Emerson Rosemount 700XA User manual

Reference Manual
2-3-9000-744, Rev H
July 2020
Rosemount™ 700XA
Gas Chromatograph

Overview
This section provides a description of the Rosemount 700XA system, an explanation of the theory of operation, and a glossary of
chromatograph terminology.
Contents
Overview........................................................................................................................................................................................... 2
Equipment description and specifications....................................................................................................................................... 21
Getting started................................................................................................................................................................................32
Installation and start-up ..................................................................................................................................................................35
Operation and maintenance............................................................................................................................................................72
Troubleshooting............................................................................................................................................................................137
Local operator interface (LOI)........................................................................................................................................................ 0
Carrier gas installation and maintenance....................................................................................................................................... 0
Micro flame photometric detector (µFPD)..................................................................................................................................... 0
Recommended spare parts............................................................................................................................................................0
Shipping and long-term storage recommendations...................................................................................................................... 0
Pre-defined Modbus® Map Files..................................................................................................................................................... 0
Engineering drawings....................................................................................................................................................................0
July 2020
2 Emerson.com/Rosemount

Glossary
Auto zero The thermal conductivity detector (TCD) is auto zeroed at the start of a new analysis. The operator can also
configure automatic zeroing of the TCD amplifier to take place at any time during the analysis if the
component is not eluting or the baseline is steady. The flame ionization detector (FID) will auto zero at each
new analysis run and can be configured to auto zero anytime during the analysis if the component is not eluting
or the baseline is steady.
Baseline Signal output when there is only carrier gas going across the detectors. In a chromatogram you should only see
Baseline when running an analysis without injecting a sample.
Carrier gas The gas used to push the sample through the system during an analysis.
Chromatogram A permanent record of the detector output. A chromatogram is obtained from a personal computer (PC)
interfaced with the detector output through the controller assembly. A typical chromatogram displays all
component peaks, and gain changes. It may be viewed in color as it is processed on a PC display. Tick marks
recorded on the chromatogram by the controller assembly indicate where timed events take place.
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.
CDT Component data table
CTS Clear to send.
DCD Data carrier detect.
DSR Data set ready.
DTR Data terminal ready.
FID Flame ionization detector. The optional FID may be used in place of a TCD for the detection of trace
compounds. The FID requires a polarization voltage and its output is connected to the input to a high
impedance amplifier, an electrometer. The sample of gas to be measured is injected into the burner with a
mixture of hydrogen and air to maintain the flame.
FPD Flame photometric detector. The FPD is used to analyze gas compound impurities, such as sulfur,
phosphorous, and metals. When sample gas passes through the hydrogen/air flame the component's
wavelengths emitted are electrically measured. The micro FPD (µFPD) is located in the analyzer's upper
enclosure.
GC Gas ghromatograph. The GC is a user-configurable analyzer for various process gas applications.
LSIV Liquid sample injection valve. The optional LSIV is used to convert a liquid sample to a gas sample by vaporizing
the liquid in a heated chamber, so the resulting gas sample can be analyzed.
Methanator The optional methanator, also known as a catalytic converter, transforms the components that are
undetectable by the FID, carbon dioxide and/or carbon monoxide, into methane by adding hydrogen and heat
to the sample.
Note
Carbon dioxide and/or carbon monoxide components are detectable by the TCD.
Response factor Correction factor for each component as determined by the following calibration:
Retention time Time, in seconds, that elapses between the start of analysis and the sensing of the maximum concentration of
each component by the detector.
RI Ring indicator.
RLSD Received line signal detect. A digital simulation of a carrier detect.
RTS Request to send.
July 2020
Rosemount 700XA 3

RxD, RD, or Sin Receive data, or signal in.
TCD Thermal conductivity detector. A detector that uses the thermal conductivity of the different gas components
to produce an unbalanced signal across the bridge of the preamplifier. The higher the temperature, the lower
the resistance on the detectors.
TxD, TD, or Sout Transmit data, or signal out.
System description
The Rosemount 700XA is a high-speed gas chromatograph (GC) system that is engineered to meet specific field application
requirements based on typical hydrocarbon stream composition and anticipated concentration of selected components. In its
standard configuration, the analyzer can handle up to eight streams: seven sample streams and one calibration stream.
The Rosemount 700XA system consists of two major parts: the analyzer assembly and the electronics assembly. Depending upon
the particular GC, there may also be a third, optional, assembly called the sample conditioning system (SCS).
The electronics and hardware are housed in an explosion-proof enclosure that meets the approval guidelines of various certification
agencies for use in hazardous environments. See the certification tag on the GC for specific details about agency approvals.
Analyzer assembly
The analyzer assembly includes:
■Columns
■Thermal conductivity detectors (TCDs)
■Flame ionization detectors (FIDs)
■Flame photometric detector (FPD)
■Preamplifer
■Preamplifier power supply
■Stream switching valves
■Analytical valves
■Solenoids
Additionally, the Rosemount 700XA can be equipped with a liquid sample injection valve (LSIV) or methanator.
For more information, see Upper compartment.
Electronics assembly
The electronics assembly includes the electronics and ports necessary for signal processing, instrument control, data storage,
personal computer (PC) interface, and telecommunications.
The operator uses the electronics assembly and MON2020 to control the gas chromatograph (GC). Refer to Electronics hardware
for more details.
The GC-to-PC interface provides you with the greatest capability, ease-of-use, and flexibility. You can use MON2020 to edit
applications, monitor operations, calibrate streams, and display analysis chromatograms and reports, which can then be stored as
files on the PC’s hard drive or printed from a printer connected to the PC.
July 2020
4 Emerson.com/Rosemount

WARNING
HAZARDOUS AREA EXPLOSION HAZARD
Failure to follow this warning may result in injury or death to personnel.
Do not use a personal computer (PC) or printer in a hazardous area.
Emerson provides serial and Ethernet communication links to connect the analyzer to the PC and to connect to other
computers and printers in a safe area.
Sample conditioning system (SCS)
The optional sample conditioning system is located between the process stream and the sample inlet, which is often mounted
below the gas chromatograph (GC).
The standard SCS configuration includes a stream switching system and filters.
Functional description
A sample probe installed in the process line takes a sample of the gas to be analyzed from the process stream. The sample passes
through a sample line to the sample conditioning system (SCS) where it is filtered or otherwise conditioned. After conditioning, the
sample flows to the analyzer assembly for separation and detection of the gas components.
Figure 1: Gas Chromatography Process Model
A. Process line
B. Probe
C. Sample system
D. Chromatograph oven
E. Gas chromatograph (GC) controller
F. Sample return
G. Slip stream
H. Carrier gas
I. Reference vent
J. Detector vent
K. Analysis results
Separation and analysis
The GC separtes the sample gas into its components as follows:
July 2020
Rosemount 700XA 5

1. A precise volume of sample gas is injected into one of the analytical columns. The column contains a stationary phase
(packing) that is either an active solid or an inert solid support that is coated with a liquid phase (absorption partitioning).
2. A mobile phase (carrier gas) moves the sample gas through the column.
3. The selective retardation of the components takes place in the column, causing each component to move through the
column at a different rate. This separates the sample into its constituent gases and vapors.
4. 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.
Output from the electronic assembly is normally displayed on a remotely located personal computer (PC) or in a distributed control
system (flow computer).
To connect the GC to a PC, use a direct serial line, an optional Ethernet cable, or a Modbus®-compatible communication interface.
Several chromatograms may be displayed via MON2020 with separate color schemes, allowing you to compare present and past
data.
In most cases, it is essential to use MON2020 to configure and troubleshoot the GC. The PC may be remotely connected via
Ethernet, telephone, radio or satellite communications. Once installed and configured, the GC can operate independently for long
periods of time.
Software description
The GC uses two distinct types of software. This enables total flexibility in defining the calculation sequence, report content,
format, type and amount of data for viewing, control, and/or transmission to another computer or controller assembly. The two
types are:
■Embedded GC firmware
■MON2020 software
The application configuration is tailored to the customer’s process and shipped on a USB stick. The hardware and software are
tested together as a unit before the equipment leaves the factory.
MON2020 communicates with the GC and can be used to initiate site system setup, i.e., operational parameters, application
modifications, and maintenance.
Embedded GC firmware
The GC’s embedded firmware supervises operation of the Rosemount 700XA through its internal microprocessor-based controller.
All direct hardware interface is via this control software. It consists of a multi-tasking program that controls separate tasks in system
operation, as well as hardware self-testing, user application downloading, startup, and communications. Once configured, the
Rosemount 700XA can operate as a stand alone unit.
July 2020
6 Emerson.com/Rosemount

MON2020
MON2020 provides operator control of the Rosemount 700XA, monitors analysis results, and inspects and edits various parameters
that affect the analyzer operation. It also controls display and printout of the chromatograms and reports, and it stops and starts
automatic analysis cycling or calibration runs.
After the equipment/software has been installed and the operation stabilized, automatic operation takes place over an Ethernet
network.
MON2020 is a Windows™-based program that allows you to maintain, operate, and troubleshoot a gas chromatograph (GC).
Individual GC functions that can be initiated or controlled by MON2020 include, but are not limited to, the following:
■Valve activations
■Timing adjustments
■Stream sequences
■Calibrations
■Baseline runs
■Analyses
■Halt operation
■Stream/detector/heater assignments
■Stream/component table assignments
■Stream/calculation assignments
■Diagnostics
■Alarm and event processing
■Event sequence changes
■Component table adjustments
■Calculation adjustments
■Alarm parameters adjustments
■Analog scale adjustments
■Local operator interface (LOI) variable assignments (optional)
Reports and logs that can be produced, depending upon the GC application in use, include, but are not limited to, the following:
■Configuration report
■Parameter list
■Analysis chromatogram
■Chromatogram comparison
■Alarm log (unacknowledged and active alarms)
■Event log
■Various analysis reports
For a complete list of the GC functions, reports, and logs available through MON2020, consult the MON2020 for Gas
Chromatographs Reference Manual (P/N 2-3-9000-745).
Theory of operation
The following sections discuss the theory of operation for the gas chromatograph, including the engineering principles and
concepts used.
July 2020
Rosemount 700XA 7

Note
See Glossary for definitions of the terminology used in this document.
Thermal conductivity detector (TCD)
One of the detectors available on the gas chromatograph (GC) is a TCD, which 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 thermistor is designated the measurement element. See Figure
2 for a schematic diagram of the TCD.
Figure 2: Analyzer Assembly with TCD Bridge
A. Detector block (in heated upper section of analyzer)
B. Reference flow (carrier gas)
C. Measurement flow ("MV")
D. Signal out
E. Preamplifier (in analyzer electronics housing)
F. Detector bridge
G. DC power
H. Valves, columns, etc.
July 2020
8 Emerson.com/Rosemount

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 analysis begins when the sample valve injects a fixed volume of sample into the column. The continuous flow of carrier gas
moves the sample through the column. 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. Figure 3 illustrates the change in
detector electrical output during elution of a component.
Figure 3: Detector Output during Component Elution
A. Detector bridge balanced
B. Component begins to elute from column and is measured by thermistor.
C. Peak concentration of component
In addition to amplifying the differential signal developed between the two thermistors, the preamplifier supplies drive current to
the detector bridge.
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 electronic assembly for component concentration computation, recording, or
viewing on a PC monitor with MON2020.
Flame ionization detector (FID)
Another detector available for the Rosemount 700XA is the flame ionization detector (FID).
The FID requires a polarization voltage, and its output is connected to the input to a high impedance amplifier that is called an
electrometer. The burner uses a mixture of hydrogen and air to maintain the flame. The sample of gas to be measured is also
injected into the burner. See Figure 4 for a schematic diagram of the FID.
July 2020
Rosemount 700XA 9

Figure 4: Analyzer Assembly with FID Detector Bridge
A. Polarizing voltage
B. Electrometer
C. Signal out
D. Sample/hydrogen (H2)
E. Air
Micro flame photometric detector (µFPD) burner
The flame photometric detector (FPD) is a very sensitive and selective detector for the analysis of sulfur or organophosphorus
containing compounds. The detector is very stable and easy to use.
As the analyte is burned in a hydrogen and air flame, a characteristic wavelength of light is emitted at 394 nm for sulfur. The
emitted light is amplified by the photomultiplier tube (PMT) and processed by the signal processor. The response to phosphorus is
linear and quadratic to sulfur.
The Emerson µFPD solution consists of three key parts: burner, fiber cable, and PMT electronics. The hydrogen and air in the burner
help to burn the sample containing sulfur components. The light emitted from the chemical reaction is then transmitted using the
fiber cable from the oven assembly to the electronics module. The PMT electronics module consists of a 394 nm filter, a
photomultiplier tube (PMT), and all the necessary electronics to digitize the signal. The digtial signal is then transmitted to the main
central processing unit (CPU) using CAN bus.
July 2020
10 Emerson.com/Rosemount