accurate and significantly more reliable than traditional
surface-based sensors that are subject to surface contamination.
In its simplest form, a diode laser absorption spectrometer typically consists of
a sample cell with a mirror at one end, and a mirror or window at the opposite
end, through which the laser beam can pass. Refer to Figure 1–1. The laser
beam enters the cell and reflects off the mirror(s) making multiple passes
through the sample gas and eventually exiting the cell where the remaining
beam intensity is measured by a detector. With the SS2100, sample gas flows
continuously through the sample cell ensuring that the sample is always
representative of the flow in the main pipe.
Figure 1–1 Schematic of a typical laser diode absorption
spectrometer
Due to their inherent structure, the molecules in the sample gas each have
characteristic natural frequencies (or resonances). When the output of the
laser is tuned to one of those natural frequencies, the molecules with that
particular resonance will absorb energy from the incident beam. That is, as the
beam of incident intensity, I0(),passes through the sample, attenuation occurs
via absorption by the trace gas with absorption cross section (). According
to the Beer-Lambert absorption law, the intensity remaining, I(), as measured
by the detector at the end of the beam path of length / (cell length x number
of passes), is given by
, (1)
OPTICAL HEAD
DETECTOR
WINDOW
OUTLET
TEC
LASER
INLET
PRESSURE
SENSOR
FAR MIRROR
I
 I0exp lN–=

Introduction
Hardware Installation and Maintenance Manual 1–5
where Nrepresents the species concentration. Thus, the ratio of the absorption
measured when the laser is tuned on-resonance versus off-resonance is
directly proportional to the number of molecules of that particular species in
the beam path, or
. (2)
Figure 1–2 shows the typical raw data (in arbitrary units [u.a.]) from a laser
absorption spectrometer scan including the incident laser intensity, I0(),and
the transmitted intensity, I(), for a clean system and one with contaminated
mirrors (shown to illustrate the system’s relative intensity to mirror
contamination). The positive slope of raw data results from ramping the current
to tune the laser, which not only increases the wavelength with current, but
also causes the corresponding output power to increase. By normalizing the
signal by the incident intensity, any laser output fluctuations are canceled, and
a typical, yet more pronounced, absorption profile results. Refer to Figure 1–3.
Figure 1–2 Typical raw signal from a laser diode
absorption spectrometer with and without mirror
contamination
N
1–
l
--------------I
I0
--------------ln=
3.0
2.5
2.0
1.5
1.0
0.5
Incident Energy I0()
Raw Signal, I()
Raw Signal, I()
(Contaminated Mirrors)
Wavelength [a.u.]
Signal [a.u.]
0.0

SS2100 H2S Analyzer
1–6 4900002218 rev. C 11-6-15
Figure 1–3 Typical normalized absorption signal from
a laser diode absorption spectrometer
Note that contamination of the mirrors results solely in lower overall signal.
However, by tuning the laser off-resonance as well as on-resonance and
normalizing the data, the technique self calibrates every scan resulting in
measurements that are unaffected by mirror contamination.
Differential TDLAS
Similar to TDLAS, this SpectraSensors technology involves subtracting two
spectrums from one another. A “dry” spectrum, a response from the sample
when the analyte of interest has been completely removed, is subtracted from
the “wet” spectrum, a response from the sample when the analyte is present.
The remainder is a spectrum of the pure analyte. This technology is used for
very low or trace measurements and is also useful when the background matrix
changes over time. Refer to http://www.spectrasensors.com/spectral-
subtraction-in-tdlas-analysis/ for more information.
Wavelength Modulation Spectroscopy (WMS) Signal Detection
SpectraSensors takes the fundamental absorption spectroscopy concept a step
further by using a sophisticated signal detection technique called wavelength
modulation spectroscopy (WMS). When employing WMS, the laser drive
current is modulated with a kHz sine wave as the laser is rapidly tuned. A lock-
in amplifier is then used to detect the harmonic component of the signal that
is at twice the modulation frequency (2f), as shown in Figure 1–4. This phase-
sensitive detection enables the filtering of low-frequency noise caused by
turbulence in the sample gas, temperature and/or pressure fluctuations, low-
frequency noise in the laser beam or thermal noise in the detector.
1.0
0.99
0.98
0.97
0.96
0.95
Normalized Absorption Signal
Wavelength [a.u.]
Signal [a.u.]

Introduction
Hardware Installation and Maintenance Manual 1–7
Figure 1–4 Typical normalized 2f signal; species
concentration is proportional to the peak height
With the resulting low-noise signal and use of fast post-processing algorithms,
reliable parts per million (ppm) or parts per billion (ppb) detection levels are
possible (depending on target and background species) at real-time response
rates (on the order of 1 second).
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 700-3000nm, which provides the least amount of
sensitivity to background stream variations.
Getting Familiar with the Analyzer
Figure 1–5 shows a sample SS2100 H2S analyzer from a front view. The
analyzer is typically comprised of two main enclosures; the analyzer electronics
and the Sample Conditioning System (SCS). On the front panel of the analyzer
electronics, the keypad and LCD serve as the user interface to the analyzer.
Some systems may also have a keypad cover. The analyzer control electronics
drive the laser, collect the signal, analyze the spectra and provide
measurement output signals.
Housed inside the SCS are the measurement cell and heater along with flow
devices to control flow and pressure for the measurement cell and the bypass
loop.
Power is connected to the analyzer from a 120 VAC or 240 VAC power source, as
shown on Figure 1–5. Sample supply/return and instrument air are connected
on the opposite side of the enclosure.
Normalized
2fSignal
Wavelength [a.u.]
Signal [a.u.]

SS2100 H2S Analyzer
1–8 4900002218 rev. C 11-6-15
Inside the analyzer electronics enclosure is the electronics assembly, as shown
in Figure 1–6 and Figure 1–7.
Fuses are located on the electronics control board, as shown in Figure 1–6 and
Figure 1–7. The spare part kits for fuses is shown in Table 1–1.
Figure 1–5 SS2100 analyzer architecture
KEYPAD, LCD
AND KEYPAD
COVER
ANALYZER
ELECTRONICS
ENCLOSURE
SCS
ENCLOSURE
POWER
CONNECTIONS
SAMPLE SUPPLY
CELL OUTLET
(TO ATMOSPHERE)
RELIEF VENT
TEMPERATURE
INDICATOR
SAMPLE BYPASS
(TO ATMOSPHERE)
MOUNTING
FRAME
PROTECTIVE
GROUND
CHASSIS
GROUND

Introduction
Hardware Installation and Maintenance Manual 1–9
Figure 1–6 H2S analyzer electronics control
board (AC) showing signal terminal block and alarm relays
TERMINAL BLOCK (TB2),
OUTPUT SIGNALS
FUSE (F1)
RELAY DRIVER &
4-20mA CONTROL
BOARD STACK
ASSIGNABLE ALARM
GENERAL FAULT
ALARM
COMMON
NO
NC
FUSE (F2)
ALARM/SIGNAL
RELAYS
TERMINAL
BLOCK (TB3),
INTERNAL
PRESSURE/
TEMPERATURE
POWER
SUPPLY
HYTEK
TEMPERATURE
CONTOLLER
BACKPLANE
ARM9 CONTROL
BOARD STACK
CUSTOMER
GROUND
NOTE: Refer to “Spare Parts” on page A-16 for part numbers.
COMPONENT
GROUND
PROTECTIVE
GROUND

SS2100 H2S Analyzer
1–10 4900002218 rev. C 11-6-15
Figure 1–7 H2S analyzer electronics control
board (DC) showing signal terminal block and alarm relays
FUSE (F1)
RELAY DRIVER &
4-20mA CONTROL
BOARD STACK
FUSE (F2)
TERMINAL BLOCK TB2,
OUTPUT SIGNALS
NOTE: Refer to “Spare Parts” on page A-16 for part numbers.
COMMON
NO
NC
ASSIGNABLE ALARM
GENERAL FAULT
ALARM
CUSTOMER
GROUND
POWER
SUPPLY
BACKPLAN
ARM9 CONTROL
BOARD STACK
COMPONENT
GROUND
HYTEK
TEMPERATURE
CONTOLLER
TERMINAL
BLOCK (TB3),
INTERNAL
PRESSURE/
TEMPERATURE
ALARM/SIGNAL
RELAYS
PROTECTIVE
GROUND