Rosemount Manual: Model 500 Gas Chromatograph Hardware Reference Rev K | Rosemount Manuals & Guides
Model 500
Gas Chromatograph
Hardware Reference Manual
Part Number 3-9000-537
Revision K
JULY 2010
Model 500 Gas Chromatograph
System Reference Manual
NOTICE
ROSEMOUNT (“SELLER”) SHALL NOT BE LIABLE FOR TECHNICAL OR EDITORIAL ERRORS IN
THIS MANUAL OR OMISSIONS FROM THIS MANUAL. SELLER MAKES NO WARRANTIES,
EXPRESSED OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE WITH RESPECT TO THIS MANUAL AND, IN NO EVENT,
SHALL SELLER BE LIABLE FOR ANY SPECIAL OR CONSEQUENTIAL DAMAGES INCLUDING,
BUT NOT LIMITED TO, LOSS OF PRODUCTION, LOSS OF PROFITS, ETC.
PRODUCT NAMES USED HEREIN ARE FOR MANUFACTURER OR SUPPLIER IDENTIFICATION
ONLY AND MAY BE TRADEMARKS/REGISTERED TRADEMARKS OF THESE COMPANIES.
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ARE NOT TO BE CONSTRUED AS WARRANTIES OR GUARANTEES, EXPRESSED OR IMPLIED,
REGARDING THE PRODUCTS OR SERVICES DESCRIBED HEREIN OR THEIR USE OR
APPLICABILITY. WE RESERVE THE RIGHT TO MODIFY OR IMPROVE THE DESIGNS OR
SPECIFICATIONS OF SUCH PRODUCTS AT ANY TIME.
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THE ROSEMOUNT LOGO IS A REGISTERED TRADEMARK OF ROSEMOUNT, INC. THE
EMERSON LOGO IS A TRADEMARK AND SERVICE MARK OF EMERSON ELECTRIC CO.
COPYRIGHT
All rights reserved. No part of this work may be reproduced or copied in any form or by any
means - graphic, electronic, or mechanical — without first receiving the written permission of
Rosemount, Inc. Shakopee, MN. U.S.A.
©
2010 BY Rosemount, HOUSTON, TX U.S.A.
WARRANTY
1. LIMITED WARRANTY: Subject to the limitations contained in Section 2 herein and except as
otherwise expressly provided herein, Rosemount, (“Seller”) warrants that the firmware will
execute the programming instructions provided by Seller, and that the Goods manufactured or
Services provided by Seller will be free from defects in materials or workmanship under
normal use and care until the expiration of the applicable warranty period. Goods are
warranted for twelve (12) months from the date of initial installation or eighteen (18) months
from the date of shipment by Seller, whichever period expires first. Consumables and Services
are warranted for a period of 90 days from the date of shipment or completion of the Services.
Products purchased by Seller from a third party for resale to Buyer ("Resale Products") shall
carry only the warranty extended by the original manufacturer. Buyer agrees that Seller has no
liability for Resale Products beyond making a reasonable commercial effort to arrange for
procurement and shipping of the Resale Products. If Buyer discovers any warranty defects and
notifies Seller thereof in writing during the applicable warranty period, Seller shall, at its option,
promptly correct any errors that are found by Seller in the firmware or Services, or repair or
replace F.O.B. point of manufacture that portion of the Goods or firmware found by Seller to
be defective, or refund the purchase price of the defective portion of the Goods/Services. All
replacements or repairs necessitated by inadequate maintenance, normal wear and
usage, unsuitable power sources, unsuitable environmental conditions, accident, misuse,
improper installation, modification, repair, storage or handling, or any other cause not the fault
of Seller are not covered by this limited warranty, and shall be at Buyer's expense. Seller shall
not be obligated to pay any costs or charges incurred by Buyer or any other party except as
may be agreed upon in writing in advance by an authorized Seller rep-resentative. All costs of
dismantling, reinstallation and freight and the time and expenses of Seller's personnel for site
travel and diagnosis under this warranty clause shall be borne by Buyer unless accepted in
writing by Seller. Goods repaired and parts replaced during the warranty period shall be in
warranty for the remainder of the original warranty period or ninety (90) days, whichever is
longer. This limited warranty is the only warranty made by Seller and can be amended
only in a writing signed by an authorized representative of Seller. Except as otherwise expressly
provided in the Agreement, THERE ARE NO REPRESENTATIONS OR WARRANTIES OF ANY
KIND, EXPRESSED OR IMPLIED, AS TO MERCHANTABILITY, FITNESS FOR PARTICULAR
PURPOSE, OR ANY OTHER MATTER WITH RESPECT TO ANY OF THE GOODS OR SERVICES. It
is understood that corrosion or erosion of materials is not covered by our guarantee.
2. LIMITATION OF REMEDY AND LIABILITY: SELLER SHALL NOT BE LIABLE FOR DAMAGES
CAUSED BY DELAY IN PERFORMANCE. THE SOLE AND EXCLUSIVE REMEDY FOR BREACH OF
WARRANTY HEREUNDER SHALL BE LIMITED TO REPAIR, CORRECTION, REPLACEMENT OR
REFUND OF PURCHASE PRICE UNDER THE LIMITED WARRANTY CLAUSE IN SECTION 1
HEREIN. IN NO EVENT, REGARDLESS OF THE FORM OF THE CLAIM OR CAUSE OF ACTION
(WHETHER BASED IN CONTRACT, INFRINGEMENT, NEGLIGENCE, STRICT LIABILITY, OTHER
TORT OR OTHERWISE), SHALL SELLER'S LIABILITY TO BUYER AND/OR ITS CUSTOMERS
EXCEED THE PRICE TO BUYER OF THE SPECIFIC GOODS MANUFACTURED OR SERVICES
PROVIDED BY SELLER GIVING RISE TO THE CLAIM OR CAUSE OF ACTION. BUYER AGREES
THAT IN NO EVENT SHALL SELLER'S LIABILITY TO BUYER AND/OR ITS CUSTOMERS EXTEND
TO INCLUDE INCIDENTAL, CONSEQUENTIAL OR PUNITIVE DAMAGES. THE TERM
"CONSEQUENTIAL DAMAGES" SHALL INCLUDE, BUT NOT BE LIMITED TO, LOSS OF
ANTICIPATED PROFITS, LOSS OF USE, LOSS OF REVENUE AND COST OF CAPITAL.
IMPORTANT INSTRUCTIONS
• Read all instructions prior to installing, operating, and servicing this product.
• Follow all warnings, cautions, and instructions marked on and supplied with this product.
• Inspect the equipment packing case and if damage exists, notify your local carrier for
liability.
• Open the packing list and carefully remove equipment and spare or replacement parts
from the case. Inspect all equipment for damage and missing parts.
• If items are damaged or missing, contact the manufacturer at 1 713 396 8880 for
instructions about receiving replacement parts.
• Install equipment as specified per the installation instructions and per applicable local and
national codes. All connections shall be made to proper electrical and pressure sources.
• Ensure that all equipment doors are closed and protective covers are in place, except
when maintenance is being performed by qualified persons, to prevent personal injury.
• Use of this product for any purpose other than its intended purpose may result in property
damage and/or serious injury or death.
• Before opening the flameproof enclosure in a flammable atmosphere, the electrical
circuits must be interrupted.
• Repairs must be performed using only authorized replacement parts as specified by the
manufacturer. Use of unauthorized parts can affect the product's performance and place
the safe operation of the product at risk.
• When installing or servicing ATEX-certified units, the ATEX approval applies only to
equipment without cable glands. When mounting the flameproof enclosures in a
hazardous area, only flameproof cable glands certified to IEC 60079-1 must be used.
• Technical assistance is available 24 hours a day, 7 days a week by calling 1 713 396 8880.
This page is intentionally left blank.
TABLE OF CONTENTS
DESCRIPTION 1.1 PURPOSE OF THIS MANUAL ..........................1-1
1.1.1 Section 1 Description ...................................1-1
1.1.2 Section 2 Equipment Description....................1-1
1.1.3 Section 3 Installation and Startup...................1-1
1.1.4 Section 4 Operation......................................1-1
1.1.5 Section 5 Maintenance .................................1-2
1.1.6 Section 6 Recommended Spare Parts..............1-2
1.1.7 Appendices ..................................................1-2
1.2 INTRODUCTION............................................1-2
1.3 FUNCTIONAL DESCRIPTION...........................1-4
1.4 MODES OF OPERATION.................................1-6
1.4.1 User Interfaces .............................................1-6
EQUIPMENT
DESCRIPTION
1.4.2 Capabilities...................................................1-6
1.5 THEORY OF OPERATION ...............................1-7
1.5.1 The Analyzer Detector ...................................1-7
1.5.2 Data Acquisition .........................................1-10
1.5.3 Peak Detection ...........................................1-11
1.5.4 Basic Analysis Computations ........................ 1-12
1.6 GLOSSARY ................................................1-16
2.1 SAMPLING SYSTEM......................................2-1
2.1.1 Sampling Point Location.................................2-2
2.1.2 Sample Volume and Flow Rate........................2-2
2.1.3 Sample Conditioning......................................2-3
2.1.4 Contamination Precautions .............................2-3
2.1.5 Valving ........................................................2-3
2 TABLE OF CONTENTS
Model 500
2.1.6 Calibration Gas .............................................2-4
2.2 ANALYZER...................................................2-5
2.2.1 Physical Description ......................................2-5
2.2.2 Chromatograph Valves................................... 2-7
2.2.3 Detector Subsystem ...................................... 2-8
2.2.4 Analyzer Preamplifier Unit ..............................2-9
2.2.5 Analyzer Specifications ..................................2-9
2.2.6 Utility Gas Requirements .............................. 2-10
2.3 CONTROLLER ............................................. 2-10
2.3.1 Controller Hardware Configurations ...............2-12
2.3.2 Optional Keypad and Display ........................ 2-25
2.3.3 Alarm Specifications.................................... 2-26
INSTALLATION AND
SETUP
3.1 PRECAUTIONS AND WARNINGS .................... 3-3
3.1.1 Hazardous Environments ................................3-4
3.1.2 Power Source Wiring .....................................3-5
3.1.3 Signal Wiring ................................................3-6
3.1.4 Electrical and Signal Ground ...........................3-8
3.1.5 Electrical Conduit ........................................ 3-10
3.1.6 Sample Systems Requirements ..................... 3-11
3.2 PREPARATION............................................ 3-12
3.2.1 Introduction................................................ 3-12
3.2.2 Site Selection .............................................3-13
3.2.3 Unpacking the Unit...................................... 3-14
3.2.4 Necessary Tools and Components................. 3-15
3.2.5 Optional Tools and Components.................... 3-16
3.3 INSTALLING THE ANALYZER .......................3-18
3.3.1 Point-to-point Wiring Guide,
Analyzer-Controller...................................... 3-18
Installation and Setup JULY 2010
Model 500
TABLE OF CONTENTS 3
3.3.2 Analyzer AC Power Wiring ........................... 3-26
3.3.3 Sample and Gas Lines..................................3-27
3.4 INSTALLING THE GC CONTROLLER ..............3-30
3.4.1 Modbus Slave Address (COM ID) Setup .........3-30
3.4.2 Controller-Analyzer Wiring ............................3-35
3.4.3 Controller PC Wiring (Serial Connections) .......3-37
3.4.4 CPU and COM4A Serial Communications
Setups .......................................................3-45
3.4.5 Controller Printer Wiring ...............................3-69
3.4.6 Discrete (Digital) I/O Wiring ..........................3-71
3.4.7 Analog I/O Wiring........................................3-74
3.4.8 Controller AC Power Wiring.......................... 3-77
OPERATION FROM
LOCAL KEYPAD AND
DISPLAY
3.5 ANALYZER LEAK CHECKS AND PURGING FOR
FIRST CALIBRATION ...................................3-78
3.5.1 Analyzer Leak Checks.................................. 3-78
3.5.2 Purging Carrier Gas Lines ............................. 3-80
3.5.3 Purging Calibration Gas Lines........................3-83
3.6 SYSTEM START-UP ....................................3-85
4.1 INTERFACE COMPONENTS FOR LOCAL DATA
DISPLAY AND ENTRY....................................4-3
4.1.1 Light Emitting Diode (Led) Indicators................ 4-3
4.1.2 Liquid Crystal Display (LCD) ...........................4-4
4.1.3 Keypad ........................................................4-4
4.2 LOGGING ON TO VIEW OR EDIT DATA ...........4-6
4.2.1 First Time Log-On..........................................4-6
4.2.2 Subsequent Log-On .......................................4-7
4.2.3 Start / Halt an Auto Sequence Analysis............4-8
4.2.4 Editing Procedures....................................... 4-10
4.2.5 Validity Checks of Data Entries .....................4-11
JULY 2010 Operation from Local Keypad and Display
4 TABLE OF CONTENTS
MAINTENANCE 5.1 TROUBLESHOOTING AND REPAIR CONCEPT ...5-2
Model 500
4.3 LOCAL DISPLAY MENUS ............................. 4-12
4.3.1 Main Menu .................................................4-14
4.3.2 Hardware Menu ..........................................4-14
4.3.3 Operator Entries Menu ................................. 4-15
4.3.4 Alarms Menu ..............................................4-16
4.3.5 Chromatogram Menu ................................... 4-16
4.3.6 GC Control Menu ........................................ 4-16
4.3.7 Data Records Menu ..................................... 4-17
4.3.8 Config Rpt - Maint. Log Menu....................... 4-17
5.2 ROUTINE MAINTENANCE...............................5-3
5.2.1 Model 500 Maintenance Checklist...................5-4
5.2.2 Routine Maintenance Procedures.....................5-5
5.2.3 Contract Service ...........................................5-5
5.3 LOCATING AND GAINING ACCESS TO EQUIPMENT
ELEMENTS ...................................................5-5
5.3.1 Analyzer Electrical/Electronic Units .................. 5-5
5.3.2 Detector Elements, Heater Elements, Valves and
Columns ......................................................5-7
5.4 PRECAUTIONS FOR HANDLING PRINTED CIRCUIT
ASSEMBLIES ................................................ 5-7
5.5 SERVICE, TROUBLESHOOTING, AND REPAIR
INSTRUCTIONS ............................................5-8
5.5.1 Preamplifier ................................................5-10
5.5.2 Temperature Control.................................... 5-10
5.5.3 Decoder .....................................................5-10
5.5.4 Analyzer Troubleshooting Guide .................... 5-13
5.5.5 Chromatograph Valves................................. 5-22
5.5.6 Detector Bridge Balance ...............................5-23
Maintenance JULY 2010
Model 500
TABLE OF CONTENTS 5
5.5.7 Temperature Measurements .........................5-25
5.5.8 Measure Vent Flow (MV) .............................5-27
5.5.9 Analog Inputs ............................................. 5-27
5.6 GC CONTROLLER MAINTENANCE................. 5-28
5.6.1 GC Controller Access...................................5-29
5.7 COMMUNICATIONS ....................................5-30
5.7.1 GC Controller Address Change...................... 5-31
5.8 ANALOG INPUTS AND OUTPUTS ................. 5-31
5.8.1 Analog Output Dialog Description.................. 5-32
5.8.2 Changing a Variable.....................................5-34
5.8.3 Changing the Bargraph.................................5-35
5.8.4 Performing a Manual Calibration.................... 5-37
RECOMMENDED SPARE
PARTS
5.8.5 Performing an Automated Calibration............. 5-39
5.8.6 Analog Loopback Test Circuits......................5-41
5.8.7 Upgrading Analog Outputs ...........................5-43
5.9 DISCRETE (DIGITAL) INPUTS AND OUTPUTS . 5-44
5.9.1 Digital Loopback Test Circuit ........................5-44
5.10 FUSE PROTECTION ..................................... 5-45
5.11 ANALYZER-CONTROLLER INTERCONNECT ....5-46
5.11.1 Function Codes........................................... 5-48
6.1 ANALYZER SPARES ......................................6-1
6.1.1 Printed Circuit Card Assemblies (Analyzer) .......6-1
6.1.2 Electrical and Mechanical Assemblies (Analyzer)6-1
6.2 GC CONTROLLER SPARES .............................6-3
6.2.1 Printed Circuit Card Assemblies
(GC Controller)..............................................6-3
6.2.2 Electrical and Mechanical Components (GC
Controller) ....................................................6-3
JULY 2010 Recommended Spare Parts
6 TABLE OF CONTENTS
Model 500
APPENDIX A,
SUPPLEMENTAL
WIRING GUIDE - SERIAL
COMMUNICATIONS
A.1 GC SERIAL PORT AND CABLE CONFIGURATIONS
FOR RS-232 .................................................A-1
A.2 RS-232 CONNECTION FROM GC CONTROLLER TO
PC...............................................................A-4
A.2.1 DB-9 Serial Port of GC to DB-9 Port of PC........A-4
A.2.2 DB-9 Serial Port of GC to DB-25 Port of PC ......A-5
A.2.3 Phoenix Plug Port of GC to DB-9 Port of PC......A-6
A.2.4 Phoenix Plug Port of GC to DB-25 Port of PC....A-7
A.3 RS-232 CONNECTION FROM GC CONTROLLER TO
EXTERNAL MODEM ......................................A-8
A.3.1 DB-9 Serial Port of GC to DB
Modem
........................................................A-8
A.3.2 Phoenix Plug Port of GC to DB-25 Port
Modem
........................................................A-9
-25 Port of
of
A.4 EXAMPLE RS-422 CONNECTION FROM PC TO
GC ............................................................A-10
APPENDIX B,
MANIFOLD FOR TWO
CARRIER GAS BOTTLES
TO GC SYSTEM
APPENDIX C, GUIDE TO
TRANSIENT
PROTECTION MODULES
A.5 EXAMPLE RS-485 CONNECTION FROM PC TO
GC ............................................................A-12
A.6 JUMPER-BASED SERIAL CHANNEL
CONFIGURATIONS......................................A-15
B.1 ILLUSTRATION ............................................. B-2
B.2 INSTALLATION AND LINE PURGING................ B-3
B.3 REPLACING CARRIER CYLINDER ....................B-4
C.1 PURPOSE OF THE TRANSIENT PROTECTION
MODULES....................................................C-1
C.2 PART APPLICATIONS, NUMBERS, AND
DESCRIPTIONS.............................................C-2
Appendix A, Supplemental Wiring Guide - Serial Communications JULY 2010
Model 500
APPENDIX D, INTERNAL
MODEM FOR GC
CONTROLLER
APPENDIX E, SETTING
SOLENOID PURGE
FLOWS
TABLE OF CONTENTS 7
C.3 TROUBLESHOOTING TRANSIENT PROTECTION
MODULES ....................................................C-4
APPENDIX F,
UPGRADING FROM
2251 TO 2350A GC
CONTROLLER
APPENDIX G, 2350 TO
2350A CPU RETROFIT
INSTRUCTIONS
F.1 HALT CURRENT ANALYSIS AND POWER
DOWN .........................................................F-1
F.2 NOTE EXISTING WIRING CONNECTIONS TO
2251 ...........................................................F-2
F.3 REMOVE CABLES, REPLACE CONTROLLER, AND
RECONNECT ................................................ F-5
G.1 2350A CPU ASSEMBLY INTRODUCTION........ G-1
G.2 CONVERSION PROCESS ............................... G-2
G.3 BASIC 2350A CONFIGURATION .................... G-7
G.4 2350A OPTIONS.......................................... G-9
G.4.1 The COM4A Board ....................................... G-9
G.5 TO ADD A MODEM .....................................G-12
G.6 TO ADD AN ETHERNET CARD......................G-15
APPENDIX H, 2350A
H.1 INTRODUCTION........................................... H-2
(LX-800) CPU RETROFIT
INSTRUCTIONS
H.2 REMOVING THE OLD CPU CARD ................... H-4
H.3 INSTALLING THE NEW CPU BOARD ............... H-6
H.4 INSTALLING A KEYBOARD AND DISPLAY WITH
COM4A BOARD........................................... H-7
JULY 2010 Appendix D, Internal Modem for GC Controller
8 TABLE OF CONTENTS
APPENDIX F, SHIPPING
AND LONG-TERM
STORAGE
RECOMMENDATIONS
ADDENDUM 1
ADDENDUM 2
Model 500
H.5 INSTALLING A KEYBOARD AND DISPLAY
WITHOUT COM4A BOARD.............................H-9
H.6 RETROFITTING THE ANALOG BOARD ...........H-11
H.6.1 Identifying your Analog Board .......................H-11
H.6.2 Installing a New Analog Board ......................H-13
H.7 REASSEMBLING THE 2350A ........................H-13
Appendix F, Shipping and long-term storage recommendations JULY 2010
DESCRIPTION
1.1 PURPOSE OF THIS MANUAL
This manual (P/N 3-9000-537) is intended as a user's guide to accompany
the Model 500 gas chromatograph.
For software operation instructions, see the MON2000 Software for
Gas Chromatographs User Manual (P/N 3-9000-522)
This manual provides the following information:
1.1.1 Section 1 Description
• A general description of the Model 500 gas chromatograph (GC) and
its components, their configurations and functions.
• A brief description of the GC's software, user interface, and
capabilities.
• Introduction to GC theory of operation and terminology.
1.1.2 Section 2 Equipment Description
• Guidelines for sampling system and gas connections.
• Descriptions of Analyzer subsystems and components.
• Descriptions of GC Controller subsystems and components.
1.1.3 Section 3 Installation and Startup
Instructions for installing the GC hardware.
1.1.4 Section 4 Operation
Instructions for operating the GC by means of its built-in keypad and
liquid crystal display (LCD), if provided.
1-2 Description
1.1.5 Section 5 Maintenance
• Instructions for regular maintenance and care of the GC hardware.
• Instructions for troubleshooting, repair, and service of the GC
hardware.
1.1.6 Section 6 Recommended Spare Parts
List of boards, valves, and other components suggested as spare parts.
1.1.7 Appendices
Appendices with additional, helpful reference materials and drawings.
1.2 INTRODUCTION
The Model 500 GC is a high-speed gas chromatograph that is factory
engineered to meet specific field application requirements based on
typical stream composition and the anticipated concentration of the
components of interest. The Model 500 typically consists of three major
components, the Analyzer Assembly, the Controller, and the Sample
Conditioning System:
Model 500 Gas Chromatograph
Analyzer Assembly (Model 500 Series) - Located near the sample tap.
The Analyzer includes GC columns, detectors, preamplifier, stream
switching valves, and solenoids. The Model 500 Analyzer is housed in a
National Electrical Manufacturers Association (NEMA) 7, National
Electrical Code (NEC) Class I, Division 1, Groups B, C, and D approved
enclosure, for use in a hazardous environment.
GC Controller - Located no further than 2000 feet (610 meters) away
from the Analyzer. The GC Controller includes electronics and ports for
signal processing, instrument control, data storage, personal computer
(PC) interface, and telecommunications. The GC Controller is available
in various enclosures and configurations, as follows:
Explosion Proof - NEMA 4X (weatherproof and corrosion resistant) and
NEMA 7, NEC Class I, Division 1, Groups B, C, and D approved
enclosure, for use in a hazardous environment. Available with or without
a built-in keypad and liquid crystal display (LCD).
Section 5 Maintenance JULY 2010
Model 500 Gas Chromatograph
Rack Mount - Suitable for use in a nonhazardous environment. Made
for mounting on a standard 19 inch rack. Available with or without a
built-in keypad and LCD.
Retrofit - Suitable for use in a nonhazardous environment. Made for
mounting on a 12-inch rack previously sold for 2251 GC Controller. The
Retrofit enclosure is not available with a built-in keypad and LCD
(therefore, a PC is required for operating).
Sample Conditioning System (SCS) - Located between the process
stream and the Analyzer sample inlet, usually mounted on the lower
portion of the Analyzer stand. The standard configuration SCS includes
a mounting plate, block (or shutoff) valves, and filters. Optionally, the
SCS can be configured with Genie® bypass filters, liquid shut-off valves,
and optional solenoids for stream switching: all of which can be enclosed
in an electric (heat tape design) oven.
Description 1-3
In its standard configuration, the Model 500 Analyzer can handle up to
five streams: typically, four for sample and one for calibration. With an
optional stream switch assembly added, the Model 500 Analyzer can
switch up to twelve streams, maximum.
The GC Controller, is designed to be operated primarily from a personal
computer (PC) running the MON2000 Software package. This provides
the user with the greatest capability, ease-of-use, and flexibility. One PC
running MON2000 can connect with up to 32 gas chromatographs. The
PC is used to display chromatograms and reports, which can then be
stored as files on the PC, or printed from either the PC's or the GC's
printer.
Also, each individual GC can be operated from its built-in keypad and
LCD (if installed in that configuration); however, this method offers more
limited functions. Display of the chromatograms on the LCD is
accomplished in scrolling strip chart fashion.
Since neither the PC nor a normal printer can be placed in a hazardous
area, serial port and Modbus communications links are provided for
connecting the Model 500 Analyzer to the PC, other computers, printers,
chromatographs, and Controllers.
JULY 2010 INTRODUCTION
1-4 Description
1.3 FUNCTIONAL DESCRIPTION
A functional block diagram of a typical Model 500 Analyzer installation is
shown in Figure 1-1. A sample of the gas to be analyzed is taken from the
process stream by a sample probe installed in the process line. The
sample passes through a sample line to the sample conditioning system
where it is filtered or otherwise conditioned. After conditioning, the
sample flows to the Analyzer for separation and detection of the
components of the gas.
The chromatographic separation of the sample gas into its components is
accomplished in the Analyzer in the following manner. A precise volume
of sample gas is injected into one of the unit's analytical columns. The
column contains a stationary phase (packing) that is either an active solid
(adsorption partitioning) or an inert solid support that is coated with a
liquid phase (absorption partitioning). The gas sample is moved through
the column by means of a mobile phase (carrier gas). Selective
retardation of the components of the sample takes place in the column
that causes each component to move through the column at a different
rate. This action separates the sample into its constituent gases and
vapors.
Model 500 Gas Chromatograph
A detector located at the outlet of the analytical column senses the
elution of components from the column and produces electrical outputs
proportional to the concentration of each component. Outputs from the
Analyzer detectors are amplified in the Analyzer electronics, then
transmitted to the GC Controller for further processing. See also, Section
1.5, “Theory of operation” on page 7.
Output from the GC Controller is normally displayed on a remotely
located personal computer (PC) or a printer. Connection between the GC
Controller and the PC can be accomplished via a direct serial line, the
Modbus-compatible communication interface, modem or ethernet card.
Multiple chromatograms may be displayed on the PC monitor, and
compared or contrasted with separate color schemes. This allows a stored
chromatogram to be compared/contrasted with a current or another
stored chromatogram. This could be of great assistance when changing
parameters or isolating a problem.
FUNCTIONAL DESCRIPTION JULY 2010
Model 500 Gas Chromatograph
Use of a PC for configuration and troubleshooting procedures is essential
in most instances. Basic operations can also be performed from a keypad
and liquid crystal display that are built into certain versions of the GC
Controller. The PC may be remotely connected via telephone, radio,
ethernet or satellite communications. Once installed and configured, the
Model 500 Analyzer can operate independently for long periods of time.
Description 1-5
Figure 1-1 Model 500 Analyzer Functional Block Diagram
JULY 2010 FUNCTIONAL DESCRIPTION
1-6 Description
1.4 MODES OF OPERATION
1.4.1 User Interfaces
You have at least one, and optionally two, user interfaces from which to
operate the gas chromatograph (GC) system:
PC connected to the GC and running MON2000 - The PC
connected to the GC and running MON2000 offers the greatest
amount of capability and flexibility.
Find complete user instructions for MON2000 in the program's online
HELP screens and in the program user's manual, MON2000 Software
for Gas Chromatographs User Manual (P/N 3-9000-522).
or
The GC Controller's built-in keypad and LCD - The GC
Controller's built-in keypad and LCD offer essential startup and
operation functions. They are useful in a hazardous environment or if
no PC is available.
Model 500 Gas Chromatograph
This feature is optional on all standalone models of the GC, except the
portable Compact BTU GC.
1.4.2 Capabilities
Individual gas chromatograph Controller functions that can be initiated
or controlled by the GC and its software, MON2000, are listed in the
MON2000 Software for Gas Chromatographs User Manual (P/N 3-9000-
522).
Modes of operation JULY 2010
Model 500 Gas Chromatograph
1.5 THEORY OF OPERATION
See also Section 1.6, “GLOSSARY” on page 16, for definitions
of some of the terminology used in the following explanations.
1.5.1 The Analyzer Detector
The Analyzer detector subsystem is a thermal conductivity detector that
consists of a balanced bridge network with heat-sensitive thermistors in
each leg of the bridge. Each thermistor is enclosed in a separate chamber
of the detector block. One thermistor is designated the reference element
and the other the measurement element. A schematic diagram of the
thermal conductivity detector is shown in Figure 1-2.
Description 1-7
JULY 2010 Theory of operation
1-8 Description
Model 500 Gas Chromatograph
Figure 1-2 Schematic Diagram of Analyzer Detector Bridge
In the quiescent condition (prior to injecting a sample), both legs of the
bridge are exposed to pure carrier gas. In this condition, the bridge is
balanced and the bridge output is electrically nulled. (The bridge can be
balanced by the fine and coarse adjustment potentiometers located on the
preamplifier circuit board.)
The analysis begins when a fixed volume of sample is injected into the
column by operation of the sample valve. The sample is moved through
the column by the continuous flow of carrier gas. As successive
components elute from the column, the temperature of the measurement
element changes. The temperature change unbalances the bridge and
produces an electrical output proportional to the component
concentration. The differential signal developed between the two
thermistors is amplified by the preamplifier.
The Analyzer Detector JULY 2010
Model 500 Gas Chromatograph
Figure 1-3 illustrates the change in detector electrical output during
elution of a component.
Figure 1-3 Detector output during component elution
1. Detector bridge balanced.
Description 1-9
2. First component begins to elute from column and to be sensed by the
measurement thermistor.
3. Peak concentration of first component.
4. Second component begins to elute from column and to be sensed by the
measurement thermistor.
5. Peak concentration of second component.
In addition to amplifying the differential signal developed between the
detector's two thermistors, the preamplifier also supplies drive current to
the detector bridge. The preamplifier also supplies drive current to the
detector bridge. The voltage signal is converted to a 4 to 20-milliamp
(mA) current loop for transmission to the GC Controller. The signal is
proportional to the concentration of a component detected in the gas
sample. The preamplifier provides four different gain channels as well as
compensation for baseline drift. The signals from the preamplifier are
sent to the GC Controller for computation, recording on a printer, or
viewing on a PC monitor or LCD.
JULY 2010 The Analyzer Detector
1-10 Description
1.5.2 Data Acquisition
Every second, exactly 40 equi-spaced data samples are taken for analysis
by the GC Controller (i.e., once every 25 milliseconds). Each data sample,
after having been precision-amplified, is subjected to a sixteen bit analog
to digital (A/D) conversion. The sampling frequency of 40 Hertz (Hz) was
chosen to reduce 60 Hz normal mode noise.
After each point on the chromatograph signal is sampled, the resulting
number is stored in a buffer area in the GC Controller's memory for
processing. During the analysis, only the last 256 data points are
available for processing. Because the data analysis is done as the signal
is sampled (in real-time), only a limited number of past data samples is
required to analyze any signal.
As a part of the data acquisition process, groups of incoming data samples
are averaged together before the result is stored to the Controller's
memory for processing. Non-overlapping groups of N samples are
averaged and stored, and thus reduce the effective incoming data rate to
40/N samples/second. For example, if N = 5, then a total of 40/5 or 6
(averaged) data samples are stored every second. The value for the
variable N is determined by the selection of a Peak Width parameter
(PW). The relationship is:
Model 500 Gas Chromatograph
N PW ondssec=
where PW is given in seconds. All the various details in the analysis
process are independent of the value of N. Allowable values of N are 1 to
63, which corresponds to values of PW from 1 to 63 seconds.
The variable N is known as the integration factor. This term is used
because N determines how many points are averaged or integrated to
form a single value. The integration of data upon input, before storing,
serves two purposes. First, the statistical noise on the input signal is
reduced by the square root of N. In the case of N = 4, a noise reduction of
two would be realized. Secondly, the integration factor controls the
bandwidth of the chromatograph signal. It is necessary to match the
bandwidth of the input signal to that of the analysis algorithms in the GC
Data Acquisition JULY 2010
Model 500 Gas Chromatograph
Controller. This prevents small, short duration perturbations from being
recognized as true peaks by the program. It is therefore important to
choose a Peak Width corresponding to the narrowest peak in a group
under consideration.
1.5.3 Peak Detection
For normal area or peak height concentration evaluation, the
determination of a peak's start, peak point, and end is automatic. The
manual determination of start and end points is used only for area
calculations in the Forced Integration mode. Automatic determination of
peak onset or start is initiated whenever Integrate Inhibit is turned off.
Analysis is started in a region of signal quiescence and stability, such
that the signal level and activity can be considered as baseline values. It
is important that this be the case because this assumption is made by the
GC Controller.
Description 1-11
Having initiated a peak search by turning Inhibit off, the GC Controller
performs a point by point examination of the signal slope. This is
achieved by using a digital slope detection filter which is a combination
low pass filter and differentiator. The output of this detector is
constantly compared to a system constant entered by the operator called
Slope Sensitivity. A default value of 8 is assumed if no entry is made.
Lower values make peak onset detection more sensitive, and higher
values make detection less sensitive. Higher values (20 to 100) would be
appropriate for noisy signals, e.g. high amplifier gain.
Peak termination is determined by the same application of this detector
to the signal, but in the reverse sense. Onset is defined where the
detector output exceeds the baseline constant, but termination is defined
subsequently where the detector output is less than the same baseline
constant.
Sequences of fused peaks are also automatically handled. This is done by
testing each termination point to see if the region immediately following
it satisfies the criteria of a baseline. A baseline region must have a slope
detector value less than the magnitude of the baseline constant for a
number of sequential points. When a baseline region is found, this
terminates a sequence of peaks.
JULY 2010 Peak Detection
1-12 Description
Model 500 Gas Chromatograph
A zero reference line for peak height and area determination is
established by extending a line from the point of the onset of the peak
sequence to the point of the termination. The values of these two points
are found by averaging the four integrated points just prior to the onset
point and just after the termination points, respectively. The zero
reference line will, in general, be non-horizontal, and thus compensates
for any linear drift in the system from the time the peak sequence starts
until it ends.
In a single peak situation, peak area is the area of the component peak
between the curve and the zero reference line. The peak height is the
distance from the zero reference line to the maximum point on the
component curve. The value and location of the maximum point is
determined from quadratic interpolation through the three highest points
at the peak of the discrete valued curve stored in the GC Controller.
For fused peak sequences, this interpolation technique is used both for
peaks as well as valleys (minimum points). In the latter case, lines are
dropped from the interpolated valley points to the zero reference line to
partition the fused peak areas into individual peaks. The use of
quadratic interpolation improves both area and height calculation
accuracy and eliminates the effects of variations in the integration factor
on these calculations.
For calibration, the GC Controller may average several analyses of the
calibration stream.
1.5.4 Basic Analysis Computations
Two basic analysis algorithms are included in the GC Controller. These
are:
• Area Analysis - Calculates area under component peak
• Peak Height Analysis - Measures height of component peak
Concentration Analysis by Using Response Factor
Concentration calculations require a unique response factor foreach
component in an analysis. These response factors may be manually
entered by an operator or determined automatically by the system
Basic Analysis Computations JULY 2010
Model 500 Gas Chromatograph
through calibration procedures (with a calibration gas mixture that has
known concentrations).
Response factor calculation: (using the external standard)
or
where:
ARF
HRF
n
=
=
n
Area
-------------- -
Cal
Ht
-----------
Cal
Description 1-13
n
n
n
n
ARF
HRF
Area
Ht
Cal
Area response factor for component n in area per mole percent (%).
n
Height response factor for component n.
n
Area associated with component n in calibration gas.
n
Height associated with component n in mole percent in calibration gas.
n
Amount of component n in mole percent in calibration gas.
n
Calculated response factors are stored by the GC Controller for use in the
concentration calculations, and are printed out in the configuration and
calibration reports.
Average response factor is calculated as follows:
k
RF
i
∑
i 1=
------------------
RFAVG
=
n
k
JULY 2010 Basic Analysis Computations
1-14 Description
where:
RFAVGnArea or height average response factor for component n.
Model 500 Gas Chromatograph
Rf
i
Area or height response factor for component n from the calibration run.
k Number of calibration runs actually used to calculate the response
factors.
The percent deviation of new RF averages from old RF average is
calculated in the following manner:
% deviation
new
------------------------------------
RF
old
old
100×=
RF
–
RF
where the absolute value of % deviation for alarm has been previously
entered by the operator.
Concentration Calculations in Mole % without Normalization
Once response factors have been determined by the GC Controller or
entered by the operator, component concentrations are determined for
each analysis by using the following equations:
Area
n
-------------- -
CONC
=
n
ARF
n
or
Ht
n
CONC
--------------
=
n
HRF
n
where:
CONC
Area
Basic Analysis Computations JULY 2010
Concentration of component n in mole percent.
n
Area of component n in unknown sample
n
Model 500 Gas Chromatograph
Description 1-15
ARF
Response factor of component n calculated from area of calibration
n
sample. Units are area per mole percent.
Ht
n
HRF
Peak height of component n in unknown sample
Response factor of component n calculated from peak height of cal-
n
ibration sample. Units are height per mole percent.
Note that the average concentration of each component will also be
calculated when data averaging is requested.
Component concentrations may be input through analog inputs 1 - 4 or
may be fixed. If a fixed value is used, the calibration for that component
is the mole % that will be used for all analyses.
Concentration Calculations with Normalization
CONC
CONCN
n
----------------------------
∑
i 1=
k
CONC
n
100×=
i
where:
CONCN
CONC
CONC
k Number of components to be included in the normalization.
Normalized concentration of component n in percent of total gas
n
concentration.
Non-normalized concentration of component n in mole percent.
n
Non-normalized concentration (in mole percent) from each of the k
i
components to be grouped into this normalization.
JULY 2010 Basic Analysis Computations
1-16 Description
For additional information about other calculations that are
performed by the GC Controller and software, see the
MON2000 Software for Gas Chromatographs user manual (P/N
3-9000-522).
1.6 GLOSSARY
Auto Zero: Automatic zeroing of the preamplifier. May be entered into
the Controller to take place at any time during the analysis when either
the component is not eluting or the baseline is steady.
Chromatogram: A permanent record of the detector output. A
chromatograph is obtained from a PC interfaced with the detector output
through the GC Controller. A typical chromatogram displays all
component peaks, and gain changes. It may be viewed in color as it is
processed on a PC VGA display. Tick marks recorded on the
chromatogram by the GC Controller indicate where timed events take
place.
Model 500 Gas Chromatograph
Component: Any one of several different gases that may appear in a
sample mixture. For example, natural gas usually contains the following
components: nitrogen, carbon dioxide, methane, ethane, propane,
isobutane, normal butane, isopentane, normal pentane, and hexanes
plus.
Condulet: Fitting resembling a pipe or a box with a removable cover for
access to electric conduits.
CTS: Clear to send (a serial port pin assignment).
DCD: Data carrier detect; see also, RLSD (a serial port pin assignment).
DSR: Data set ready (a serial port pin assignment).
DTR: Data terminal ready (a serial port pin assignment).
GLOSSARY JULY 2010
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