Teledyne 7120 User Manual

Table of Contents

OPERATING INSTRUCTIONS

Model 7120

Photometric IR Analyzer

Table of Contents

Explosion Proof for

Class I, Division I, Groups B, C, D

Teledyne Analytical Instruments

Model 7120 Photometric Analyzer

Table of Contents

1 Introduction

1.1 Overview........................................................................ 1-1

1.2 Typical Gas Applications................................................ 1-1

1.3 Main Features of the Analyzer ....................................... 1-2

1.4 General .......................................................................... 1-3

1.5 NDIR Analyzer............................................................... 1-3

2 Installation

2.1 Unpacking the Analyzer................................................. 2-1

2.2 Installing & Connecting the Analyzer ............................. 2-1

2.2.1 IUser Connections ................................................ 2-2

2.2.2 Electrical Power Connections ............................... 2-2

2.2.3 Calibration Gases ................................................. 2-2

2.2.4 Pipe Connection ................................................... 2-3

2.2.5 Sample Delivery System....................................... 2-3

2.2.6 Venting the System ............................................... 2-3

2.3 Electrical Connections (rear Panel) ............................... 2-3

2.3.1 Primary Input Power .............................................. 2-4

2.3.2 Fuse Installation .................................................... 2-4

2.3.3 50-Pin Equipment Interface Connector ................. 2-4

2.3.3.1 Analog Outputs .............................................. 2-4

2.3.3.2 Alarm Relays ................................................. 2-6

2.3.3.3 Digital Remote Cal Input................................ 2-7

2.3.3.4 Range ID Relays ........................................... 2-9

2.3.3.5 Network I / O .................................................. 2-9

2.3.3.6 Remote Valve Connector ............................... 2-9

2.3.4 RS-232 Port .......................................................... 2-10

2.4 Gas Requirements ......................................................... 2-12

2.5 Testing the System......................................................... 2-12

2.6 Calibration ..................................................................... 2-12

2.6.1 Calibration Fluids .................................................. 2-12

2.6.2 Calibration............................................................. 2-13

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Table of Contents

3 Start-up and Theory of Operation .........................................3-1

3.1 Preliminary..................................................................... 3-1

3.2 NDIR Analyzer set-up .................................................... 3-1

3.2.1 Initial Set-up and Zeroing ...................................... 3-1

3.2.2 Operational Calibration ......................................... 3.2

3.3 Theory of Operation ....................................................... 3-2

3.3.1 General................................................................. 3-2

3.4.2 Analyzer ................................................................ 3-3

3.4 Circuit Description ......................................................... 3-5

3.5 Digital Signal Processing & Electronics ......................... 3-6

3.6 Linearizer....................................................................... 3-7

3.7 Control Unit.................................................................... 3-8

3.8 Automatic Function ........................................................ 3-9

4 Operation: Electrical/Control Unit Modes/Functioning

4.1 Introduction .................................................................... 4-1

4.2 Using the Controls ......................................................... 4-2

4.2.1 Mode/Function Selection ...................................... 4-2

4.2.1.1 Analysis Mode............................................ 4-2

4.2.1.2 Setup Mode ................................................ 4-4

4.2.2 Data Entry ............................................................. 4-5

4.2.2.1 Enter........................................................... 3-5

4.2.2.2 Escape ....................................................... 3-5

4.3.2 Setting up Auto-Cal................................................ 4-6

4.3.3 Password Protection .............................................. 4-7

4.3.3.1 Entering the Password................................... 4-7

4.3.3.2 Installing or Changing the Password ............. 4-8

4.3.4 Logging Out ........................................................... 4-9

4.3.5 System Self-Diagnostic Test .................................. 4-9

4.3.6 The Model Screen ................................................. 4-10

4.3.7 Checking Linearity with Algorithm ......................... 4-10

4.3.8 Trouble Shooting Information ................................. 4-11

4.3.9 Digital Flter Setup .................................................. 4-12

4.3.10 Zero Offset Adjustment .......................................... 4-13

4.3.11 CAL-OUT Funtion.................................................. 4-14

4.4 The Zero and Span Functions ....................................... 4-16

4.4.1 Zero Cal ................................................................. 4-16

4.4.1.1 Auto Mode Zeroing ........................................ 4-17

3.4.1.2 Manual Mode Zeroing.................................... 4-18

3.4.1.3 Cell Failure .................................................... 4-18

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Model 7120 Photometric Analyzer

4.4.2 Span Cal................................................................ 4-19

4.4.2.1 Auto Mode Spanning ..................................... 4-19

4.4.2.2 Manual Mode Spanning................................. 4-20

4.5 The Alarms Function...................................................... 4-21

4.6 The Range Select Function ........................................... 4-23

4.6.1 Manual (Select/Define Range) Screen .................. 4-23

4.6.2 Auto Screen ........................................................... 4-24

4.6.3 Precautions............................................................ 4-25

4.7 The Analyze Function .................................................... 4-26

4.8 Programming ................................................................. 4-27

4.8.1 The Set Range Screen .......................................... 4-27

4.8.2 The Curve Algorithm Screen ................................. 4-29

4.8.2.1 Checking the Linearization ............................ 4-29

4.8.2.2 Manual Mode Linearization ........................... 4-30

4.8.2.3 Auto Mode Linearization................................ 4-31

4.9 Special Function Setup.................................................. 4-32

4.9.1 Offset Output / Reverse Output............................... 4-32

4.9.1.1 Output Signal Reversal.................................. 4-32

4.9.1.2 Output Signal Offset....................................... 4-33

4.9.2 Polarity Reversal.................................................... 4-33

4.9.3 Gain Preset............................................................ 4-34

5 Maintenance

5.0 Fuse Replacement ......................................................... 5-1

5.1 Routine Maintenance..................................................... 5-2

5.2 Filter............................................................................... 5-2

5.3 NDIR Analyzer Measurement Cell................................. 5-3

5.4 System Self Diagnostic Test........................................... 5-3

5.5 Major Internal Components............................................ 5-4

5.6 Troubleshooting ............................................................. 5-7

6.7 General .......................................................................... 5-7

5.8 Troubleshooting Chart ................................................... 5-8

A Appendix

Model 7120 Specifications..................................................... A-1

Recommended 2-Year Spare Parts List ................................. A-4

Drawing List........................................................................... A-4

Exceptions, Gas Cnditions..................................................... A-6

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Photometric Analyzer Introduction 1

1.0 Introduction

1.1 Overview

The Teledyne Analytical Instruments Model 7120 Analyzer, is versatile

microprocessor-based instrument.

The manual covers the Model 7120 Explosion Proof Bulk mounted analyzer. Consisting of an Analysis section and Control Unit section. The 7120 Analyzer is for indoor or protected use in Explosion Proof environments only.

1.2 Typical Gas Applications

Typical applications of the Model 7120 are for ppm’s to % ranges:

• 95 to 100%CO2 purity for the Beverage Industry

Other gas purity applications are: 90 or 95-100% CO, 98-100%

C2H4 (ethylene), 90-100% CH4 (methane). Others possible, consult factory.

• 500 to 2000ppm ranges of H2Ov in INERT GASES, CL2, COCL2, CO,

CO2, etc. % levels also possible.

• Chemical/Petrochemical: FCC gases, off gases, reforming/process gases:

CO, CH4, C2...C6, C2H4, etc.

• Ammonia Plants: Catalyst protection, process

control: CO, CO2, NH3

• Ethylene Plants C2H4 purity, CO, CO2, CH4

• H2, Syn/Natural Gas, Fuel cell plants 90 or 95%-100% CO purity, CO2,

CH4

• Iron plants or Metal Processing Coke, Blast, Electric furnaces:

CO, CO2, CH4

• All Industries Drying ovens, moisture control

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1 Introduction Model 7100

• Sulfuric acid plants 0-15% SO2, 1000ppm CO, 20%CO2

• Blanketing of perishables Leak detection, fermentators, controlled atmospheres

• Carbon bed breakthrough detection ppm’s to % levels, CO, CO2, HC’s

• Mining/Landfill/Sewerage CO, CO2, CH4, C2-C6 HC’s, H2Ov (500ppm to 8% possible

1.3 Main Features of the Analyzer

The Model 7120 Photometric Analyzer is sophisticated yet simple to

use. The main features of the analyzer include:

• A easy-to-use front panel interface that includes a red 5-digit LED display and a vacuum fluorescent display, driven by microprocessor electronics, that continuously prompts and informs the operator.

• High resolution, accurate readings of concentration from low ppm levels through to 100%. Large, bright, meter readout.

• Versatile analysis over a wide range of applications.

• Microprocessor based electronics: 8-bit CMOS microprocessor with 32 kB RAM and 128 kB ROM.

• Three user definable output ranges (from 0-100 ppm through 0-100 %) allow best match to users process and equipment.

• Calibration range for convenient zeroing or spanning.

• Auto Ranging allows analyzer to automatically select the proper preset range for a given measurement. Manual override allows the user to lock onto a specific range of interest.

• Two adjustable concentration alarms and a system failure alarm.

• Extensive self-diagnostic testing, at startup and on demand, with continuous power-supply monitoring.

• RS-232 serial digital port for use with a computer or other digital communication device.

• Analog outputs for concentration and range identification. (0-1 V dc standard, and isolated 4–20 mA dc)

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• Superior accuracy.

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Photometric Analyzer Introduction 1

1.4 General

A dual channel electro optical infrared analyzer is utilized to continuously monitor either percentage or Part Per Million (PPM) concentrations of the gas of interest. Measurements are displayed on integral digital display. The system is insensitive to the thermal, spectral interference, contamination and zero drift problems normally associated with systems employing IR photometers.

Sample preparation requirements are absolutely minimal and entail only cooling and the automatic removal of heavier particles. Drying of the sample is unnecessary provided no condensation can occur for ambient and sample temperatures and pressures.. The system is simple, cost effective, and contains no critical orifices, sample blending, or processing that might contribute to increased maintenance and system downtime.

Additional features include direct reading linear output and an electronic automatic zero that compensates for analyzer drift over a period of time.

1.5 NDIR Analyzer

The analyzer is a non-dispersive infrared (NDIR) gas analyzer measuring the concentration of one gas of interest in a multicomponent gas mixture. The measurement is accomplished by the infrared absorption of the desired component in the mixture.

Basically, the analyzer consists of an optical unit for gas analysis and an output Control Unit. The simplicity of construction of the overall analyzer makes it one of the most advanced in the industry.

The optical unit contains an infrared energy dual element source, an optical chopper, measurement and reference tubes, optical filter and detector. The detection circuitry is mounted on its own printed circuit board for convenient servicing and signal tracing. Test points have been provided at major points required for adjustment and calibration.

Linearization is accomplished through software providing a linear output voltage and/or current with the full scale range of the interest gas concentration. Circuitry necessary to drive the display and to provide voltage and/or current outputs for external recorders or indicators is located in the control Unit. Software timer used, for automatically zeroing the analyzer, can be programmed on the front panel.

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1 Introduction Model 7100

1-4

7120 piping schematic (typical)

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Photometric Analyzer Installation 2

2.0 Installation

Installation of the Model 7120 Infrared Gas Analyzer includes:

1. Unpacking

2. Mounting

3. Gas connections

4. Electrical connections

5. Testing the system.

2.1 Unpacking the Analyzer/Inspection

The analyzer is shipped with all the materials you need to install and prepare the system for operation. Carefully unpack the analyzer and inspect it for damage. Immediately report any damage to the shipping agent.

2.2 Installing and Connecting the Analyzer

The 7120 analyzer is explosion proof and designed for bulkhead mounting in hazardous environments. It must be installed in an area where the ambient temperature is not permitted to drop below 32°F nor rise above 100°F. In areas outside these temperatures, auxillary heating/cooling must be supplied. The 7120 enclosure is oil and dust resistant though designed to resist moisture. Mounting to walls or racks must be made securely. Avoid locations that are subject to extreme vibration and sway.

Sufficient space must be provided around the analyzer to accommodate the necessary electrical conduit and plumbing connections. The front door must be allowed to pull out for possible service access to all components of the enclosure. Refer to the system/analyzer outline drawings for dimensions.

Regardless of configuration, the analyzer/system must be installed on a level surface with sufficient space allocated on either side for personnel and test equipment access. Subject to the foregoing, the Analyzer/System should be placed as close to the sample point as possible and bolted to its supporting

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surface. When installed as a system with enclosure (non-panel or rack mounted) a waterproof mastic should be liberally applied to the under surfaces of all supporting legs of the cubicle system before placing it in position and bolting it in place. Do allow enough space in front of the enclosure to swing the door open (a 16 1/4 radius as shown on Fig. 2-1).

Figure 2-1: Required Front Door Clearance

2.2.1 User Connections

All user connections are made via cables which enter the explosion-proof housing through ports on its side. No conduit fittings are supplied. The installer must provide two 3/4” NPT and two 1” NPT adapters and the appropriate sealing conduit.

2.2.2 Electrical Power Connections

The standard power requires a supply of 100-125VAC, single-phase power. Power connections are made inside the alalyzer at the properly labeled strip terminal. Refer to the input-output diagram for more information. The electrical power service must include a high-quality ground wire. A highquality ground wire is a wire that has zero potential difference when measured to the power line neutral. 220 or 240 VAC, 50/60 Hz power is optional. Check the analyzer input-output diagram, power schematic, outline, and wiring diagrams for incoming power specifications and connecting points.

Warning: Primary power to the system should not be supplied until all customer wiring is inspected properly by start-up personnel.

as zero gas.

2-2

2.2.3 Calibration Gases

The system may require a supply of clean, oil and particulate free air for use

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Photometric Analyzer Installation 2

For accurate calibration, the analyzer requires a blended gas mixture, typically 80-90% of the full scale range. For examle: a 0-1% CO analyzer, should use a 0.8 to 0.9% CO in N2 bottled mixture. The gas blend should be a working certified standard, analyzed by the gas supplier to at least 2% accuracy.

Do not restrict the bypass, sample or reference vents of the analyzer (and sample system when provided). All lines must vent to a stable safe area-typically 1 ATM A +/- 0.005 pressure (0 psig +/- 0.07). Be sure to vent the analyzer exit to atmospheric unless otherwise indicated by the system piping schematic. Refer to the systsem outline, piping schematics for proper connections and flow paths of the analysis system.

2.2.4 Pipe Connections

Refer to Appendix Piping Drawings for information about pipe connections. On special systems, consult the text in the manual that describes your particular sample system in detail.

2.2.5 Sample Delivery System

The sample delivery system should be designed to operate reliably and must be of large enough capacity to avoid flow stops. A pump is required only if there is insufficient pressure to reliably supply the sample to the system equipment panel. Do not complicate the delivery system by adding a pump unless it is absolutely necessary. If a pump is required, select a type that can handle the sample (corrosion), as well as meet the area classification and Environmental conditions.

2.2.6 Venting the System

In gas analysis systems, the system vent manifold or bypass/sample vents must terminate in a safe area as the sample may be poisonous, corrosive or flammable.

2.3 Electrical Connections

Figure 2-2 shows the Model 7120 interface panel. There are connectors for power, digital communications, and both digital and analog concentration output.

For safe connections, no uninsulated wiring should be able to come in contact with fingers, tools or clothing during normal operation.

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CAUTION: Use Shielded Cables. Also, use plugs that provide

excellent EMI/RFI protection. The plug case must be connected to the cable shield, and it must be tightly fastened to the analyzer with its fastening screws. Ultimately, it is the installer who ensures that the connections provide adequate EMI/RFI shielding.

2.3.1 Primary Input Power

The power strip is located at the interface panel iside the analyzer.

DANGER: POWER IS APPLIED TO THE INSTRUMENT'S CIR-

CUITRY AS LONG AS THE INSTRUMENT IS CONNECTED TO THE POWER SOURCE. THE STANDBY FEATURE ON THE FRONT PANEL IS FOR SWITCHING POWER ON OR OFF TO THE DISPLAYS AND OUTPUTS ONLY.

The standard power supply requires a 110 VAC, 50-60 Hz power

source. 220 VAC, 50-60 Hz power-optional.

2.3.2 Fuse Installation

The fuse block, at the right of the power cord receptacle is 2A for 115VAC or 1A for 115VAC. Be sure to install the proper fuse as part of installation.

2.3.3 Terminal Block Connections

Figure 2-2 shows the terminal block layout of the Equipment Interface panel. The arrangement is shown as seen when the viewer faces the interface panel from the front of the analyzer.

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Photometric Analyzer Installation 2

FUSE

Figure 2-2: Analog Output Connections

2.3.3.1 Analog Outputs

There are four DC output signal pins—two pins per output. For polar-

ity, see Figure 2-3. The outputs are: 0–1 V dc % of Range: Voltage rises linearly with increasing concentration,

from 0 V at 0 concentration to 1 V at full scale. (Full scale = 100% of programmable range.)

0–1 V dc Range ID: 0.25 V = Range 1, 0.5 V = Range 2, 0.75 V =

Range 3, 1 V = Cal Range.

4–20 mA dc % Range: Current rises linearly with concentration, from 4

mA at 0 concentration to 20 mA at full scale. (Full scale = 100% of programmable range.)

4–20 mA dc Range ID: 8 mA = Range 1, 12 mA = Range 2, 16 mA =

Range 3, 20 mA = Range 4.

Figure 2-3: Analog Output Connections

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Current Optional

Floating

CURRENT

++++

VOLTAGE

Negative ground

Insert wire here.

Press here to insert wire. Release to hold.

4-20mA O/P % RANGE

4-20mA O/P RANGE ID

0-1 V O/P % RANGE

0-1 V O/P RANGE ID

The analog output signal has a voltage which depends on gas concentration relative to the full scale of the range. To relate the signal output to the actual concentration, it is necessary to know what range the instrument is currently on, especially when the analyzer is in the autoranging mode.

The signal output for concentration is linear over the currently selected analysis range. For example, if the analyzer is set on a range that was defined

Examples:

The signal output for concentration is linear over the currently selected analysis range. For example, if the analyzer is set on a range that was defined as 0–10 % hydrogen, then the output would be as shown in Table 2-3.

Table 2-3: Analog Concentration Output—Example

Percent Voltage Signal Current Signal

CO Output (V dc) Output (mA dc)

0 0.0 4.0 1 0.1 5.6

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Photometric Analyzer Installation 2

2 0.2 7.2 3 0.3 8.8 4 0.4 10.4 5 0.5 12.0 6 0.6 13.6 7 0.7 15.2 8 0.8 16.8 9 0.9 18.4

10 1.0 20.0

To provide an indication of the range, the Range ID analog outputs are used. They generate a steady preset voltage (or current when using the current outputs) to represent a particular range. Table 2-4 gives the range ID output for each analysis range.

Table 2-4: Analog Range ID Output—Example

Range Voltage (V) Current (mA) Application

Range 1 0.25 8 90-100% CO/N Range 2 0.50 12 95-100% CO/N Range 3 0.75 16 0-100% CO/N Range 4 (Cal) 1.00 20 98-100% CO2/N

2.3.3.2 Alarm Relays

The nine alarm-circuit connector pins connect to the internal alarm relay contacts. Each set of three pins provides one set of Form C relay contacts. Each relay has both normally open and normally closed contact connections. The contact connections are shown in Figure 2-4. They are capable of switching up to 3 amperes at 250 V ac into a resistive load. The connectors are:

Threshold Alarm 1: • Can be configured as high (actuates when concen-

tration is above threshold), or low (actuates when concentration is below threshold).

• Can be configured as failsafe or nonfailsafe.

• Can be configured as latching or nonlatching.

• Can be configured out (defeated).

Threshold Alarm 2: • Can be configured as high (actuates when concen-

tration is above threshold), or low (actuates when

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concentration is below threshold).

• Can be configured as failsafe or nonfailsafe.

• Can be configured as latching or nonlatching.

• Can be configured out (defeated).

System Alarm: Actuates when DC power supplied to circuits is

unacceptable in one or more parameters. Permanently configured as failsafe and latching. Cannot be defeated. Actuates if self test fails.

(Reset by pressing button to remove power. Then press again and any other button EXCEPT System to resume.

Further detail can be found in chapter 4, section 4-5.concentration is

below threshold).

• Can be configured as failsafe or nonfailsafe.

• Can be configured as latching or nonlatching.

• Can be configured out (defeated). System Alarm: Actuates when DC power supplied to circuits is

unacceptable in one or more parameters. Permanently configured as failsafe and latching. Cannot be defeated. Actuates if self test fails.

(Reset by pressing button to remove power. Then press again and any other button EXCEPT System to resume.

Further detail can be found in chapter 4, section 4-5.

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Photometric Analyzer Installation 2

Figure 2-4: Alarm Relay Contact Pins

Normally open Normally closed

Moving contact

Insert wire here.

Press here to insert wire. Release to hold.

THRESHOLD

ALARM 1

Remote Calibration Protocol: To properly time the Digital Remote Cal Inputs to the Model 7120 Analyzer, the customer's controller must monitor the Cal Relay Contact.

When the contact is OPEN, the analyzer is analyzing, the Remote Cal Inputs are being polled, and a zero or span command can be sent.

When the contact is CLOSED, the analyzer is already calibrating. It will ignore your request to calibrate, and it will not remember that request.

Once a zero or span command is sent, and acknowledged (contact closes), release it. If the command is continued until after the zero or span is complete, the calibration will repeat and the Cal Relay Contact (CRC) will close again.

For example:

1) Test the CRC. When the CRC is open, Send a zero command until the CRC closes (The CRC will close quickly.)

2) When the CRC closes, remove the zero command.

3) When CRC opens again, send a span command until the CRC closes. (The CRC will close quickly.)

4) When the CRC closes, remove the span command.

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When CRC opens again, zero and span are done, and the sample is

being analyzed.

Note: The Remote Probe connector provides signals to operate the

zero and span gas valves synchronously. However, if you have the –C Internal valve option, which includes zero and span gas inputs, the 7120 automatically regulates the zero, span and sample gas flow.

2.3.3.4 Range ID Relays

Four dedicated Range ID relay contacts. For any single application they are assigned to relays in ascending order. For example: if all ranges have the same application, then the lowest range is assigned to the Range 1 ID relay, and the highest range is assigned to the Range 3 ID relay. Range 4 is the Cal Range ID relay. Figure 2-6 lists the pin connections.

Table 2-6: Remote Calibration Connections

Pin Function

9 + Remote Zero 11 – Remote Zero 10 + Remote Span 12 – Remote Span 40 Cal Contact 41 Cal Contact

Remote Calibration Protocol: To properly time the Digital Remote

Cal Inputs to the Model 7120 Analyzer, the customer's controller must monitor the Cal Relay Contact.

When the contact is OPEN, the analyzer is analyzing, the Remote Cal

Inputs are being polled, and a zero or span command can be sent.

When the contact is CLOSED, the analyzer is already calibrating. It

will ignore your request to calibrate, and it will not remember that request.

2-10

For example:

1) Test the CRC. When the CRC is open, Send a zero command until the CRC closes (The CRC will close quickly.)

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Photometric Analyzer Installation 2

2) When the CRC closes, remove the zero command.

3) When CRC opens again, send a span command until the CRC closes. (The CRC will close quickly.)

4) When the CRC closes, remove the span command.

When CRC opens again, zero and span are done, and the sample is

being analyzed.

Note: The Remote Probe connector provides signals to operate the

2.3.3.4 Range ID Relays

Moving contact

Normally open

RANGE 1

CONTACT

Table 2-7: Range ID Relay Connections

Pin Function

21 Range 1 ID Contact 38 Range 1 ID Contact 22 Range 2 ID Contact

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39 Range 2 ID Contact 19 Range 3 ID Contact 18 Range 3 ID Contact 34 Range 4 ID Contact 35 Range 4 ID Contact

2.3.3.5 Network I/O

A serial digital input/output for local network protocol. At this printing, this port is not yet functional. It is to be used in future options to the instrument.

2.3.3.6 Remote Valve Connector

The 7120 is a single-chassis instrument, which has no Remote Probe Unit. Instead, the Remote Valve connector is used as another method for controlling external sample/zero/span gas valves. See Figure 2-7.

Figure 2-7: Remote Probe Connector Pinouts

The voltage from these outputs is nominally 0 V for the OFF and 15 V dc for the ON conditions. The maximum combined current that can be pulled from these output lines is 100 mA. (If two lines are ON at the same time, each must be limited to 50 mA, etc.) If more current and/or a different voltage is required, use a relay, power amplifier, or other matching circuitry to provide the actual driving current.

In addition, each individual line has a series FET with a nominal ON resistance of 5 ohms (9 ohms worst case). This could limit the obtainable voltage, depending on the load impedance applied. See Figure 2-8.

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Figure 2-8: FET Series Resistance

2.3.4 RS-232 Port

The digital signal output is a standard RS-232 serial communications port used to connect the analyzer to a computer, terminal, or other digital device. It requires a standard 9-pin D connector.

Output: The data output is status information, in digital form, updated every two seconds. Status is reported in the following order:

• The concentration in ppm or percent

• The range in use (00 = Range 1, 01 = Range 2, 10 = Range 3, 11 = Range 4)

• The span of the range (0-100 %, etc)

• Which alarms—if any—are disabled (AL–x DISABLED)

• Which alarms—if any—are tripped (AL–x ON).

Each status output is followed by a carriage return and line feed.

Input: The input functions using RS-232 that have been implemented

to date are described in Table 2-3.

Table 2-8: Commands via RS-232 Input

Command Description as<enter> Immediately starts an autospan. az<enter> Immediately starts an autozero. rp<enter> Allows reprogramming of two System functions:

APPLICATION (gas use) and ALGORITHM (linearization).

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st<enter> Toggling input. Stops/Starts any status message output from

the RS-232, until st<enter> is sent again.

Implementation: The RS-232 protocol allows some flexibility in its

implementation. Table 2-9 lists certain RS-232 values that are required by the Model 7120 implementation.

Table 2-9: Required RS-232 Options

Parameter Setting

Baud 2400

Byte 8 bits

Parity none

Stop Bits 1

Message Interval 2 seconds

2.4 Gas Requirements

Instrument Air is required for zeroing of the Infrared Analyzer. It must

be free of oil, particulates and water vapor (that will not condensate, unfiltered plant air is not recommended). A supply pressure of 10100psig with a typical flow rate of 2 scfh (1 lpm) is needed. Bottled gas is recommended (air or Nitrogen) if high quality air is not available.

For accurate calibration, the analyzer requires blended gas mixtures

certified to +/- 2% accuracy.

2.5 Testing the System

Before plugging the instrument into the power source:

• Check the integrity and accuracy of the fluid connections. Make sure there are no leaks.

• Check the integrity and accuracy of the electrical connections. Make sure there are no exposed conductors

• Check that sample pressure is controlled accuracately and is maintained between 0 to 10 psig, according to the requirements of your process.

operations:

2-14

NOTE: Special designed systems may require checks under vacuum

or high pressure (consult manual addendum).

Power up the system, and test it by performing the following

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Photometric Analyzer Installation 2

1. Repeat the Self-Diagnostic Test, section 5.2

2.6 Calibration

2.6.1 Calibration Fluids

Zero and span fluids must be made by the chemistry lab or certified zero and span gas bought from a gas supplier. The zero fluid must be the major component of the sample, free from the component of interest. In purity applications, the accuracy is only as good as the purity of the zero gas used to reference to. The 7120 has a continuous flowing optical reference gas path that the sample is compared to, so it must be very pure, i.e, CO2 purity of 99.995%. Typically this reference flow is about 20 ccm.

Note: In Non-purity applications, the reference cell may be sealed

with clean air (consult factory).

The span fluid must be the major component of the sample mixed with a small amount of the component of interest. The concentration must be 80 to 95% of the full scale range or the widest range of the instrument (if the instrument provides more than one range). (i.e, for a 98-100% CO2 range purity, use span of 98.40% N2 in 99.995% pure CO2).

2.6.2 Calibration

Refer to Section 4.4 of the manual to determine how to manipulate the mode setting. The recommended calibration method is as follows:

1. Calibration with zero and span fluids. (Note: Zero gas may be 100% gas

in purity applications).

Method:

1. Introduce zero fluid and set zero as referred in section 4.4.1

NOTE: When calibrating from 0% to an upper concentration gas, obtain a zero gas (minus the analyte) that typically is as pure as the minimum resolution needed to control to. This usually meets or exceeds the minimum full scale accuracy of the measurement.

2. Introduce a span fluid and set the concentration of the span fluid. Refer to the span procedure in section 4.4.2. (Note: The span gas should typically be an 80% of full scale range gas similar to the 100% zero gas background; i.e., 100% CO2 zero gas and a span gas of 98.4% CO2 in N2 for a 98-100%CO2 purity application.

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Photometric Analyzer Start-up and Operation

3.0 Start-up and Operation

3.1 Preliminary

Before applying power to the system, TAI suggests that the electrical wiring installation be checked against the system input-output diagram. Proper attention to this preliminary check will prevent severe damage caused by wiring errors.

Also, verify that all connections to the system have been made correctly. Refer to the system outline diagram for proper connections.

3.2 NDIR Analyzer Startup

Power up the unit by depressing the rear panel switch. From a first time power-on cold start attempt, allow (1) one hour warm-up to proceed. Observe that the Digital display will go through a diagnostic routine before the readings revert to a continuous concentration readout.

3.2.1 Initial Set-up and Zeroing

Assure the sample will enter from the zero inlet gas position. Open the zero gas tank and set the pressure regulator to 20 psig. Set the zero gas flow to 2 SCFH (1 lpm). Set the sample flow to 2 SCFH (1 lpm). When applicable, assume the flowing reference cell gas is flowing between 20-50 ccm.

Initialize a zero operation through the system menu. Refer to Section 4 for Electronics /Control Unit Modes and Functioning to navigate the zero menu.

After the zero cycle is over, the instrument is automatically brought in the sampling cycle. An inaccurate reading of the concentration of the gas of interest will be obtained. The instrument is not yet calibrated. Permit the instrument to operate in this mode for at least one hour to stabilize if not already done so upon initial power up.

NOTE: The following options could be included in your system:

In case the instrument is part of a multi instrument system, where all instruments are connected to the same sample system and under control of a single timer, all instruments of the system will go through the zero and sample cycle simultaneously. The Control Unit of the instrument which

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3 Start-up and Theory of Operation Model 7120

houses the timer and operates the sampling system is called the master. The other Control Units of the other instruments are called slaves.

Each of the other instruments may be monitoring the concentration of several different gases of interest in the sample, for example CO, CO2 and/or Combustibles as CH4 in flue gas.

3.2.2 Operational Calibration

After the instrument has stabilized, let zero gas flow through the

analyzer

Perform a zero of the analyzer. Perform a span of the analyzer.

Open the span gas tank and set the pressure regulator to 20 psig. Switch the mode switch to sample. Refer to Section 4 again. Induce an automatic zero cycle as described in Section 4 also.

After the zero cycle, the analyzer reverts to the sample cycle. The sample reading is now accurate and the analyzer is placed in continuous operation. See Sections 4.6-4.8.

NOTE: In case slave analyzers are involved, calibrate them simultaneously with the master analyzer.

After the instrument is calibrated, when no Auto-Cal option was selected, shut off the main valve on the span gas tank. This tank is not used during automatic sampling. Leave the zero tank open.

3.3 Theory of operation

3.3.1 General

The non-dispersive infrared (NDIR) analyzer is one of the major components

of the system. It employs the basic principles of spectroscopic analysis to measure a specific concentration of one gas in a multicomponent gas system. The concentration of a gas is determined by exposing a chamber filled with a gas mixture to infrared radiant energy and measuring how much of the specific (non-dispersive) infrared wavelength is absorbed by the gas being measured.

As an example, the NDIR analyzer is used most in flue gas applications where the amount of carbon monoxide in a flue gas mixture is measured. The specific infrared wavelength at which the carbon monoxide molecule absorbs infrared energy is at 4.65 microns. The more carbon monoxide present in the measurement cell, the more energy its molecules absorb.

The NDIR analyzer needs four basic components to measure the spectral

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