Teledyne 4020 User Manual

Total Hydrocarbon Analyzer

INSTRUCTION, OPERATING, AND

MAINTENANCE MANUAL FOR

MODEL 4020

Standard Software Version

P/N M74661

4/05/2010 Rev 6

DANGER

Toxic and/or flammable gases or liquids may be present in this monitoring system.
Personal protective equipment may be required when servicing this instrument.
Hazardous voltages exist on certain components internally which may persist for

a time even after the power is turned off and disconnected.
Only authorized personnel should conduct maintenance and/or servicing. Before

conducting any maintenance or servicing, consult with authorized
supervisor/manager.

Teledyne Analytical Instruments i

Model 4020

Copyright © 2010 Teledyne Analytical Instruments

All Rights Reserved. No part of this manual may be reproduced, transmitted, transcribed,
stored in a retrieval system, or translated into any other language or computer language in
whole or in part, in any form or by any means, whether it be electronic, mechanical,
magnetic, optical, manual, or otherwise, without the prior written consent of Teledyne
Analytical Instruments, 16830 Chestnut Street, City of Industry, CA 91749-1580.

Warranty

This equipment is sold subject to the mutual agreement that it is warranted by us free from
defects of material and of construction, and that our liability shall be limited to replacing or
repairing at our factory (without charge, except for transportation), or at customer plant at
our option, any material or construction in which defects become apparent within one year
from the date of shipment, except in cases where quotations or acknowledgements provide
for a shorter period. Components manufactured by others bear the warranty of their
manufacturer. This warranty does not cover defects caused by wear, accident, misuse,
neglect or repairs other than those performed by Teledyne or an authorized service center.
We assume no liability for direct or indirect damages of any kind and the purchaser by the
acceptance of the equipment will assume all liability for any damage which may result from
its use or misuse.

We reserve the right to employ any suitable material in the manufacture of our apparatus,
and to make any alterations in the dimensions, shape or weight of any parts, in so far as
such alterations do not adversely affect our warranty.

Important Notice

This instrument provides measurement readings to its user, an d serves as a to ol by whic h
valuable data can be gathered. The information provided by the instrument may assist the user
in eliminating potential hazards caused by his process; however, it is essential that all
personnel involved in the use of the instrument or its interface be properly trained in the
process being measured, as well as all instrumentation related to it.

The safety of personnel is ultimately the responsibility of those who control process
conditions. While this instrument may be able to provide early warning of imminent
danger, it has no control over process conditions, and it can be misused. In particular, any
alarm or control systems installed must be tested and understood, both as to how they
operate and as to how they can be defeated. Any safeguards required such as locks, labels,
or redundancy, must be provided by the user or specifically requested of Teledyne at the
time the order is placed.

Therefore, the purchaser must be aware of the hazardous process conditions. The purchaser
is responsible for the training of personnel, for providing hazard warning methods and
instrumentation per the appropriate standards, and for ensuring that hazard warning devices
and instrumentation are maintained and operated properly.

Teledyne Analytical Instruments, the manufacturer of this instrument, cannot accept
responsibility for conditions beyond its knowledge and control. No statement expressed or
implied by this document or any information disseminated by the manufacturer or its
agents, is to be construed as a warranty of adequate safety control under the user’s process
conditions.

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Total Hydrocarbon Analyzer

Specific Model Information

The instrument for which this manual was supplied may incorporate
one or more options not supplied in the standard instrument. Commonly
available options are listed below, with check boxes. Any that are
incorporated in the instrument for which this manual is supplied are
indicated by a check mark in the box.

Instrument Serial Number: _______________________

Options Included in the Instrument with the Above Serial Number:

 Power Requirements: This instrument may be designed for

operation using a power source other than 115 VAC @ 60
Hz. If so, one of the boxes below will be checked indicating
the power requirements for your instrument.

 110 VAC @ 50 Hz
 115 VAC @ 50 Hz
 220 VAC @ 50/60 Hz
 Other: _______________

 Using Hydrogen as Sample: For applications where the

sample gas is hydrogen, the sample gas doubles as the fuel
for combustion. The gas connections made at the back panel
are slightly different for this configuration. Connect the
hydrogen sample gas to the sample input as usual. Connect a
nitrogen source at 40 psig to the fuel input. This is discussed
in the manual in the Installation section.

 Using Hydrogen as Fuel: For applications where the fuel is

hydrogen, the gas connections made at the back panel are

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Model 4020

slightly different. At the “FUEL” inlet, replace the “40%
H

/60% N2” with pure H2. This is discussed in the

2

Installation section.

 Special Analysis Ranges: this model 4020 has special

analysis ranges:
Range 1: ___________
Range 2: ___________
Range 3: ___________

 Auto-Calibration Module Option: This module consists of

solenoid for automatically selecting calibration or sample
flow to the analyzer and provides the user with the ability to
calibrate the analyzer on a user-programmed schedule.

 AP Options: Vented Sample System Covers; Perforated

covers have been installed over the sample system
compartment and analyzer top cover for venting purposes.

 Recommended warm-up period: hours
 Other:

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Total Hydrocarbon Analyzer

Safety Messages

Your safety and the safety of others is very important. We have
provided many important safety messages in this manual. Please read
these messages carefully.

A safety message alerts you to potential hazards that could hurt you
or others. Each safety message is associated with a safety alert symbol.
These symbols are found in the manual and inside the instrument. The
definition of these symbols is described below:

GENERAL WARNING/CAUTION: Refer to the
instructions for details on the specific danger. These
cautions warn of specific procedures which if not
followed could cause bodily Injury and/or damage the
instrument.

No

Symbol

CAUTION: HOT SURFACE WARNING: This warning is
specific to heated components within the instrument.
Failure to heed the warning could result in serious burns
to skin and underlying tissue.

WARNING: ELECTRICAL SHOCK HAZARD: Dangerous
voltages appear within this instrument. This warning is
specific to an electrical hazard existing at or nearby the
component or procedure under discussion. Failure to heed
this warning could result in injury and/or death from
electrocution.

Technician Symbol: All operations marked with this
symbol are to be performed by qualified maintenance
personnel only.

NOTE: Additional information and comments regarding
a specific component or procedure are highlighted in the
form of a note.

STAND-BY: This symbol indicates that the instrument is
on Stand-by but circuits are active.

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Model 4020

CAUTION: THE ANALYZER SHOULD ONLY BE USED FOR THE

PURPOSE AND IN THE MANNER DESCRIBED IN
THIS MANUAL.

IF YOU USE THE ANALYZER IN A MANNER OTHER
THAN THAT FOR WHICH IT WAS INTENDED,
UNPREDICTABLE BEHAVIOR COULD RESULT
POSSIBLY ACCOMPANIED WITH HAZARDOUS
CONSEQUENCES.

This manual provides information designed to guide you through the
installation, calibration and operation of your new analyzer. Please read
this manual and keep it available.

Occasionally, some instruments are customized for a particular
application or features and/or options added per customer requests.
Please check the front of this manual for any additional information in
the form of an Addendum which discusses specific information,
procedures, cautions and warnings that may be specific to your
instrument.

Manuals do get misplaced. Additional manuals can be obtained from
Teledyne at the address given in the Appendix. Some of our manuals are
available in electronic form via the internet. Please visit our website at:
www.teledyne-ai.com.

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Total Hydrocarbon Analyzer

Table of Contents

Safety Messages ........................................................................... v

List of Figures ............................................................................... xi

List of Tables ............................................................................... xii

Additional Safety Information .................................................. xiii

Procedure for Removal of Internal Inaccessible Shock Hazards xv

Introduction ................................................................................... 1

1.1 Main Features of the Analyzer 1

1.2 Principle of Operation 2

1.3 Analyzer Description 2

1.4 Applications 3

Operational Theory ....................................................................... 7

2.1 Introduction 7

2.2 Sample System 7

2.2.1 Input Porting 8

2.2.2 Sample Flow Control System 8

2.2.3 Fuel and Blanket Air Systems 8

2.2.4 Flame Ionization Detection Cell 9

2.3 Detection Cell 9

2.3.1 Electrometer-Amplifier 10

2.3.2 Anode Power Supply 11

2.3.3 Flame Guard Circuit 11

2.3.4 Flame Ignition Circuit 11

2.3.5 Proportional Temperature Control Circuit 11

Installation ................................................................................... 13

3.1 Unpacking the Analyzer 13

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Model 4020

3.2 Mounting the Analyzer 13

3.3 User Connections 14

3.3.1 Electrical Power Connections 14

3.3.2 Gas Connections 14

3.3.2.1 Vent Connections 16

3.3.3 Electrical Connections 16

3.3.3.1 Primary Input Power 17

3.3.3.2 Fuse Installation 17

3.3.3.3 50-Pin Equipment Interface Connector 17

3.3.3.4 Analog Output 18

3.3.3.5 Alarm Relays 20

3.3.3.6 Digital Remote Cal Inputs 21

3.3.3.7 Range ID Relays 23

3.3.3.8 Network I/O 23

3.3.3.9 Pin Out Table 23

3.3.4 RS-232 Port 25

3.3.5 Supporting Gases 26

3.3.5.1 Sample Gas 27

3.3.5.2 Effluent 27

3.3.5.3 Sample Bypass Vent 27

3.3.5.4 Fuel and Air Connections 27

Operation ..................................................................................... 29

4.1 Equipment 29

4.2 Preliminary Power-Off Check List 30

4.3 Placing the System in Operation 30

4.4 Activating the Support Gases 31

4.4.1 Air 31

4.4.2 Sample Gas 31

4.4.3 Span Gas 31

4.4.4 Fuel 31

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4.5 Flame Ignition 32

4.5.1 Verification of the Flame Guard Circuit 32

4.5.2 Ignition and/or Flame Guard Circuit Failure 33

4.6 Analyzer Operation 33

4.6.1 Default Parameters 34

4.6.2 Style Conventions 34

4.6.3 Using the Controls 35

4.6.4 Mode/Function Selection 35

4.6.4.1 Analysis Mode 36

4.6.4.2 Setup Mode 37

4.6.5 Data Entry 38

4.6.5.1 ENTER 38

4.6.5.2 ESCAPE 38

4.6.6 Setting up an AUTO-CAL 40

4.6.7 Password Protection 42

4.6.7.1 Entering the Password 43

4.6.7.2 Installing or Changing the Password 44

4.6.8 Logging Out 45

4.6.9 System Self-Diagnostic Test 45

4.6.10 The Model Screen 46

4.6.11 Zero and Span Functions 47

4.6.12 The Alarms Function 50

4.6.13 The Range Function 53

4.6.13.1 Manual (Select/Define Range) Screen 53

4.6.13.2 Auto Range 55

4.6.13.3 Digital Mode 56

4.6.14 Digital Filter Setup 57

4.6.15 Fuel Display 58

4.6.16 Valve Selections 58

4.6.16.1 Disabled 59

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Model 4020

4.6.16.2 User Select 59

4.6.16.3 Default (By Function) 61

4.6.16.4 Observing the gas Stream Concentrations 62

4.6.17 Standby 63

4.7 Advanced User Functions 63

4.7.1 Zero Offset Adjustment 64

4.7.2 Background Gas Selection 65

Maintenance & Troubleshooting ................................................ 67

5.1 Measuring Circuit Electrical Checks 68

5.1.1 Loss of Zero Control 68

5.1.2 Anode Voltage Check 69

5.1.3 Electronic Stability 70

5.1.4 Printed Circuit Board Replacement 70

5.1.5 Collector Cable 70

5.2 Temperature Control Electronic Check 71

5.3 Ignition and/or Flame Guard Circuit Checks 72

5.4 Sampling System 73

5.5 Printed Circuit Board Descriptions 73

5.5.1 Flame Guard and Anode Power Supply PCB 73

5.5.3 Proportional Temperature Controller PCB 74

5.5.4 Electrometer-Amplifier PCB 76

Appendix ...................................................................................... 79

Specifications 79
Application Data 80
Recommended Spare Parts List 81
Drawing List 82

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Total Hydrocarbon Analyzer

List of Figures

Figure 1-1: Gas Sample System with Optional AutoCal Valves ...... 4

Figure 1-2: Gas Sample System Without Optional AutoCal Valves . 5

Figure 1-3: Flame Ionization Cell ..................................................... 6

Figure 2-1: View Inside Cabinet .................................................... 10

Figure 3-1: Gas Connections ......................................................... 15

Figure 3-2: Equipment Interface Connector Pin Arrangement ....... 18

Figure 4-1: Front Panel View of Regulator and Gages .................. 32

Figure 4-2: Typical VFD Screen Layout ........................................ 35

Figure 4-3: Setup Mode Functions ................................................ 39

Figure 4-4: AUTOCAL Screens ..................................................... 42

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Model 4020

List of Tables

Table 3-1: Analog Output Connections ......................................... 18

Table 3-2: Analog Concentration Output—Example ...................... 19

Table 3-3: Analog Range ID Output—Example ............................. 20

Table 3-4: Alarm Relay Contact Pins ............................................ 21

Table 3-5: Remote Calibration Connections .................................. 22

Table 3-6: Range ID Relay Connections ....................................... 23

Table 3-7: Pin out of 50 pin D-Sub Connector ............................... 24

Table 3-8: Commands via RS-232 Input ....................................... 26

Table 3-9: Required RS-232 Options ............................................ 26

Table 4-1: Digital Range Selection Signals ................................... 56

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Total Hydrocarbon Analyzer

Additional Safety Information

DANGER

COMBUSTIBLE GAS USAGE

This is a general purpose instrument designed for usage in a
non-hazardous area. It is the customer's responsibility to
ensure safety especially when combustible gases are being
analyzed since the potential of gas leaks always exist.

WARNING

The customer should ensure that the principles of operating
of this equipment are well understood by the user. Misuse of
this product in any manner, tampering with its components,
or unauthorized substitution of any component may
adversely affect the safety of this instrument.

Since the use of this instrument is beyond the control of
Teledyne, no responsibility by Teledyne, its affiliates, and
agents for damage or injury from misuse or neglect of this
equipment is implied or assumed.

WARNING: HYDROGEN GAS IS USED IN THIS INSTRUMENT AS

A FUEL. HYDROGEN IS EXTREMELY FLAMMABLE.
EXTREME CARE MUST BE USED WHEN WORKING
AROUND GAS MIXTURES CONTAINING
FLAMMABLE GASES.

A Successful leak check was performed at TI/AI on
the sample system of this instrument prior to
calibration, testing and shipping. Ensure that there
are no leaks in the fuel supply lines before applying
power to the system.

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Model 4020

Always purge the entire system before performing
any maintenance and always leak check the system
after removing any tubing or fittings on the sample
system. See the procedures for purging and leak
checking this instrument on the following pages.

If toxic gases or other hazardous materials are
introduced into the sample system, the same
precautions regarding leak checking and purging
apply to the sample lines and sample supply or
delivery lines.

WARNING: ELECTRICAL SHOCK HAZARD. WITH THE

EXCEPTION OF OPENING THE DOOR AND
ADJUSTING THE PRESSURE REGULATORS, FLOW
CONTROLLER, OR OBSERVING THE PRESSURE
GAUGES AND THE FLOWMETER, ONLY
AUTHORIZED AND SUITABLY TRAINED
PERSONNEL SHOULD PERFORM WORK INSIDE OF
THE INSTRUMENT. COMPONENTS WITHIN THE
COVER ON THE INSIDE OF THE DOOR, INSIDE THE
ISOTHERMAL CHAMBER (SAMPLE SYSTEM), AND
ON THE ELECTROMETER-AMPLIFIER PC BOARD
CONTAIN DANGEROUSLY HIGH VOLTAGE
SUFFICIENT TO CAUSE SERIOUS INJURY OR
DEATH.

There are the following three types of inaccessible

shock hazards within the 4020:

1. Line voltages and line related voltages such as
115 VAC which exists within the 230 VAC version
as well. These voltages stop when the 4020 is
turned off and the mains (line) cord is removed
from the instrument.

2. The sensor anode supply voltage (approximately
250 VDC). This voltage exists on the Flame
Guard, anode power supply, PCB, the
motherboard, and the anode/igniter terminals on
the sensor. THIS VOLTAGE WILL REMAIN
HAZARDOUS FOR MANY MINUTES AFTER THE
MODEL 4020 HAS BEEN TURNED OFF!

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Total Hydrocarbon Analyzer

3. External hazardous voltages which may be
connected to the Model 4020 alarm relay
connections.

Procedure for Removal of Internal Inaccessible
Shock Hazards

CAUTION: SERVICING OR MAINTENANCE OF THE 4020

SHOULD ONLY BE DONE BY SUITABLE TRAINED
PERSONNEL. TO AVOID THESE INACCESSIBLE
HAZARDOUS VOLTAGES WHEN SERVICING THE
4020, PERFORM EACH OF THE FOLLOWING STEPS,
IN THE ORDER GIVEN, BEFORE SERVICING
BEGINS:

1. Switch off the power to the 4020 and remove the mains (line)

power cord from the 4020.

2. Remove all external voltages from the connections to the

alarm contacts.

3. Wait one minute.

4. Discharge the anode supply voltage.
a. Connect one end of an insulated (to 1000 VDC or more)

clip lead to 4020 chassis ground (the standoff for the
upper right corner of the mother PCB).

b. Put one end of a 500V rated 1000 ohm resistor in the

other end of the clip lead.

c. Check the voltage between chassis ground (the standoff

for the upper right corner of the mother PCB) and the top
side of R2 at PCB number B74671. It should be between

-5VDC and +5VDC. If is in that range, the inaccessible
hazardous voltage removal procedure is completed, if not
repeat steps 4.a and 4.b.

If it is absolutely necessary to work inside the instrument with power

on, use the ONE HAND RULE:

Work with one hand only.

Keep the other hand free without contacting any other object. This
reduces the possibility of a ground path through the body in case of
accidental contact with hazardous voltages.

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Model 4020

WARNING: THIS INSTRUMENT IS DESIGNED TO BE OPERATED

IN A NONHAZARDOUS AREA. THE ANALYZER USES
HYDROGEN GAS AND/OR OTHER COMBUSTIBLE
GASES IN ITS OPERATION. THIS EQUIPMENT, IF
NOT USED AND MAINTAINED PROPERLY CAN BE
AN EXPLOSION HAZARD. THE ANALYZER,
DEPENDING ON THE APPLICATION, MAY ALSO USE
TOXIC GASES. IT IS THEREFORE, THE
CUSTOMER'S RESPONSIBILITY TO ENSURE THAT
PROPER TRAINING AND UNDERSTANDING OF THE
PRINCIPLES OF OPERATION OF THIS EQUIPMENT
ARE UNDERSTOOD BY THE USER. SINCE THE USE
OF THIS INSTRUMENT IS BEYOND THE CONTROL
OF TELEDYNE, NO RESPONSIBILITY BY TELEDYNE,
ITS AFFILIATES AND AGENTS FOR DAMAGE OR
INJURY RESULTING FROM MISUSE OR NEGLECT
OF THIS INSTRUMENT IS IMPLIED OR ASSUMED.
MISUSE OF THIS PRODUCT IN ANY MANNER,
TAMPERING WITH ITS COMPONENTS OR
UNAUTHORIZED SUBSTITUTION OF ANY
COMPONENT MAY ADVERSELY AFFECT THE
SAFETY OF THIS INSTRUMENT.

CAUTION: WHEN OPERATING THIS INSTRUMENT, THE DOORS

MUST BE CLOSED AND ALL COVERS SECURELY
FASTENED. THE GAUGES MUST BE IN PROPER
WORKING ORDER. DO NOT OVERPRESSURIZE THE
SYSTEM.

READ THIS MANUAL BEFORE OPERATING THE

INSTRUMENT AND ADHERE TO ALL WARNINGS
INCLUDED IN THIS MANUAL.

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Total Hydrocarbon Analyzer Introduction

Introduction

Teledyne Analytical Instruments Model 4020 Total Hydrocarbon
Analyzer is a versatile instrument designed to measure the quantity of
hydrocarbons present in a positive pressure sample as equivalent
methane. The Model 4020 is a microprocessor controlled digital
instrument based on Teledyne’s highly successful Model 402R series
analog Total Hydrocarbon Analyzer.

1.1 Main Features of the Analyzer

The Model 4020 Total Hydrocarbon Analyzer is sophisticated yet
simple to use. A dual display on the front panel prompts and informs the
operator during all phases of operation. The main features of the
analyzer include:

 Easy-to-use front panel interface that includes a red 5-digit

LED display and a vacuum fluorescent display (VFD), driven
by microprocessor electronics.

 High resolution, accurate readings of concentration from low

ppm levels to 6%.

 Microprocessor based electronics: 8-bit CMOS

microprocessor with 32 kB RAM and 128 kB ROM.

 Versatile analysis with three user-definable analysis ranges

from 1 ppm through 6%.

 Autoranging 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.

 A digital mode for range selection allows the user to perform

range switching using the remote calibration contacts.

 O2/N2 background gas selection allows the use of two

different sample background gases with separate calibration
parameters stored in memory.

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Introduction Model 4020

 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 VDC standard and isolated 4-20 mA dc).

 Superior Accuracy

1.2 Principle of Operation

The sample gas is mixed with a fuel (normally a composition of
hydrogen and nitrogen) and burned in an atmosphere of “blanket air”.
The ions formed in the burning process cause an electrical conduction
between two electrodes in the combustion chamber (or detector cell) that
is amplified by a highly sensitive electrometer-amplifier circuit. The
electrical output of the electrometer-amplifier is directly proportional to
the quantity of flame ionizable hydrocarbons present, and is linear over
the range of 0-60,000 PPM methane.

1.3 Analyzer Description

The information contained in this manual describes individual analyzers
of the Model 4020 standard series. The versatility of this analyzer is inherited
through the long heritage of the earlier analog unit. Very often, special
customer driven design features are incorporated and will require additional
or supplementary information in addition to the information described in this
manual. These special considerations, if applicable, will be described in detail
on specific application pages as Addenda to this manual. When the Model
4020 is a part of a larger system, it is subordinate to that system, and specific
installation and operation conditions of that system will apply. Consult
system sections of the manuals for those applications, where conditions
specific to those systems will be detailed.

To best suit the needs of the purchaser, specialized designs may have
been adopted. Details of the design differences may be found in the
various drawings (outline, assembly, schematic, wiring, and piping
diagrams) in the drawings section at the rear of the manual.

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Total Hydrocarbon Analyzer Introduction

The standard analyzer is housed in a sheet steel equipment case
flush-mounted in a 19" rack. The front interface panel is mounted on a
door which, when opened, allows convenient access to the 4020
electronics. The entire front panel can slide out of the chassis to provide
greater access to the electronics and to the sample system. Gas pressure
and flow controls are mounted on the front panel adjacent to the LED
and VFD displays and user interface.

At the rear of the instrument are ports for the introduction of air,
fuel, zero, span, and sample gas. A single 50-pin user-interface cable
connector contains input/output and alarm signals available to the user.
An RS-232 port is also available at the rear panel for connection to a
remote computer or other digital communication device. The Model
4020 is set up for either 120 VAC 60 Hz or 230 50/60 Hz operation
depending on the customer’s requirements. The appropriate power cord
for your unit has been shipped with this instrument.

1.4 Applications

 Monitoring the purity of oxygen, argon, nitrogen and other

gases in the manufacture of semiconductors and related
equipment.

 Monitoring hydrocarbon contamination in air liquefaction

and other gas production processes.

 Gas purity certification.
 Detecting trace hydrocarbons in ambient air.
 Detecting atmospheric pollutants.
 Cryogenics.
 Monitoring for fuel leakage or toxic solvents.
 Monitoring hydrocarbons in a wide range of process streams.

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Introduction Model 4020

Figure 1-1: Gas Sample System with Optional AutoCal Valves

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Total Hydrocarbon Analyzer Introduction

Figure 1-2: Gas Sample System Without Optional AutoCal Valves

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Introduction Model 4020

Figure 1-3: Flame Ionization Cell

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Total Hydrocarbon Analyzer Operational Theory

Operational Theory

2.1 Introduction

The Model 4020 Total Hydrocarbon Analyzer is composed of three
subsystems:

1. Sample System

2. Detector Cell

3. Electronic Signal Processing, Display and Control

2.2 Sample System

Note: The measured component for the Model 4020 is

hydrocarbon content. Hydrocarbon lubricants and
conditioners, as well as synthetic plastics are common to
instrumentation supply processes. Utmost precaution must
be taken at all times to specify hydrocarbon-free gases,
regulator diaphragms, and supplies.

All components used to control the sample and supporting gases, as
well as the combustion portion of the detector cell, are located inside the
enclosure, behind the electronics control panel and are accessible by
sliding the front of the unit out from the rack enclosure. Adjustments are
made using the appropriate control on the front panel.

The software in the Model 4020 allows the system to be used for
analyzing a sample gas in two different backgrounds, O
separate calibration must be performed on each sample/background
combination. The calibration parameters are stored internally and are
appropriately applied when the user selects the specific background gas
in use. See Section 4.7.2 Background Gas Selection.

Note: The user must supply the necessary valves and any

associated switching equipment for delivering the correct
sample/background gas combination to the analyzer.

and N2. A

2

Teledyne Analytical Instruments 7

Operational Theory Model 4020

The basic analyzer consists of an isothermal chamber containing the
pressure regulators, pressure gauges and flow restrictors. The
temperature within the chamber is maintained at 125°F by a heating
element. The regulated temperature of the chamber insures stable gas
flow. An optional AutoCal module is available which when fitted,
mounts inside the instrument enclosure and integrates with the sample
system. It allows convenient switching between sample and calibration
gases. When installed, it is part of the isothermal chamber. The bypass
flow is also controlled from this optional panel.

2.2.1 Input Porting

The analyzer is equipped with ports for the introduction of air, fuel,
zero, span, and sample gas.

2.2.2 Sample Flow Control System

Stable sample flow is achieved by maintaining a constant pressure
across a restrictor through the use of a back-pressure regulation system,
which includes an adjustable regulator, pressure gauge, throttle valve,
and flowmeter. The throttle valve and flowmeter are included so that the
bypass flow required by the back-pressure regulator can be limited.
Without these controls, a high sample point pressure would result in
unnecessary sample waste through the back-pressure regulator.

The components of the system are arranged so that no dead volume
is present in the sample path to the detector cell. This guarantees rapid
response to changes in hydrocarbon concentration—a fact that can be
demonstrated when zero and span gas are exchanged during the
standardization procedure.

The restrictors used in the system look alike; however, they are not
interchangeable.

2.2.3 Fuel and Blanket Air Systems

The fuel and blanket air systems use similar components. Stable flow
is achieved by maintaining a constant pressure across restrictors upstream
from the cell. Each system incorporates an adjustable pressure regulator,
pressure gauge, and restrictor. A flame out light is included to indicate
when the flame fails. A fuel shut-off solenoid valve, mounted on the line
that supplies fuel, stops the fuel flow in case of flame failure. This valve is
located in line with the fuel port; except for instruments using hydrogen as
the sample gas. In this case, the sample is used as fuel and the valve is

Teledyne Analytical Instruments 8

Total Hydrocarbon Analyzer Operational Theory

located in line with the sample port. See Figure 1-1 for a flow schematic
for instruments equipped with AutoCal valves and Figure 1-2 for
instruments without the AutoCal option.

2.2.4 Flame Ionization Detection Cell

The sample and fuel are combined within a tee fitting located in the
isothermal chamber. The mixed gas is emitted from a burner within the
sensor assembly. Blanket air is introduced into the sensor (or cell) by
means of a separate fitting that is located in the base section of the
assembly. The upper half of the assembly houses the anode-igniter,
collector, and flame guard thermistor. The cell is located at the left hand
front area inside the enclosure for easy access. See Figure 2.1.

2.3 Detection Cell

The upper section of the stainless steel flame ionization cell houses
the cylindrical collector electrode, the high voltage (+260 VDC) anode­igniter coil, and the sensing thermistor of the flame guard circuit (see
cell cross-section Figure 1-3).

WARNING: DANGEROUS HIGH VOLTAGE EXISTS AT THE

ANODE IGNITER COIL (+260 VDC). DO NOT
ATTEMPT TO DISCONNECT THE IGNITER COIL
CABLE OR DISASSEMBLE ANY OF THE FLAME
IONIZATION CELL COMPONENTS WITHOUT
TURNING OFF THE POWER AND DISCONNECTING
THE POWER CORD.

The collector is interconnected with the electrometer-amplifier PC
board by a coaxial cable. Although the cable and fittings are intended for
coaxial service, the cable is actually being used as a shielded single­conductor connection.

The anode-igniter, as its name implies, serves two functions. When
relay K2 at PCB part number B74671 is energized, the coil becomes an
electrical heating element that glows red-hot and ignites the hydrogen
fuel. When relay K2 at B74671 is de-energized, the coil is connected to
the +260 volt DC terminal of the anode-flame guard power supply PC
board. In this configuration, the necessary potential difference is
established between the coil (anode) and collector to promote ionization
of the burned hydrocarbons. The coil functions as the high voltage anode
in all three range positions of the selector switch.

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Operational Theory Model 4020

The thermistor acts as the sensor in the flame guard circuit. Its
ambient temperature resistance is in the 100 K ohms region. When the
flame is ignited, its resistance is reduced by a factor of 100. The
thermistor is coupled to a semiconductor control circuit on the anode­flame guard power supply PC board, which will be described in a
following section.

The cell electrodes of both the anode-igniter and flame guard
thermistor are connected to the electronics chassis by means of a plug-in
cable.

The electrode section of the cell may be removed for inspection by
turning off the power, disconnecting the electrode lead plug, and
removing the screws which retain the electrode assembly in the sensor
body.

Figure 2-1: View Inside Cabinet

2.3.1 Electrometer-Amplifier

The collector cable is coupled directly to a coaxial fitting located on
the electrometer-amplifier PC board. The PC board is located on the side
panel next to but outside of the isothermal chamber. See Figure 2-1. and
consists of an electrometer amplifier and an operational amplifier. This
circuit is a very high-gain, current-to-voltage converter circuit, having

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Total Hydrocarbon Analyzer Operational Theory

an input impedance measuring in the billions of ohms. It is static
sensitive and highly susceptible to contamination. Special care must be
taken in handling this PC board.

Refer to Section 5.5.4: Electrometer-Amplifier PC Board for more
information concerning the electrometer-amplifier and the other printed
circuits that follow.

2.3.2 Anode Power Supply

The high voltage anode power supply components are mounted on
the anode power supply printed circuit board. High voltage regulation is
achieved through the use of series-connected zener diodes. The
simplicity of this circuit’s design can be attributed to the extremely low
current demand of the anode circuit. The positive output voltage is
nominally 125 volts. Output tolerance is ±10 volts from the specified
125 volts.

2.3.3 Flame Guard Circuit

A thermistor-controlled, transistorized switching circuit is employed
to operate a relay in the event of a flame-out condition. A panel indicator
light and fuel shut-off solenoid valve are operated by the relay to alarm
personnel that a flame-out condition has occurred. The fuel shut-off
solenoid valve stops the hydrogen flow.

2.3.4 Flame Ignition Circuit

The flame ignition circuit includes the anode-igniter electrode (in the
detector cell), a transformer, and processor controlled relay. The circuit
is automatically energized after the warm up count down timer expires.

If automatic ignition fails, there will be a message that reports this,
and the flame can be manually ignited by pressing simultaneously the
Up and Down key.

2.3.5 Proportional Temperature Control Circuit

The temperature of the isothermal chamber containing the sampling
components is regulated by a thermistor-directed electronic circuit. The
thermistor and heating element are located in the chamber, and the
balance of the circuit components are mounted on the temperature
controller printed circuit board. A temperature limit switch protects the

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isothermal chamber against excessive temperature, which may occur if
the temperature controlling system fails.

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Total Hydrocarbon Analyzer Installation

Installation

Installation of the Model 4020 Total Hydrocarbon Analyzer
includes:

1. Unpacking

2. Mounting

3. Gas connections

4. Electrical connections

5. Testing the system.

3.1 Unpacking the Analyzer

Although 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 or
shortages to the shipping agent.

3.2 Mounting the Analyzer

The Model 4020 is a general-purpose analyzer and as such is
designed with (non-sealed) enclosures. It must be installed in an area
where the ambient temperature is not permitted to drop below 32ºF nor
rise above 100ºF. In areas outside these temperatures, auxiliary
heating/cooling must be supplied. The 4020 enclosure is oil and dust
resistant and although it is designed to resist moisture, it should NOT be
considered completely watertight. 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 panel must be allowed to be pulled out for possible service
access to all components of the enclosure. Refer to the system/analyzer
outline drawings for dimensions.

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Installation Model 4020

Note: To completely slide the analyzer out of the enclosure, pull
analyzer out until it stops, then push down on the release levers found
almost at the end of the sliders, both sides at the same time.

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 is
possible.

All pertinent dimensions, connecting points, and piping details can
be found in the drawings section as part of the outline, input-output, and
piping diagrams. These drawings are specific to the instrument or
system to which the manual applies.

3.3 User Connections

All user connections are made on the rear panel. Consult the input­output and outline diagrams in the drawing section of the manual. Not
all the features displayed may be present in your system. Refer to any
Addenda for additional information that may apply to your instrument.

3.3.1 Electrical Power Connections

The standard analyzer requires a supply of 100-125VAC, single­phase power. Power connections are made at the rear panel of the unit.
Refer to the input-output diagram for more information. The electrical
power service must include a high-quality ground wire. A high-quality
ground wire is a wire that has zero potential difference when measured
to the power line neutral. If you have the 220 VAC option, you will
require 220 or 240 VAC, 50/60 Hz power. Check the analyzer input­output diagram, power schematic, outline, and wiring diagrams for
incoming power specifications and connecting points.

CAUTION: PRIMARY POWER TO THE SYSTEM SHOULD NOT

BE SUPPLIED UNTIL ALL CUSTOMER WIRING IS
INSPECTED PROPERLY BY START-UP PERSONNEL.

3.3.2 Gas Connections

The analyzer gas connection diagram identifies the various gas
connection points as to function and location. Figure 3-1 shows the gas
connection points for instruments with the optional AutoCal module.

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Total Hydrocarbon Analyzer Installation

Figure 3-1: Gas Connections

Gas connections to the instrument are made at the 1/8”or 1/4”
stainless steel tube fittings provided on the rear panel. Note that the
Purge and Sensor Vent fittings are 1/4” while all other gas connections
are 1/8”.

It is recommended that all gas tubing leading to the connections on
the back of the analyzer be of the coiled type. This will facilitate sliding
the unit out of the case without disconnecting the gas supply to the
analyzer.

Before tubing is connected to the system, it must be decontaminated
to rid it of hydrocarbon deposits. Using a small torch, heat each length
of tubing, while passing nitrogen through it, until it glows red. Begin at
the nitrogen source end and proceed down the length of the tube,
“chasing” the red glow (and hydrocarbon deposits) down to the open
end of the tube. Cap tubing while not in use with suitable non­contaminating caps.

All sample, calibration, and supporting gas lines which deliver gas to
the analyzer must be decontaminated before connection; vent lines do not.

When connecting the various gas lines to the system, be absolutely
certain that no “dead ends” are left; that is, no unused branch lines
should be left capped off, where pockets might form of material that is
not representative of the current contents of the line, or which might
keep contaminants from being purged out of the system.

Note: If different background gases are being used, the user

must supply the necessary valves and any associated
switching equipment for delivering the correct
sample/background gas combination to the analyzer.

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Installation Model 4020

3.3.2.1 VENT CONNECTIONS

Two separate vent connections may be required on your instrument:

 Sensor Vent
 Bypass Vent

Sensor vent and sample bypass vent must run separately.

The sample and bypass vent lines should not be tied together outside
of the system enclosure and the lines need to be installed at a downward
sloping angle to prevent a potential build-up of condensing water vapor
in the vent lines. Follow the installation guidelines below.

Sensor Vent:

All the gases introduced into the detection cell are vented from a
single fitting labeled SENSOR VENT at the rear of the analyzer.

1. TAI recommends that the cell be permitted to vent directly to

atmosphere wherever possible.

2. If the vent line is required, the installation must include a

drop-out pot to collect any water that is formed by the
burning of the hydrogen fuel.

3. The vent line must be constructed so that the water and dirt

cannot collect in it.

4. Sensor vent line must slope downward so condensed water

will freely drain.

SAMPLE BYPASS VENT:

The sample bypassed by the back-pressure regulation system vents
from a separate port labeled

BYPASS VENT at the rear of the analyzer.

If this vent is required, it must be installed so that water and dirt
cannot accumulate in it.

3.3.3 Electrical Connections

Figure 3-1 shows the Model 4020 rear panel. There are connections
for power, digital communications, and both digital and analog
concentration output.

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Total Hydrocarbon Analyzer Installation

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

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 SIELDING.

3.3.3.1 PRIMARY INPUT POWER

The power cord receptacle and fuse block are located in the same
assembly. Insert the power cord into the power cord receptacle.

CAUTION: POWER IS APPLIED TO THE INSTRUMENT'S

CIRCUITRY AS LONG AS THE INSTRUMENT IS
CONNECTED TO THE POWER SOURCE.

The standard power supply requires 110 VAC, 50/60 Hz or 220
VAC, 50/60 Hz (optional) power.

3.3.3.2 FUSE INSTALLATION

The fuse block, at the right of the power cord receptacle, accepts US
or European size fuses. A jumper replaces the fuse in whichever fuse
receptacle is not used.

3.3.3.3

50-PIN EQUIPMENT INTERFACE CONNECTOR

Figure 3-2 shows the pin layout of the Equipment Interface
connector. The arrangement is shown as seen when the viewer faces the
rear panel of the analyzer. The pin numbers for each input/output
function are given where each function is described in the paragraphs
below.

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Installation Model 4020

Figure 3-2: Equipment Interface Connector Pin Arrangement

3.3.3.4 ANALOG OUTPUT

There are four DC output signal pins—two pins per output. For
polarity, see Table 3-1. The outputs are:

0–1 VDC % 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 VDC Range ID: 0.20 V = Low Range

0.5 V = Medium Range

0.80 V = High Range

4–20 mA DC % Range: Current increases 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: 6.8 mA = Range 1

12.0 mA = Range 2

16.8 mA = Range 3

Table 3-1: Analog Output Connections

Pin Function

3 + Range ID, 4-20 mA, floating

4 – Range ID, 4-20 mA, floating

5 + % Range, 4-20 mA, floating

6 – % Range, 4-20 mA, floating

8 + Range ID, 0-1 VDC

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Total Hydrocarbon Analyzer Installation

23 – Range ID, 0-1 VDC, negative ground

24 + % Range, 0-1 VDC

7 – % Range, 0-1 VDC, negative ground

Examples:

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 as 0-10 ppm CH

, then the output would be as shown in

4

Table 3-2.

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 3-3 gives the
range ID output for each analysis range.

Table 3-2: Analog Concentration Output—Example

ppm Voltage Signal Current Signal
CH4 Output (VDC) Output (mA DC)

0 0.0 4.0
1 0.1 5.6
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

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Installation Model 4020

Table 3-3: Analog Range ID Output—Example

Range Voltage Signal Current Signal Application
Output (VDC) Output (mA DC)

Range 1 0.20 6.8 0–1 ppm CH
Range 2 0.50 12 0–10 ppm CH
Range 3 0.80 16.8 0–100 ppm CH

4

4

4

3.3.3.5 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 Table 3-4. They are
capable of switching up to 3 amperes at 250 VAC into a resistive load.
The connectors are:

Threshold Alarm 1:

 Can be configured as high (actuates when

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

 Can be Configured as failsafe or non-failsafe
 Can be configured out (defeated).

Threshold Alarm 2:

 Can be configured as high (actuates when

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

 Configured as failsafe or non-failsafe
 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.

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Total Hydrocarbon Analyzer Installation

(Reset by pressing the STANDBY button to remove
power. Then press STANDBY again and any other
button except SYSTEM to resume

Further detail can be found in Chapter 4, Section 4.5.15.

Table 3-4: Alarm Relay Contact Pins

Pin Contact

45 Threshold Alarm 1, normally closed contact

28 Threshold Alarm 1, moving contact

46 Threshold Alarm 1, normally open contact

42 Threshold Alarm 2, normally closed contact

44 Threshold Alarm 2, moving contact

43 Threshold Alarm 2, normally open contact

36 System Alarm, normally closed contact

20 System Alarm, moving contact

37 System Alarm, normally open contact

3.3.3.6

DIGITAL REMOTE CAL INPUTS

The digital remote calibration input accepts 0 V (off) or 24 VDC
(on) for remote control of calibration. (See Remote Calibration
Protocol below.) See Table 3-5 for pin connections.

The remote cal inputs are shared by the digital range selection mode.
When the user selects the digital range selection mode, the input is used
by the analyzer for range selection. See Section 4.6.13.3 Digital Mode.

Zero: Floating input. A 5–24 V input across the + and –

pins puts the analyzer into the Zero mode. Either side
may be grounded at the source of the signal. A 0–1
volt across the terminals allows Zero mode to
terminate when done. A synchronous signal must
open and close the external zero valve appropriately.

Span: Floating input. A 5–24 V input across the + and –

pins puts the analyzer into the Span mode. Either
side may be grounded at the source of the signal. A

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Installation Model 4020

0–1 volt across the terminals allows Span mode to
terminate when done. A synchronous signal must
open and close external span valve appropriately.

Cal Contact: This relay contact is closed while analyzer is spanning
and/or zeroing. (See Remote Calibration Protocol below.)

Table 3-5: 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 4020 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 quickly close.)

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 quickly close.)

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

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Total Hydrocarbon Analyzer Installation

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

Note: The remote valve connections (described below) provides

signals to ensure that the zero and span gas valves will be
controlled synchronously.

3.3.3.7

RANGE ID RELAYS

There are three dedicated Range ID relay contacts. They are
assigned to relays in ascending order—Low range is assigned to Range
1 ID, Medium range is assigned to Range 2 ID, and High range is
assigned to Range 3 ID. Table 3-6 lists the pin connections.

Table 3-6: Range ID Relay Connections

Pin Function

21 Range 1 ID Contact
38 Range 1 ID Contact
22 Range 2 ID Contact
39 Range 2 ID Contact
19 Range 3 ID Contact
18 Range 3 ID Contact
34 Not Used
35 Not Used

3.3.3.8

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. Pins 13 (+) and 29 (–).

3.3.3.9

PIN OUT TABLE

The following table summarizes all the outputs/inputs available in
the 50 pin D-Sub connector on the backpanel of the analyzer.

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Installation Model 4020

Table 3-7: Pin out of 50 pin D-Sub Connector

pin # Description

1
2
3 + Range ID 4-20 ma
4 - Range ID 4-20 ma
5 + Output 4-20 ma
6 - Output 4-20 ma
7 - Output 0-1 v
8 + Range ID 0-1 v

9 Remote Zero +
10 Remote Span +
11 Remote Zero ­12 Remote Span ­13 Network +
14 Remote Thermistor
15 Zero Solenoid Return
16 Span Solenoid Return
17 Span Solenoid Hot
18 Range 3 Contact
19 Range 3 Contact
20 Alarm 3 C Contact
21 Range 1 Contact
22 Range 2 Contact
23 - Range ID 0-1 v
24 + Output 0-1 v
25
26
27
28 Alarm 1 C Contact
29 Network ­30 Remote Sensor +
31 Remote Thermistor
32 Exhaust Solenoid Hot
33 Sample Solenoid Hot
34 Range 4 Contact/ not used
35 Range 4 Contact/not used
36 Alarm 3 NC Contact
37 Alarm 3 NO Contact
38 Range 1 Contact
39 Range 2 Contact
40 Calibration Contact

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Total Hydrocarbon Analyzer Installation

pin # Description

41 Calibration Contact
42 Alarm 2 NC Contact
43 Alarm 2 NO Contact
44 Alarm 2 C Contact
45 Alarm 1 NC Contact
46 Alarm 1 NO Contact
47 Remote Sensor ­48 Exhaust Solenoid Return
49 Zero Solenoid Hot
50 Sample Solenoid Return

3.3.4 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:

1. The concentration in ppm

2. The range in use (R-1 = Range 1, R-2 = Range 2, R-3 =

Range 3, R-4 = Range 4)

3. The span of the range (0- 10.00 ppm, etc)

4. Mode the analyzer is in: ANLZ, ZERO, or SPAN

5. Which alarms—if any—are tripped (AL–1 and/or AL-2).

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

5.88 ppm R-1 (0- 10.00 ppm) ANLZ AL-1 <CR>

Input: The input functions using RS-232 that have been implemented
to date are described in Table 3-8.

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Installation Model 4020

Table 3-8: Commands via RS-232 Input

Command Description
as<enter> Immediately starts an autospan.
az<enter> Immediately starts an autozero.

Implementation: The RS-232 protocol allows some flexibility in its
implementation. Table 3-8 lists certain RS-232 values that are required
by the Model 4020 implementation.

Table 3-9: Required RS-232 Options

Parameter Setting

Baud 2400
Byte 8 bits
Parity none
Stop Bits 1
Message Interval 2 seconds

3.3.5 Supporting Gases

Normally, four supporting gases of different composition (see
Section 4.1: Equipment) will be required to operate the analyzer. The
recommended composition of these gases is specified in the Application
Data section of the Appendix. The gases should be supplied from
cylinders that are equipped with the type of regulator specified in the
aforementioned sections.

CAUTION: UNDER NO CIRCUMSTANCES SHOULD YOU

EMPLOY A REGULATOR THAT IS NOT EQUIPPED
WITH A METALLIC DIAPHRAGM ANYWHERE IN THE
SYSTEM.

The regulators should be inspected prior to installation to be sure
that they are oil-free. Failure to comply with these directives will result
in a constant drift in analyzer output, as organic compounds will outgas
into the plumbing system at a rate that is related to the ambient
temperature. Use 316 stainless steel, dual-stage regulators only in fuel,
sample, and blanket air lines; shutoff valves should be used downstream
from each regulator.

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Total Hydrocarbon Analyzer Installation

Place the supply cylinders as close to the analyzer as possible, and
interconnect them to the analyzer with new tubing. Be sure that all
plumbing connections are free of leaks.

Note: Use only stainless steel tubing throughout the system.

Consult the assembly, piping, outline drawings, and any
Addenda included with this manual to determine if special
conditions apply.

3.3.5.1 SAMPLE GAS

An oil-free, metallic diaphragm regulator must be installed as close
to the sample point as possible. Use new tubing in the installation. The
output pressure of the regulator should be 30 psig, whenever possible, to
match the settings of other regulators on the support gas tanks; sample
inlet pressure must exceed the operating sample pressure by at least 10
psig and provide at least 1 SCFH bypass flow. In any case, the zero and
span gas regulators should be set to match the sample pressure
regulator—as the back-pressure regulator within the analyzer ultimately
determines the sample flow to the detection cell. Refer to Chapter 4:
Sampling.

3.3.5.2

EFFLUENT

All the gases introduced into the detection cell vent from one fitting
at the rear of the analyzer. TAI recommends that the cell be permitted to
vent directly to the atmosphere wherever possible.

If a vent line is required, the installation must include a drop-out pot
to collect the water that is formed by the burning of the hydrogen fuel.
The vent line must be constructed so that water and dirt cannot collect in
it.

3.3.5.3 SAMPLE BYPASS VENT

The sample bypassed by the back-pressure regulation system vents
from a separate port at the rear of the analyzer. If a vent line is required,
it must be installed so that water and dirt cannot accumulate in it.

3.3.5.4 FUEL AND AIR CONNECTIONS

The fuel used to provide combustion should be a gas mixture
comprised of 40% H2 and 60% N2. The fuel is mixed with air to provide
a combustion source for the analyzer. Connect the fuel and air sources to

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Installation Model 4020

the instrument according to the gas connection diagram included at the
back of this manual.

Note: For applications where the sample gas is hydrogen, the

sample gas doubles as the fuel for combustion and is
diluted with nitrogen. Connect a nitrogen source (40 psig)
to the fuel inlet port. See Figure 3-1.

Note: A gas mixture of 40% H2 and 60% He can be used as fuel
as well.

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Total Hydrocarbon Analyzer Operation

Operation

This section of the manual describes how to setup and operate the
Model 4020 Analyzer. Sections 4.1 through 4.5 describe preliminary
steps and equipment needed to operate the analyzer. Beginning with
Section 4.6, the actual operation of the analyzer is described along with
descriptions of the display prompts, messages and options available to
the user within a menu or sub menu.

4.1 Equipment

The following supporting gases and hardware will be required to
operate the (standard) analyzer:

1. Fuel: A cylinder containing a 40% hydrogen, 60% nitrogen

composition will be required to supply the fuel for the flame
ionization burner. The cylinder is to be equipped with an oil-free
metallic diaphragm regulator (dual stage).

Note: When hydrogen is the parent gas in the application, an

auxiliary source of fuel may not be required. See the
Appendix: Specifications for specific recommendations.

2. Blanket Air: A cylinder of water-pumped (low hydrocarbon)

compressed air will be required to maintain the proper
atmosphere within the cell. The cylinder is to be equipped with
an oil-free, dual stage, metallic diaphragm regulator. Less than
1% of the full scale reading (in the selected measurement range)
of hydrocarbon contamination is advisable, if the instrument’s
accuracy is to be realized.

3. Zero Gas: A cylinder of the parent (or background) gas,

containing less than 10% full scale (of the narrowest range)
hydrocarbon impurity, will be required to zero standardize the
analyzer. For example, if 10 PPM is the narrowest range of the
instrument, then the zero gas impurities are to be less than 1
PPM. The cylinder is to be equipped with an oil-free, dual stage,
metallic diaphragm regulator.

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Operation Model 4020

4. Span Gas: A cylinder containing a composition consisting of the

parent gas and a specified (see Appendix: Specifications) amount
of methane will be required to standardize the sensitivity setting
of the analyzer. The cylinder is to be equipped with an oil-free,
dual stage metallic diaphragm regulator.

Note: The analyzer is capable of analyzing a sample in two

different background gases, O

and N2. To use this feature

2

you must calibrate the instrument with each background
gas. Therefore separate zero and span gases will be
required for each background gas.

5. Sample Pressure Regulation: An oil-free, metallic diaphragm

regulator must be installed at the sample point when possible; see
Section 3.3.5.1 Sample Gas.

6. Background Gas Selector: If using different sample

background gases, a suitable manifold for switching the gas to
the analyzer will be required. It can be either manual or
automatically operated valves.

4.2 Preliminary Power-Off Check List

Make the following checks of the installation before proceeding
further into the start-up procedure:

1. Check to see that the sample and supporting gas installation is in

accordance with the specifications called for in the installation
and application sections of the manual (Chapter 3). Be sure that
the supporting gases are of the proper composition and are
connected to the correct fittings at the rear of the analyzer.

2. Check to see that the electrical installation conforms to the

instructions contained in the installation section (Chapter 3) and
on the input-output diagram.

3. Open the door and check to see that the printed circuit boards

and cables are firmly seated in their respective sockets.

4. Confirm that recorder and alarm connections are properly made.

4.3 Placing the System in Operation

1. Turn the power switch to the ON position.

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Total Hydrocarbon Analyzer Operation

2. Allow at least 2 hours warm-up (heat up sensor & sample

system) after making the air adjustment described below. Warm
up time is set by the software at the factory.

DO NOT attempt to ignite the flame during warm up
countdown. Condensation will occur.

4.4 Activating the Support Gases

4.4.1 Air

1. Set the air tank regulator to 30 psig.

2. Adjust the instrument air regulator until the air pressure

gauge reads the recommended air pressure.

After the air is flowing through the sensor and warm-up time has
been completed, activate the following gases:

4.4.2 Sample Gas

Set the sample gas tank regulator to 30 psig (or a pressure which

matches the sample pressure) and adjust the instrument sample

regulator until its (sample) pressure gauge reads the recommended

sample pressure.

4.4.3 Span Gas

1. Feed span gas to the analyzer. This instrument has an automatic

valve selection feature for directing sample or calibration gas to
the analyzer. See Section 4.6.16 for setup and operation of the
valve selection feature..

2. Set the span gas regulator to 30 psig or to match the sample

pressure.

3. Observe that the instrument sample pressure gauge still reads the

recommended sample pressure and that the bypass flowmeter
reads from 0.5 to 1.0 SCFH.

4.4.4 Fuel

1. Open the main valve on the tank and set the fuel tank pressure

regulator to 30 psig (or to match sample pressure).

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Operation Model 4020

2. To avoid pressure shock to the instrument fuel regulator, slowly

open the secondary valve until it is wide open.

Note: adjust fuel settings only when the red LED (flame failure

light) is off.

Figure 4-1: Front Panel View of Regulator and Gages

4.5 Flame Ignition

Observe that after warm up count down timer reaches zero (timer to
preheat the sensor), the amber heater lamp is blinking (indicating that
the temperature controller is maintaining the temperature setpoint) and
the red flame failure lamp is on. See Figure 4-1.

The Model 4020 will automatically attempt a flame ignition
sequence following the warm-up period which has been preset at the
factory. If the ignition process fails, the instrument will attempt to ignite
the flame a second time. If it continues to fail after the fifth attempt, a
flame failure message will appear on the display. If this occurs refer to
Section 5.

4.5.1 Verification of the Flame Guard Circuit

The operation of the flame guard circuit has been checked at the
factory, but should be re-verified during start-up. Use the following
procedure after ignition of the flame has been achieved:

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Total Hydrocarbon Analyzer Operation

1. Turn off the fuel at the supply cylinder.

2. Observe the fuel pressure gauge on the analyzer control panel. The

gauge indication will decay as the fuel in the line is exhausted.
When the gauge reading reaches the vicinity zero, the flame will
be extinguish as the fuel solenoid shuts off the fuel supply. The
analyzer will automatically try to re-ignite. After 5 attempts, it will
display: flame failure, check air, fuel and the flame failure LED
will be on.

3. Open the cylinder supply valve and re-ignite the flame.

4.5.2 Ignition and/or Flame Guard Circuit Failure

If the flame ignition or guard circuits do not operate as described in
the above two sections, set the instrument fuel regulator to the
recommended pressure. If still fails to ignite, proceed as directed in
Chapter 5: Maintenance & Troubleshooting.

4.6 Analyzer Operation

Although the Model 4020 has been programmed for your application
at the factory, it can be further configured at the operator level, or even
(cautiously) reprogrammed. Depending on the specifics of the
application, this might include all or a set of the following procedures:

 Setting system parameters

 Establish a security password, if desired, requiring

operator to log in

 Establish and start an automatic calibration cycle

 Routine operation

 Calibrate the instrument
 Choose autoranging or select a fixed range of analysis
 Set alarm setpoints and modes of alarm operation

(high, low, failsafe, etc.)

 Program/reprogram the analyzer

 Linearize the ranges

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Operation Model 4020

 Special functions setup

 Calibrate analog output

Procedures for accessing and/or changing parameters as well as
analyzer operation are detailed in the sections to follow. In general, the
sequence of menus available on screen follow a logical course for setup
and operation. It is not required, however to follow this sequential path.
The user could, for instance, go directly to set an analysis range and then
program an offset to the current output for matching a range on the
user’s recording device. The only exception to this is when the
instrument is powered up. It will go through a diagnostic self-test
routine and, if programmed to do so, request a password to be entered
before allowing access to any function.

4.6.1 Default Parameters

The versatility of this analyzer usually results in significant changes
being made to parameters over the course of time to better suit a
particular application. Occasionally processes change requiring
alteration to alarms, filter settings etc. At some time, it may be
beneficial to reset the analyzer to the default conditions as it was when
shipped from the factory. Below is a listing of the default parameters
used in configuring your instrument:

Range/Application: Refer to the data sheet on the application

page found in the appendix of this manual

Range: Manual
Alarm Relays: Active, HI, 80 ppm (alarm 1),

90 ppm (alarm 2), non-failsafe

Zero: Auto disabled, every 7 days, at 12 hours
Span: Auto disabled, every 7 days, at 12 hours
Password: TAI

4.6.2 Style Conventions

The following typeface conventions are used when referring to
screen names, key presses and screen readout:

Screens: Arial 12 pt. type in capital letters. Example:

ANALYZE or MAIN screen or menu.

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Total Hydrocarbon Analyzer Operation

Key presses: <key> The particular keystroke to enter is

placed between < and >. Example:
<enter> or <escape> or <▲> (UP key) or
<▼> (DOWN key.

Only when the keystroke is to be entered

will it be placed between the brackets. If
discussing a particular key it will be typed
as text using all caps. Example: this is the
ENTER key.

Screen Modes: Times New Roman 12 pt. italic. Example:

Analysis Mode or Setup Mode.

Screen Readout: Arial Narrow, 12 pt bold. Example:

AUTOCAL or Zero in 12 days.

4.6.3 Using the Controls

To get the proper response from these controls, press the desired key
(<Escape> or <Enter> or <▲▼>. To enter the screen menu, press any
key.

The item that is adjacent to the arrow on the screen as shown in Figure
4-2,

is the item that is currently selectable by pressing the <Enter> key.

Figure 4-2: Typical VFD Screen Layout

In these instructions, to <Enter> means to press the ENTER KEY,
and to <Escape> means to press the ESCAPE KEY. To scroll <▲> (or
scroll <▼>) means to press UP or DOWN keys as many times as
necessary to reach the required menu item.

4.6.4 Mode/Function Selection

When the analyzer is first powered up, a warm-up for a period
ranging from 1 to 16 hours will occur depending on the exact factory
configuration.

Note: The warm-up period may be bypassed by pressing

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Operation Model 4020

<Enter> at the initialization screen.

The warm-up period is a crucial factor affecting the overall accuracy
for this instrument and should not be bypassed .unless the instrument
has only been off for a short period or for maintenance purposes. Check
Specific Model Information on page iii of this manual as well as any
accompanying Addenda for the specific warm up time required for your
configuration.

After warm-up, the instrument will undergo an initialization and self
diagnostic routine. Once this has been completed, the ANALYZE screen
(Analysis Mode) will appear. The ANALYZE screen is the only screen
of the Analysis Mode. It is also the default screen appearing whenever
the instrument is on and not in the warm-up phase, self testing routines
or purposely put into another mode of operation such as Setup Mode .
The analyzer will automatically return to the ANALYZE screen from
any other input screen whenever the instrument is idle with no buttons
pressed for approximately 20 seconds.

The MAIN MENU screen is the top level in a series of screens used
in the Setup Mode to configure the analyzer for the specific application.
The DOWN/ UP commands scroll through the options displayed on the
VFD screen. The selectable option appears between arrows. When you
reach the desired option by scrolling, <Enter> the selection as described
below.

ESCAPE takes you back up the hierarchy of screens until you reach
the Analyze Mode. ESCAPING any further just toggles between the
MAIN MENU and the ANALYZE screen.

Note: The m ai n m enu or any sub m enu will time out after

approximately 20 seconds, and return to the analyze
screen.

4.6.4.1

ANALYSIS MODE

This is the normal operating mode. The analyzer monitors the
concentration of the sample, displays the percent of the concentration in
the sample stream, and warns of any alarm conditions. Pressing any key
switches you into Setup Mode and brings up its main menu. Setup Mode
switches back to Analyze Mode if no controls are used for more than
twenty seconds.

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Total Hydrocarbon Analyzer Operation

4.6.4.2 SETUP MODE

The MAIN MENU consists of functions you can use to customize
and check the operation of the analyzer. Figure 4-3 shows the functions
available in the Model 4020. They are listed here with brief descriptions:

 AUTO-CAL: (Option) Used to define and/or start an

automatic calibration sequence.

 PSWD: Used to establish password protection or change the

existing password.

 LOGOUT: Logging out prevents unauthorized tampering with

the analyzer settings.

 MODEL: Displays Manufacturer, Model, and Software

version of the instrument.

 SELF-TEST: The instrument performs a self-diagnostic

routine to check the integrity of the power supply, output
boards, cell and amplifiers.

 SPAN: Set up and/or start a span calibration.
 ZERO: start a zero calibration.
 ALARMS: Used to set the alarm setpoints and determine

whether each alarm will be active or defeated, HI or LO
active, and failsafe or not.

 RANGE: Used to set up three analysis ranges that can be

switched automatically with auto-ranging or used as
individual fixed ranges. A digital range selection mode is
incorporated that uses the remote calibration inputs for range
selection.

 FILTER: This function sets the digital filter from 0 to 7, 0

being the fastest response time, and 7 being the slowest. The
default is 4.

 ANALOG-OUT ADJUST: Calibrate Analog Output
 LINEARIZATION: A restricted function not generally

accessed by the end user. It is used to linearize the output for
the range of interest.

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Operation Model 4020

 BACKGROUND GAS: Allows the user to choose between

nitrogen or oxygen as the background gas.

Note: Each background gas has its own zero settings. The first

time you switch from one background gas to the other, the
instrument must be zero calibrated on that gas.

 VALVE SELECTIONS: Allows the user to switch between

sample and calibration gases from an input screen or
automatically depending on the instrument’s mode of
operation. Valve selection can also be disabled.

 STANDBY: Removes power to outputs and displays, but

maintains power to internal circuitry.

Any function can be selected at anytime. Just scroll through the
MAIN MENU with the DOWN/UP keys to the appropriate function, and
ENTER it. The analyzer will immediately start that function, unless
password restrictions have been assigned. (Password assignment is
explained in Section 4.6.7).

4.6.5 Data Entry

4.6.5.1

ENTER

The ENTER key is used in several context-sensitive ways.

1. When the selected option is a function on the MAIN MENU

screen, the function name appears with an arrow next to it.
The ENTER key is used to activate the function. The next
screen for that function or sub function will appear on the
VFD.

2. If the selected option is a modifiable item, the UP or DOWN

keys are used to increment or decrement the item to the value or
action you want. The ENTER key is then used to accept the
value and move you to the next field to continue programming.

3. When the last field is entered, ENTER takes you to the next

screen in the process, or if the process is completed, ENTER
takes you back to the ANALYZE screen.

4.6.5.2 ESCAPE

Pressing the ESCAPE key takes you back to the previous screen.

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Total Hydrocarbon Analyzer Operation

If you do not wish to continue a function, you can abort the session
by escaping. Escaping a function takes the analyzer back to the previous
screen, or to the ANALYZE Function, depending on the nesting level of
screens in the function you are moving out of.

Figure 4-3: Setup Mode Functions

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Operation Model 4020

4.6.6 Setting up an AUTO-CAL

If the analyzer is equipped with the optional auto-calibration feature
(see Chapter 3, Installation), the analyzer can cycle itself through a
sequence of steps that automatically zero and span the instrument (auto
calibration or autocal).

Note: Before setting up an AUTOCAL, be sure you understand

the Zero and Span functions as described in Section

4.6.14, and follow the precautions given there.

Note: If you require highly accurate AUTOCAL timing, use

external AUTOCAL control where possible. The internal
clock in the Model 4020 is accurate to 2-3 %. Accordingly,
internally scheduled calibrations can vary 2-3 % per day.

Note: By default, AUTOCAL is off.

To setup an AUTOCAL cycle for a zero or span event to occur in a
certain number of days:

<any key> Press any key to enter the Setup Mode. The VFD will

display the first 2 lines of functions available.

<▲▼> If the arrow is not adjacent to the AUTOCAL menu item,

use the ▲▼ keys to move the arrow to the proper
position.

<Enter> Press <Enter> to activate the function and move you to

the next screen.

This screen allows you to either enable or disable the AUTOZERO
or AUTOSPAN functions independently. To set up an autocal event,
the appropriate AUTOCAL function (AUTOZERO and/or AUTOSPAN
must be enabled.

<▲▼> If the screen indicates the specific AUTOCAL function is

disabled, press <Enter>, then use the <▲▼> keys to
toggle the enable/disable feature.

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Total Hydrocarbon Analyzer Operation

<Enter> Press <Enter> again to move to the next screen. As an

example, in the case of an AUTOZERO, the arrow
should now point to the line of text: Zero in 7 days as
shown below.

If you are setting a span calibration event press the <▼>

key twice more and enable the AUTOSPAN function.
Then press the <▼> key once more to bring the arrow to
point to the line of text: Span in 7 days.

With the arrow adjacent to the text: Zero in 7 days, (or
Span in 7 days)y if you want to change the day count,
highlight the number by pressing <Enter>.

<▲▼> With the number highlighted, use the <▲▼> keys until

the proper day count value is on screen.

<Enter> Press <Enter>. This accepts the value and moves the

arrow to the next screen line.

Note: You can always press <Escape> to move to the previous

screen line. Repeated Escaping will bring you back to the
MAIN MENU. Pressing <Escape> at the MAIN MENU will
place the instrument in Analysis Mode.

To have a zero (or span) event occur in an hourly time frame is
similar to the above procedures except that you must scroll from the
MAIN MENU using the <▼> key until the appropriate line is reached.
Figure 4-4 shows the set of screens used in the AUTOCAL function.

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Operation Model 4020

Figure 4-4: AUTOCAL Screens

4.6.7 Password Protection

Before a unique password is assigned, the system assigns TAI by
default. This password will be displayed automatically. The operator just
presses <Enter> to be allowed total access to the instrument's features.

If a new password is assigned, then all system parameters can be set
after the password is correctly entered. When logged out, only the
MODEL function, an information only screen, is available.

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Total Hydrocarbon Analyzer Operation

Note however, that the instrument can still be used for analysis or for
initiating a self-test without entering the password. To defeat security
the password must be changed back to TAI.

Note: If you use password security, it is advisable to keep a copy

of the password in a separate, safe location.

To log in, enter the correct password as described in the next section. To
logout, use the LOGOUT function as described in Section 4.6.8.

4.6.7.1 ENTERING THE PASSWORD

To install a new password or change a previously installed password,
you must key in and ENTER the old password first. If the default
password is in effect, pressing <Enter> will enter the default TAI
password for you.

To enter a password:
<any key> Enter MAIN MENU setup by pressing any key.
<▲▼> Use the UP or DOWN key to scroll to PSWD.

<Enter> Press <Enter> to activate the password function. Either

the default TAI password or AAA place holders for an
existing password will appear on screen depending on
whether or not a password has been previously installed.

<Enter> The screen prompts you to enter the current password. If

you are not using password protection, press <Enter> to
accept TAI as the default password.

—or—
<Enter> If a password has been previously installed, enter the

password press <Enter> to scroll through the letters.

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Operation Model 4020

<▲▼> Use the ▲▼ keys to change the letters to the proper

password.

<Enter> The last <Enter> enters the password.

In a few seconds, you will be given the opportunity to change this
password or keep it and go on.

<Enter or Escape> Press <Escape> to move on, or <Enter> to change

the password.

4.6.7.2 INSTALLING OR CHANGING THE PASSWORD

If you want to install a password, or change an existing password,
proceed as above in Entering the Password. When you are given the
opportunity to change the password press <Enter>.

If you elected to change the password, the password assignment
screen appears.

<Enter> Use <Enter> to move to the character(s) you want to

change.

<▲▼> Use the UP and DOWN keys to cycle between the

available characters from the embedded character set.

<Enter> Press <Enter> to accept the character.
<Enter> Press <Enter> to bring up the password verification

screen.

Use the same process of <Enter> to select the character

position followed by <▲▼> to type in the characters of
the password. The last <Enter> will verify your password
and store it in the microprocessor.

You will now be automatically returned to the Analyze Mode.

Note: If you log off the system using the LOGOUT function in the

MAIN MENU, you will now be required to reenter the

password to gain access to Alarm and Range functions.

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Total Hydrocarbon Analyzer Operation

4.6.8 Logging Out

The LOGOUT function provides a convenient means of leaving the
analyzer in a password protected mode without having to shut the
instrument off. By entering LOGOUT, you effectively log off the
instrument leaving the system protected against use until the password is
reentered.

To log out:
<▲▼> From the MAIN MENU scroll to field of LOGOUT

function.

<Enter> Press <Enter> to logout

The screen will display the message:

Pressing <Enter> will logout the current user and protect the system
from unauthorized changes to parameters. All users will still have access
to the SELF-TEST function and the instrument will function normally in
Analyze Mode. If you press <Escape>, the current password will still be
in effect and the user has not logged off.

4.6.9 System Self-Diagnostic Test

The Model 4020 has a built-in self-diagnostic testing routine.
Preprogramming signals are sent through the power supply, output
board, preamp board and sensor circuit. The return signal is analyzed,
and at the end of the test the status of each function is displayed on the
screen, either as GOOD or BAD. If any of the functions fail, the System
Alarm is tripped. The following is an example of what is displayed at the
end of the diagnostic routine.

5 Volts Test – GOOD (status of the 5 volt power supply)

15 Volts Test – GOOD (status of the +/-15 volt power supply)

DACA Test – GOOD (status of the % of range analog output)

DACB Test – GOOD (status of the range ID analog output)

Pre-L Test – GOOD (status of the low gain of the amplifier)

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Operation Model 4020

Pre-M Test – GOOD (status of the medium gain of the
amplifier)

Pre-H Test – GOOD (status of the high gain of the amplifier)

Note: The self diagnostics are run automatically by the analyzer

whenever the instrument is turned on, but the test can also
be run by the operator at will.

To initiate a self-test:
<▲▼> From the MAIN MENU scroll to the SELF-TEST

function.

<Enter> Activate the SELF-TEST function by pressing <Enter>.

This brings up the SELF-TEST initialization screen.

<Enter or Escape> Start the diagnostic testing routine by pressing

<Enter> or cancel out by pressing <Escape>.

If you pressed <Enter> the self-test routine will begin and

after a few moments the results will appear onscreen. The
module is functioning properly if it is followed by OK. A
number indicates a problem in a specific area of the
instrument. Refer to Chapters

Troubleshooting

for number-code information.

Maintenance and

To return the analyzer to the MAIN MENU, press
<Enter> after the results screen.

If you pressed <Escape> you will be returned to the
Analyze Mode.

4.6.10 The Model Screen

The MODEL screen displays the manufacturer, model, and software
version information. It is accessed via the MAIN MENU by scrolling
(▲▼> to MODEL and pressing <Enter>.

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Total Hydrocarbon Analyzer Operation

4.6.11 Zero and Span Functions

The ZERO and SPAN functions are used to calibrate the analyzer.
These functions can be performed either manually or automatically (if
equipped with the autocal option). The ZERO and SPAN are separate
functions but operate similarly. Hence, the description that follows
refers to the ZERO function but the same procedure is used for SPAN.

The analyzer is calibrated using zero and span gases as described in
Section 4.1. This section assumes that these gases have been properly
connected and the lines checked for leaks.

Note: You must zero and span calibrate the instrument with each

background gas (O2 or N2) you intend on using.

To initiate a zero (span) calibration, first inform the instrument
which background gas is being used:

<▲▼> From the MAIN MENU, scroll down to the Background

Gas function.

<Enter> Press <Enter> to activate the Background Gas function.
<▲▼> Use the UP or DOWN key to toggle between O2 and N2

until the correct background gas is displayed.

<Enter> Press <Enter> again to inform the instrument which gas

is being used for the background gas.

The parameters for the calibration that follows will be stored in
memory for the background gas selected.

<▲▼> From the MAIN MENU, scroll down to the ZERO

(SPAN) function.

<Enter> Press <Enter> to activate the ZERO (SPAN) function.

The next screen will prompt you to select either manual
or automatic Zero calibration.

Manual Zero (Span)

If you select manual zero (span), the next screen will allow you to
enter the concentration in ppm hydrocarbon (methane equivalent) of
your zero(span) gas.

Note: Make sure that the proper calibration gas is flowing into the

analyzer before initiating this function. Depending on your

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Operation Model 4020

sample system, you may have to flow calibration gas for
several minutes to purge the gas line of sample gas.

<Enter> With the arrow adjacent to Zero (Span) as shown above,

press <Enter> to activate the sub function.

<▲▼> Use the UP/DOWN keys to increment or decrement the

concentration value until the known value of your
zero(span) gas concentration is displayed.

<Enter> Press <Enter> to accept this value.
<▼> Press the DOWN key once to move the arrow down one

line to the text Zero (Span) Begin.

<Enter> Press <Enter> to start the calibration.

The 4020 will begin to analyze the concentration of the zero (span)
calibration gas and LED display above the VFD will change to reflect
the calibration gas concentration as the analysis proceeds. Internally, the
microprocessor calculates the difference between successive samplings
and displays the concentration as it changes. In MANUAL mode, the
operator can terminate the calibration at any point by scrolling to Finish
and pressing <Enter>. Wait until the concentrations as shown on the
screen stabilizes before ending the calibration After terminating the
calibration the zero (span) value will be stored in the microprocessor’s
memory and you can continue with additional calibration or escape to
Analyze Mode.

If you will be using a second background gas, repeat the above
procedures for the second background gas.

Auto Zero

If you selected Auto for the zero calibration, The microprocessor will
determine the appropriate termination point for the zero or span
calibration based on the rate of change of concentration with time as the

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Total Hydrocarbon Analyzer Operation

value approaches the zero (span) concentration you entered for the zero
(span) gas.

To automatically zero (span) the instrument, make sure the proper
background gas is selected as described above, then:

<▲▼> From the MAIN MENU, scroll down to the ZERO

(SPAN) function.

<Enter> Press <Enter> to activate the ZERO (SPAN) function.

The next screen will prompt you to select either manual
or automatic Zero calibration.

<▲▼> Choose Auto zero (span) by toggling between Manual

and Auto using the UP/DOWN keys.

<Enter> Select Auto by pressing <Enter>.

The next screen will allow you to enter the concentration in ppm
hydrocarbon (methane equivalent) of your zero(span) gas.

Note: Make sure that the proper calibration gas is flowing into the

analyzer before initiating this function. Depending on your
sample system, you may have to flow calibration gas for
several minutes to purge the gas line of sample gas.

Also, make sure that the correct background gas is
selected in the Background Gas screen. See Section 4.7.2
Background Gas Selection.

<Enter> With the arrow adjacent to Zero (Span) as shown above,

press <Enter> to activate the sub function.

<▲▼> Use the UP/DOWN keys to increment or decrement the

concentration value until the known value of your
zero(span) gas concentration is displayed.

<Enter> Press <Enter> to accept this value.
<▼> Press the DOWN key once to move the arrow down one

line to the text Zero (Span) Begin.

<Enter> Press <Enter> to start the calibration.

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Operation Model 4020

The calibration process will initiate and after a few moments the
LED digital display will indicate the zero or span gas concentration and
the VFD display will inform the user it has finished the calibration.

<Enter> To accept the calibration, press <Enter>. To reject this

calibration and repeat the process, press <Escape>.

The zero (span) process will automatically conclude when the output
is within the acceptable range for a good zero (span). If accepted by the
operator, the analyzer automatically returns to the Analyze mode.

4.6.12 The Alarms Function

The Model 4020 is equipped with 2 fully adjustable concentration
alarms and a non-adjustable system failure alarm. Each alarm relay has a
set of form "C" contacts rated for 3 amperes resistive load at 250 VAC.
See Figure in Chapter 3, Installation and/or the Interconnection Diagram
included at the back of this manual for relay terminal connections. The
alarm relay contacts are accessible to the user from the 50-pin
Equipment Interface connector.

The system failure alarm has a fixed configuration described in
Chapter 3 Installation.

The concentration alarms can be configured from the ALARM
function screen as either high or low alarms by the operator. The alarm
modes are set at the factory as non-failsafe however they can be defeated
by the operator from within the ALARM function screen. In failsafe
mode, the alarm relay de-energizes in an alarm condition. For
non-failsafe operation, the relay is energized in an alarm condition.

The setpoints for the alarms are also established using this function.

Prior to programming the alarms you should decide how they should
be configured. The choice will depend upon your process. Consider the
following points:

 Which if any of the alarms are to be high alarms and which if

any are to be low alarms?

Setting an alarm as HIGH triggers the alarm when the

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Total Hydrocarbon Analyzer Operation

concentration rises above the setpoint. Setting an alarm as
LOW triggers the alarm when the concentration falls below
the setpoint.

 Are the alarms to be set as:

 Both high (high and high-high) alarms
 One high and one low alarm
 Both low (low and low-low) alarms.

 Are the alarm contacts to be fail safe or non-fail safe?
 Are either of the alarms to be defeated?

The defeat alarm mode is incorporated into the alarm circuit so that
maintenance can be performed under conditions which would normally
activate the alarms.

Note: If you are using password protection, you will need to enter

your password to access the alarm functions. Follow the
instructions in section 4.6.7.1 to enter your password.
Once you have clearance to proceed, you can enter the
ALARM function.

To configure or set the alarms:

Activate or Defeat Alarms

<▲▼> Scroll to the ALARM function using the UP/DOWN

keys.

<Enter> Activate the ALARM function by pressing <Enter>.
This brings you to the next alarm screen which allows

you to activate or defeat alarm 1.

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Operation Model 4020

<Enter> Press <Enter> to move to the Active/Defeat field.
<▲▼> Use the UP/DOWN keys to toggle between Active and

Defeat.

<Enter> Press <Enter> to accept the entry and move the arrow to

the next function (High/Low).

CAUTION: IT IS NOT GOOD PRACTICE TO SILENCE AN

EXISTING ALARM BY SETTING THE ALARM
ATTRIBUTE TO ‘DEFEAT”. THE ALARM WILL NOT
AUTOMATICALLY RETURN TO “ACTIVE” STATUS.
IT MUST BE RESET BY THE OPERATOR. IF IT IS
NOT RESET, YOUR PROCESS WILL BE RUNNING
WITHOUT SAFEGUARDS THIS INSTRUMENT IS
DESIGNED TO PROVIDE.

Setting Alarms as High or Low

If the arrow is not already adjacent to the text High/Low, use the
above procedure to relocate the arrow to this function as shown below.

<Enter> Press <Enter> to move to the High/Low field.
<▲▼> Use the UP/DOWN keys to toggle between High and

Low.

<Enter> Press <Enter> to accept the change and move to the next

alarm function.

Entering or Changing a Setpoint

If the arrow is not already adjacent to the text AL-X XX.XX ppm, use
the above procedure to relocate the arrow to this function as shown
below.

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<Enter> Press <Enter> to move to the setpoint field.
<▲▼> Use the UP/DOWN keys to increase or decrease the

value of the setpoint.

<Enter> Press <Enter> to accept the setpoint value and move to

the next alarm function.

4.6.13 The Range Function

The RANGE function allows you to:

 MANUAL or AUTO: Manually (MANUAL)or automatically

(AUTO) select the concentration range of analysis.

 DGTL: Use the 24 VDC remote zero and remote span inputs

to select the range.

In the MANUAL screen, you are further allowed to define the low
(concentration) limits of each range, and select a single, fixed range to
run.

CAUTION: IF THIS IS A LINEA RIZED APPLICATION, THE NEW

RANGE MUST BE WITHIN THE LIMITS
PROGRAMMED USING THE LINEARIZATION
FUNCTION, IF LINEARIZATION IS TO APPLY
THROUGHOUT THE RANGE. FURTHERMORE, IF
THE LIMITS ARE TOO SMALL A FRACTION OF THE
ORIGINALLY LINEARIZED RANGE (APPROX 10 %
OR LESS), THE LINEARIZATION WILL BE
COMPROMISED.

4.6.13.1 MANUAL (SELECT/DEFINE RANGE) SCREEN

The Manual range-switching mode allows you to select a single,
fixed analysis range. It then allows you to redefine the upper and lower
limits, for the range. To enter a MANUAL or fixed range:

<▲▼> Scroll to the Range function using the UP/DOWN keys.
<Enter> Press <Enter> to activate the RANGE function.

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<Enter> Press <Enter> again to move to the Auto/MAN field.
<▲▼> Use the <▲▼> keys to toggle between Auto and

Manual.

<Enter> Press <Enter> when Man is displayed on screen.

The next screen prompts you to select a range: R1, R2 or
R3.

<Enter> Press <Enter> to highlight the Range field.
<▲▼> Use the UP/DOWN keys to choose R1, R2 or R3.
<Enter> Press <Enter> to accept the displayed range. The arrow

will move to the line for defining that particular range. If
you don’t need to adjust the range setting, <Escape> back
to the Analyze Mode and note that it is using the fixed
range you entered.

If you need to alter the range setting:

<Enter> Use the <Enter> key to move to the value you want to

change to define the range you want to work with.

<▲▼> Use the UP/DOWN keys to cycle the numbers up or

down for each digit.

<Enter> Use the <enter> key to move to the next character

placeholder in the number field.

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<Enter> When the last digit has been entered, press <Enter> again

to accept the value or <Escape> to abort the numerical
entry.

This same procedure is used to select and define all ranges.

4.6.13.2

AUTO RANGE

Rather than defining a specific range to work in, you can set the
instrument for autoranging. In the autoranging mode, the microprocessor
automatically responds to concentration changes by switching ranges for
optimum readout sensitivity. If the upper limit of the operating range is
reached, the instrument automatically shifts to the next higher range. If
the concentration falls to below 90% of full scale of the next lower
range, the instrument switches to the lower range. A corresponding shift
in the DC concentration output, and in the range ID outputs, will be
noticed.

Note: As required by the autoranging software, R1, R2 and R3

must be defined and be linearly increasing, which means
R1<R2<R3.

The autoranging feature can be overridden so that analog output
stays on a fixed range regardless of the contaminant concentration
detected. If the concentration exceeds the upper limit of the range, the
DC output will track until it saturates at 110 % of full scale, in other
words: 1.1 V or 21.6 mA using the current output.

However, the digital readout and the RS-232 output of the
concentration are unaffected by the fixed range. They continue to read
beyond the full-scale setting until amplifier saturation is reached. Below
amplifier saturation, the over range readings are accurate UNLESS the
application uses linearization over the selected range.

To setup automatic ranging:
<▲▼> Scroll to the Range function using the UP/DOWN keys.
<Enter> Press <Enter> to activate the RANGE function.

<Enter> Press <Enter> again to move to the Auto/MAN field.

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<▲▼> Use the <▲▼> keys to toggle between Auto and

Manual.

<Enter> Press <Enter> when Auto is displayed on screen.

This sets the instrument in the Autoranging mode.

<Escape> Use Escape to move back to the Analyze Mode. Note that

the analyzer will now automatically switch analysis
ranges as the concentration rises above or below the
range limits.

4.6.13.3

DIGITAL MODE

The digital mode (DGTL) for range selection uses the remote zero
and span inputs to select the range according to Table 4-1.

Note: The remote calibration feature (remote zero and remote

span) will be inoperable when the instrument is set for
digital range selection. Placing the instrument back into
either manual range selection or autoranging will
reestablish the functioning of the remote calibration
feature.

Table 4-1: Digital Range Selection Signals

Contacts

Zero Span Range

Low Low Autorange mode

Low High R3
High Low R2
High High R1

To use the digtal input range selection:

<▲▼> Scroll to the Range function using the UP/DOWN keys.
<Enter> Press <Enter> to activate the RANGE function.

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<Enter> Press <Enter> again to move to the dgtl field.
<▲▼> Use the <▲▼> keys to toggle between the Auto, Manual

and Digital modes

<Enter> Press <Enter> when Dgtl is displayed on screen.

This sets the instrument in the Digital mode.

<Escape> Use Escape to move back to the Analyze Mode. Note that

the analyzer will now switch analysis ranges according to
the inputs from the remote zero and span ports.

Note: When the instrument is operating in this mode, the remote

zero and span inputs will not trigger a calibration event.

4.6.14 Digital Filter Setup

The Model 4020 analyzer has the option of decreasing or increasing
the amount of filtering on the detector signal. This feature enhances the
basic filtering done by the analog circuits by setting the amount of
digital filtering applied by the microprocessor. The digital filter setup
function is accessed from the MAIN MENU. To set the amount of
digital filtering:

<▲▼> From the MAIN MENU, scroll to the FILTER function

using the UP/DOWN keys.

<Enter> Press <Enter> to activate the FILTER function.

<Enter> Press <Enter> again to move to the Filter index field.
<▲▼> Use the UP/DOWN keys to increment or decrement the

amount of filtering to be applied by the microprocessor.

This index can be adjusted from 0, minimum digital

filtering, to 7, maximum digital filtering. The default

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Operation Model 4020

setting is 4 and that should suffice for most applications.
In some applications where speeding the response time
with some trade off in noise is of value, decrease the
value for the digital filter. In applications where the
signal is noisy, increase the value. Decreasing the digital
filter index will result in a slower response time.

4.6.15 Fuel Display

This screen displays the fuel type this instrument is set up for:
40%H2/60%N2, or 100% H2, or 100%N2. It is an information only
screen and has no bearing on the analyzer performance.

4.6.16 Valve Selections

This 4020 analyzer has the option of 3 input streams. The rear panel
of the analyzer has 3 gas inputs labeled: “SAMPLE", "SPAN" and
"ZERO".

The particular gas stream sent to the analyzer can be determined in
one of three ways:

1. Valve selection disabled. This option has the “SAMPLE”

valve always open, typically to deliver sample gas to the
analyzer.

2. User Select . The user can select which port opens to the

analyzer.

3. By Function: In this option, a specific gas port opens to the

analyzer depending on the current mode of the analyzer. For
instance, when performing a zero calibration, the “ZERO”
port would be open while “SAMPLE” and “SPAN” ports
would be closed.

To enable/disable or select a specific valve selection mode:

<▲▼> From the MAIN MENU, scroll to the VALVE

SELECTIONS function using the UP/DOWN keys.

<Enter> Press <Enter> to bring up the valve selection setup

screen.

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<▲▼> Use the <▲▼> keys to toggle between the Disabled,

User Select and Default (by Function) modes.

<Enter> Press <Enter> when the appropriate function is displayed

on screen.

<Escape> Use Escape to move back to the Analyze Mode. Note that

the analyzer will now switch gas to the analyzer
depending on the choice shown on screen as detailed
below.

4.6.16.1 DISABLED

When the valve selection mode “Disabled” is selected, the gas
connected to the sample port will be fed to the analyzer, i.e. the
“SAMPLE” port will always be open as the default stream fed to the
analyzer. During all modes of operation (Analyze, Span, or Zero), the
valve position will not be indicated on the screen as shown below.

or

and so forth for the zero mode.

4.6.16.2

USER SELECT

This option of valve selection allows the user to determine the
particular gas stream sent to the analyzer. Note that the valve selected
will be open during ALL modes of the instrument operation (Analyze,
Span and Zero).

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Operation Model 4020

There are three choices within the User Select option corresponding
to the valve the user elects to be open to the analyzer (Sample, Span or
Zero). The second line of the display will indicate the current valve
selection.

To select the valve to be opened to the analyzer:
<▲▼> From the VALVE SELECTIONS menu, Use the <▲▼>

keys to toggle the option to USER SELECT

<Enter> Press <Enter> to bring up the USER SELECT screen.

▲▼> Use the <▲▼> keys to toggle between the options of:

“ALWAYS SAMPV” (sample valve)
“ALWAYS SPAN” (span valve)
“ALWAYS ZERO” (zero valve)

<Enter> Press <Enter> when the appropriate valve selection is

displayed on screen.

<Escape> Use Escape to move back to the Analyze Mode. Note that

the analyzer will now switch gas to the analyzer from the
selected port regardless of whether the analyzer is in
analyze or calibration mode.

As an example of the display in Analyze mode when USER SELECT
is the current valve selection mode and “Always SAMPLE” valve is
chosen, the display will be as follows:

or when in SPAN mode:

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4.6.16.3 DEFAULT (BY FUNCTION)

In the default mode of valve selection, the specific valve that is open
to the analyzer depends on whether the analyzer is in Analysis mode or
is in a calibration mode. If it is in Analysis mode, the “SAMPLE” valve
is open to the analyzer. If it is in a calibration mode then either the
“SPAN” or ZERO” valve will be open to the analyzer.

To switch to the default mode of valve operation:
<▲▼> From the VALVE SELECTIONS menu, Use the <▲▼>

keys to toggle the option to default

<Enter> Press <Enter> to bring up the valve selection default

screen.

▲▼> Use the <▲▼> keys to toggle to the “DEFAULT”

option.

<Enter> Press <Enter> when “DEFAULT” is displayed on screen.
<Escape> Use Escape to move back to the Analyze Mode. Note that

the analyzer will now switch either sample or calibration
gas (zero or span) to the analyzer depending on the
function of the analyzer, whether it is analyzing a sample
gas or calibrating.

During analysis, the screen will display as:

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While in span calibration, the screen will display as:

with a similar display for a zero calibration except the zero valve will be
indicated as open (“ZERO ZEROV”).

4.6.16.4 OBSERVING THE GAS STREAM CONCENTRATIONS

The actual gas concentrations of the gas streams can be observed
using two different methods:

1. Use the USER SELECT option of the VALVE

SELECTIONS menu and choose the appropriate valve to
open from the second line of the display. Then return to
Analysis mode by repeatedly pressing <Escape> and observe
the concentration of that stream on the display.

Note: With this technique, the alarms are not suppressed and

depending on the gas and the alarm setpoint, it could
trigger an alarm.

2. Use the DEFAULT option of the VALVE SELECTIONS

menu and select the SPAN (or ZERO) function from the
MAIN MENU. With the SPAN (or ZERO) function
selected, select MANUAL FINISH from the first line of the
display on the SPAN or ZERO submenu. The display will
show:

Or

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Note: The actual displayed concentration may be different

depending on your calibration gas.

Then begin the span or zero routine and observe the
concentration on the screen. Since the analyzer is in a calibration
mode, the alarms will be suppressed.

Note: Make sure you reset the valve selection to the desired

mode after completion of either of these procedures.

4.6.17 Standby

This function allows you to place the instrument in STANDBY.

CAUTION: STANDY SHUTS DOWN POWER TO THE DISPLAYS

ONLY. INTERNAL CIRCUITS ARE STILL ENERGIZED
AND ELECTRICAL SHOCK HAZARD STILL EXISTS.

To place the instrument in STANDBY status:
<▲▼> From the MAIN MENU, scroll to the STANDBY

function using the UP/DOWN keys.

<Enter> Pressing <Enter> places the instrument in STANDBY.
To exit STANDBY, scroll again to the STANDBY

function and press <Enter> again.

4.7 Advanced User Functions

The Model 4020 provides additional functions for tailoring the
instrument to your specific application. These functions include:

 Analog Adjust
 Linearization

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 Background Gas Selection

4.7.1 Zero Offset Adjustment

The software in this instrument provides a way to enter an offset to
the zero of the analyzer. This may be useful if, for example, the zero gas
is not pure and it contains some hydrocarbon. In this case, the reading
will have an offset that will be constant throughout its working range.
Thus, by entering an initial offset to the output (either current or
voltage), the display will match the output over the range of the
application.

Note: This adjustment only affects the % of range output of

Channel 1.

To access the offset function:
<▲▼> From the MAIN MENU, scroll to the ANALOG

ADJUST function using the UP/DOWN keys.

<Enter> Pressing <Enter> activates the function and takes you to

the next screen.

<Enter> Use the <Enter> key to move over to the Offset field.
<▲▼> Use the UP/DOWN keys to change each digits value.
<Enter> Use the <Enter> key to accept a digit and move to the

next character position. The final enter will accept the
value and move the arrow to the function which allows
you to set the gain.

Use the same procedure to set the gain of the instrument. After the
last digit is entered, the final <Enter> press will accept the gain value.

The value you enter for the offset to zero or gain will be
automatically added to the reading. Thus, if you entered -0.10 for zero
offset, the display will show -0.10 for zero concentration.

During calibration, when the instrument enters the zero mode in
AUTO, the instrument will do the work of bringing the reading back to
zero plus the offset value that was entered. If you chose MANual zero

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mode, then you must adjust the zero of the instrument to read zero plus
the value entered as offset.

4.7.2 Background Gas Selection

The 4020 Analyzer can be used to analyze sample gas in a
background of either O

or N2. This menu is used to inform the

2

instrument which background gas is being used. The analyzer will then
apply the proper calibration parameters to the measurement process.

Note: Separate zero and span calibrations must have been

performed prior to using selected sample/background gas
for analysis.

To select a background gas:
<▲▼> From the MAIN MENU, scroll to the BACKGROUND

GAS function using the UP/DOWN keys.

<Enter> Pressing <Enter> activates the function and takes you to

the next screen.

<Enter> Use the <Enter> key to move over to the gas field (O2 or

N2).

<▲▼> Use the UP/DOWN keys to toggle between the two

options..

<Enter> Use the <Enter> key to accept the appropriate

background gas when it is displayed.

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Maintenance & Troubleshooting

WARNING: DANGEROUS HIGH VOLTAGES EXIST INSIDE THIS

INSTRUMENT.
THERE ARE NO USER SERVICEABLE PARTS

WITHIN THE COVER ON THE INSIDE OF THE DOOR,
INSIDE THE ISOTHERMAL CHAMBER, (SAMPLE
SYSTEM), AND ON THE ELECTROMETER­AMPLIFIER PC BOARD. WORK IN THESE AREAS
MUST BE PERFORMED BY AUTHORIZED AND
TRAINED PERSONNEL ONLY.

BEFORE STARTING ANY OF THESE MAINTENANCE
AND TROUBLESHOOTING PROCEDURES, READ THE
CAUTIONS AND WARNINGS INCLUDED IN THE
SECTION TITLED “ADDITIONAL SAFETY WARNINGS”.
PAY SPECIFIC ATTENTION TO THE PROCEDURES
FOR REMOVAL OF INTERNAL INACCESSIBLE SHOCK
HAZARDS. IF THE INSTRUMENT MUST BE TURNED
ON DURING ANY OF THESE MAINTENANCE AND
TROUBLESHOOTING PROCEDURES, BE CAREFUL
AND WORK WITH THE ONE HAND RULE:

Work with one hand only.
Keep the other hand free without

contacting any other object. This reduces
the possibility of a ground path through
the body in case of accidental contact
with hazardous voltages.

CAUTION: MANY OF THE ELECTRICAL PARTS WITHIN THE

MODEL 4020 ARE SUSCEPTIBLE TO DAMAGE
FROM ELECTROSTATIC DISCHARGE (ESD). USE
ESD SAFE PROCEDURES WHEN HANDLING OR
WORKING WITH ELECTRONIC COMPONENTS

.

If the analyzer is suspected of incorrect operation, always evaluate
performance with zero or span gas flowing in the sample path. Never

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attempt to evaluate performance on sample gas. If analyzer sensitivity is
questionable, use the span gas. For all other evaluations, use the zero gas
and low range for maximum sensitivity. The important consideration is
to control as many variables as possible. Using cylinder-supplied gases
of known hydrocarbon content eliminates the possibility of introducing
an unknown variable.

Do not overlook the seemingly obvious. Check to see that power is
available for the instrument (and of the proper voltage, etc.), and that
connections are correct. Also verify that support/calibration gases are
not depleted.

5.1 Measuring Circuit Electrical Checks

If the analyzer performs erratically on zero gas, the trouble can be
related to either the integral gas control systems, or the electronics. To
isolate the problem, the two systems must be separated. To isolate the
electronics, employ the following procedure:

1. Pull analyzer out of the drawer, remove sample system top cover,

remove and disconnect the collector cable from the sensor
leaving it attached to the electrometer board. (Consult schematic
and assembly drawings for circuitry and location). With this
cable disconnected, the electronic circuitry is completely isolated
from the gas control system and cell.

2. Select the auto measurement range (for maximum sensitivity)

and adjust the zero offset value until the readout device indicates
above midscale. (The span control should already be set)

5.1.1 Loss of Zero Control

If the zero cannot be controlled as directed above, a failure has
occurred in either the power supply or the electrometer-amplifier. Use
the following procedure to isolate the fault:

With a digital voltmeter (DVM) set to read 15 VDC, check the
positive and negative 15 V output of the power supply as follows:

(See schematic D65506 drawing of assembly PCB C65507A for
power supply PC board).

1. Connect the voltmeter leads across tantalum capacitor C1. Note

the positive polarity is marked on the PCB silkscreen. The
measured voltage should be 15±1 volt.

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2. Then connect the DVM leads across tantalum capacitor C3. Note

the positive polarity is marked on the PCB. The Plus side
connects to ground. Measured voltage should be -15±1 volt.

If correct readings are not obtained at both points, power supply has
failed, and that printed circuit card must be replaced. If correct readings
are noted, the electrometer-amplifier has failed, and that printed circuit
card must be replaced.

Note: TAI recommends that spares for each of the printed

circuits be kept on hand so that service can be restored
immediately. The faulty circuit card can be returned to the
factory for repair. Unless personnel knowledgeable in
electronics are available, do not tamper with the circuits.

5.1.2 Anode Voltage Check

If the output can be adjusted by the zero control (the above section,
step 2), the cell anode voltage should be verified as follows:

WARNING: THESE PROCEDURES SHOULD BE CARIED OUT

ONLY BY PERSONNEL FAMILIAR WITH HIGH
VOLTAGE CIRCUIT BOARDS. THE ANODE-IGNITER
UNIT AND ASSOCIATE CIRCUITRY INVOLVE
DANGEROUSLY HIGH VOLTAGES.

Refer to the cell wiring diagram. Using a voltmeter set to measure
125 VDC, check the voltage on either of the anode-igniter electrodes, as
follows:

1. Connect the negative voltmeter lead to ground and the positive

lead to either electrode. Be careful not to short the circuit by
touching both an electrode and the cell body simultaneously. The
reading obtained should be 125±10 VDC.

2. If no reading is obtained, disconnect the anode-igniter cable and

check for the voltage on pin “J4-1” of the connector located at
PC board part number B74671. If the proper voltage is still not
present, replace the flame guard and anode power supply PC
board. If it is, check the wiring in the anode-igniter cable plug. If
necessary, the circuit board can be replaced by first turning off
the power, then removing 4 screws holding the board.

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WARNING: DO NOT TOUCH CAPACITOR C1 OR C2 OR THEIR

RELATED CIRCUIT FOILS. A SHOCK HAZARD MAY
EXIST.

Carefully remove the circuit board without touching any connections
which might lead to C1 or C2. After removal, discharge the two
capacitors by placing a jumper wire across each.

3. The anode voltage may also disappear or be greatly diminished

when condensation inside the sensor has occurred, shorting the
igniter to the sensor body across the wet insulator. This usually
occurs when the flame is turned on, if the sensor has not been
preheated for at least 1 hour.

5.1.3 Electronic Stability

If the checks outlined above indicate that conditions are normal,
allow the analyzer to run electronically with the collector cable
disconnected for several hours in the lowest range, and with the zero
offset value adjusted so that the recorder is reading midscale. If all is
normal electronically, a noise-free (pen width) recording, showing
absolutely no instability, should be obtained for as long as the analyzer
is allowed to run in this configuration. If the recording obtained is noisy
or erratic, replace the electrometer-amplifier PC board.

5.1.4 Printed Circuit Board Replacement

If performance is not adequate, then the analyzer must be
recalibrated as described in Section 4.6.14: Calibration before being
placed back in service.

Whenever the flame guard and anode power supply printed circuit
board have been replaced the analyzer must be recalibrated.

If the instrument performs as outlined in this section, the problem is
not related to the measuring circuit electronics.

5.1.5 Collector Cable

Before reconnecting the collector cable, check the continuity of the
center wire of the cable with an ohmmeter by measuring between the
center pins at each plug on the lowest resistance scale of the meter. Flex
the cable while making this measurement to be sure that there is not an

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intermittent open circuit. If there is, replace the cable. Do not attempt to
repair the cable, as special tooling is required to disassemble and
reassemble the cable plugs.

5.2 Temperature Control Electronic Check

If the heating circuit fails, the output of the analyzer will tend to drift
with changes in ambient temperature. Such a failure will be more
evident in the low range. If the temperature environment surrounding the
analyzer is closely regulated, failure in this circuit might go unnoticed
after the initial failure. If the environment follows day and night
temperature changes, the analyzer will show a diurnal, bi-directional
drift when operated on zero gas. The magnitude of the drift will be a
function of the temperature differential experienced by the analyzer. To
check the circuit, employ the following procedure:

Consult the 4020 schematic and assembly drawings, as well as the
temperature control PC board schematic and assembly drawings at the
rear of the manual for circuit details and component placement.

An indicator light on the control panel cycles on and off with the
heating element; the light is on when the heater is on, and vice versa.
Failure of the light to come on at all when the cell compartment is cold
indicates a problem in the temperature sensing or control circuitry or the
wiring that interconnects the thermistor to the circuit. If the light stays
on constantly, but the compartment does not heat up, then a problem
with the heating element or connecting wiring is indicated.

1. Check the sensing thermistor by measuring the resistance

between its connecting wires. Disconnect one of the thermistor
wires from terminal strip on the temperature controller board,
P/N B30927, the wires out of the thermistor are yellow, and
measure resistance between that wire and the remaining
undisturbed terminal. Resistance of the thermistor varies with its
surrounding temperature. A reading of between 10KOhms and
16Kohms at around 25 °C may be measured. (Under very cold
conditions, the resistance could be as high as 50KOhms; under
hot conditions, just a few thousand ohms.) If the thermistor
measures anywhere in this range, it is most likely OK.
Otherwise, if the circuit is short or open, check the wires leading
to the thermistor,

2. Check the heating element by measuring its resistance.

Disconnect one of the heater wires from either terminal 2 or

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terminal 4 on the temperature control board P/N B30927, heater
wires are black, and check the resistance between that wire and
the remaining undisturbed terminal. If a reading of
approximately 100 Ohms, then the heating element is most likely
OK. If an open circuit is found, check the heater wires and a
possible connector between the heater and temperature control
board. If no problems are found, and the heater circuit is open,
then replace the heater element.

Note: If any of the components located inside the isothermal

chamber has failed, the instrument must be removed for
service. If no problems are found with either the thermistor
or the heater circuits, then replace the temperature control
board.

5.3 Ignition and/or Flame Guard Circuit Checks

If the flame guard circuit will not hold the flame-out lamp off when
the ignition procedure is employed (see section 4.5 Flame Ignition),
perform the following procedure to isolate the problem (consult the
system schematic for details of the circuit):

1. Disconnect the anode-igniter/flame guard thermistor cable from

the socket.

2. Check the flame guard sensing thermistor by measuring the

resistance between pins J4-3&4 of PCB part number B74671,
disconnect the cable plug. The reading should be about 100 KΩ at
room temperature. The actual resis tance is no t importan t, sinc e the
thermistor experiences radical changes in resistance as the
temperature changes. No indication in a sufficiently high range on
the ohmmeter indicates an open thermistor. (If the thermistor is hot,
the resistance will be much lower.)

3. Check the anode-igniter coil for continuity by measuring

between pins J4-1&2 of the disconnected cable plug. The
ohmmeter should indicate a short circuit.

4. If either step 2 or 3 does not check as indicated, remove the

electrode assembly of the detection cell and replace it. If the
quartz flame tip is damaged, the top section of the cell may be
removed by disconnecting the vent line, and removing the screws
around its flange. Return the unit complete with attached

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electrode cable. If steps 2 and 3 both check out properly,
reconnect the anode-igniter cable.

5. Check K1 and K2 relays operation as the analyzer is RE-

IGNITING. If the relays do not energize , remove the flame
guard power supply board and check the forward and backward
resistance of its transient suppression diode by measuring across
CR4 and CR5. The ohmmeter should indicate some resistance .
If the indication a short circuit, then the diode must be replaced.

Note: If, after replacing a defective diode, the circuit still does not

work properly, the flame guard circuit components have
been damaged, and the PC board must be replaced.

6. If the preceding steps check out correctly, the flame guard

portion of the circuitry on the flame guard/anode power supply
PC board is defective.

IMPORTANT: If the circuit proves defective, the analyzer will have

to be recalibrated after the board is replaced.

5.4 Sampling System

If the procedures outlined above do not correct the problem, the fault
must be related to the gas control systems. Plugged or faulty regulators,
plugged restrictors, or leaks within the system can cause erratic
performance. TAI recommends that the factory or an authorized
representative be contacted before attempting any repairs to the sample
or supporting gas systems within the analyzer.

5.5 Printed Circuit Board Descriptions

The electronics circuitry of the analyzer is designed with the latest
integrated circuit technology. The individual circuits which are required
to process the incoming signal and condition it to provide the various
outputs, alarms, indicators, etc.,

5.5.1 Flame Guard and Anode Power Supply PCB

Schematic No. B-74672
Assembly Dwg. No.B-74671

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Anode Power Supply: The high voltage anode power supply
components are mounted on the flame guard and anode power supply
printed circuit board. High voltage regulation is achieved through the
use of zener diodes. The simplicity of this circuit’s design can be
attributed to the extremely low current demand of the anode circuit. The
positive output voltage is nominally 125 volts. Output tolerance is ±10
volts from the specified 250 volts, due to variation in components from
unit to unit.

Flame Guard Circuit: A thermistor-controlled, comparator circuit is
employed to operate relays in the event of a flame-out condition. A
panel indicator light is turned on by the relay to alarm personnel that a
flame-out condition has occurred.

The controlling thermistor is located within the upper section of the
cell assembly. The electronic circuit components and relays are mounted
on the same printed circuit board as the anode power supply. the
indicator light on the control panel.

The thermistor is located in the circuit so that it controls the input of
comparator. The circuit is factory set so that with the flame burning, the
output of comparator is low. The microprocessor senses the low input
and in turn sends 5VDC to turn on Q1, this holds the relay energized.
When energized, the relay extinguishes the Flame Out indicator light.
Conversely, if the flame goes out, bias to the switching transistor is lost,
the relay drops out, and the Flame Out light receives power through
normally closed contacts.

During ignition, the flame heats the thermistor, holding the relay in
the energized condition and the indicator light off. If the Flame Out light
comes on as the analyzer returns analyzing mode, then the flame is not
burning, and the ignition procedure must be repeated.

5.5.3 Proportional Temperature Controller PCB

Schematic No. B-31077
Assembly Dwg. No. B-30927

The temperature of the chamber to be controlled is regulated by a
thermistor-directed electronic circuit. The thermistor and heating
element are located in the chamber, and the balance of the circuit
components are mounted on the temperature controller printed circuit
board, which plugs into a connector on the motherboard.

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The control temperature is determined by the value of resistor R3
and C3 on the temperature controller printed circuit board, selected (at
the time of manufacture) from the chart on schematic B-31077 to
provide the desired control point.

The thermistor used in the circuit is a negative temperature
coefficient (NTC) device; as the chamber temperature increases, the
resistance of the thermistor decreases, and vice versa.

The resistance of the thermistor in the circuit is compared with the
value of resistor R3; when their resistance is equal, or when the
resistance of R3 is less than that of the thermistor, the heating circuit is
activated.

When a temperature deficiency is sensed by the thermistor,
integrated circuit A1, acting as a zero-crossing switch, applies a pulsed
signal to triac Q1, which in turn applies full wave power to the heating
element.

IC A1 employs a diode limiter, a zero-crossing (threshold) detector,
an on-off sensing amplifier (differential comparator), and a Darlington
output driver (thyristor gating circuit) to provide the basic switching
action. The DC operating voltages for these stages are provided by an
internal power supply, with only capacitor C4 added externally.

The on-off sensing amplifier in this circuit is configured as a free­running multivibrator. This scheme adds proportional control, which
takes over when the comparator inputs are at the design differential
voltage.

Initially, when cold, the thermistor resistance is large, and the
voltage at pin 7 is larger than that at pin 8. As the temperature of the
controlled chamber begins to rise, the resistance of the thermistor
decreases, thus reducing the voltage at pin 8. During this warm-up time
the thyristor gating circuit is continuously delivering gate current from
pin 4 of A1, thus maintaining constant fullwave AC power to the heater.

When the temperature reaches the selected control point, pin 13
voltage is about the same as pin 9 voltage, and proportional control takes
over. The rate at which thyristor (triac) Q1 conducts and allows power to
be delivered to the heater is determined by the combination of
components R2 & R3, R4, C3, R5, and the thermistor resistance at the
control temperature. Consequently, the balance point of the bridge
formed by this combination of components can be altered by the

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selection of R3, causing the circuit to seek a temperature at which the
thermistor resistance balances the bridge.

Because IC A1 triggers the thyristor at zero-voltage points in the
supply voltage cycle, transient load current surges and radio frequency
interference (RFI) are substantially reduced. In addition, use of the zero­voltage-switch reduces the rate of change of on-state current (di/dt) in
the thyristor.

5.5.4 Electrometer-Amplifier PCB

Schematic No. B79159
Assembly Dwg. No. B79153

The ions formed in the process of burning hydrogen in the presence
of hydrocarbon components of the sample gas cause an electrical
conduction between two electrodes in the combustion chamber (or
detector cell) that is amplified by a high sensitivity and high input
impedance electrometer-amplifier circuit. The electrical output of the
electrometer-amplifier is directly proportional to the quantity of flame
ionizable hydrocarbons present.

The electrometer amplifier PC board is located on the side of sample
module, interconnected to the electronics circuitry by means of a single
8 pins cable, so that the ease of replacement of a board is maintained.
The high input impedance requires a shield, or cover, which is
removable for access, as well as a shielded input conductor.
Interconnection with the collector is made by a coaxial cable.

Although the cable and fittings are intended for coaxial service,
the cable is actually being used as a shielded single-conductor
connection. The collector cable plugs into a coaxial connector on the
electrometer amplifier PC board, which is located at the side of the
sample mod ule.

The circuit consists of an electrometer amplifier and an operational
amplifier. It is a very high-gain, current-to-voltage converter circuit,
having an input impedance measuring in the billions of ohms. It is static
sensitive and highly susceptible to contamination, and special handling
precautions must be taken.

Because of its high impedance, the input circuitry to the electrometer
has had careful design consideration. The resistors (R2 and R3) in the
input gain circuit (see schematic) are installed on Teflon-insulated

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standoffs, instead of directly to the printed circuit, to elim inate the
possibility of leakage currents.

To eliminate any possibility of contamination of the insulating
materials employed, the completed PC board is ultrasonically cleaned in
laboratory grade alcohol. Under no circumstances should the parts
described be handled with bare fingers. A freshly-scrubbed finger,
stroked along one of the glass resistors, would deposit enough skin oil to
completely upset the range division of the attenuator circuit.

Resistor R3 is a 1000 MΩ resistor used in the feedback circuit of the
amplifier. R2 has a resistance of 10,000 MW and is used in series with
the zero potentiometer slider. This circuit is used to nullify any offset
signal introduced by the signal electrode. Trimmer P1 is used to nullify
the offset signal generated by the electrometer amplifier.

The output of the circuit is standardized against gases with known
hydrocarbon concentrations by zero and span calibration, so that the
meter and/or recorder indicates the hydrocarbon concentration of the gas
being used.

The positive and negative operating voltage required by the
electrometer amplifier is furnished by a switching power supply
circuit,mounting at the back panel of the analyzer

The stability of the electrometer circuit can be tested as follows:

1. Disconnect the collector cable.

2. Place the analyzer in the auto range.

3. Adjust zero offset value so that the recorder reads at some

point upscale, and record a 24 hour chart.

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Total Hydrocarbon Analyzer Appendix

Appendix

Specifications

Fuel: Per application:

- Mixture of 40% hydrogen, 60% nitrogen

- Hydrogen

Accuracy: 1% of full scale
Electronic response time: 90% within one minute
Noise: Less than ±0.5% of full scale
Drift: Less than 1% of full scale per day
Ranges: 3 ranges user defined from 0 ppm to 6%

(methane equivalent)

Sensitivity: As low as 0-1 PPM methane equivalent

full scale

Output: Linear signal; meter readout

0-1 VDC plus 4-20 mA analog output

Ambient temperature: 40 °F to 110 °F (5 °C to 43 °C)
Flow rate: 100-400 ml per minute of sample

100-200 ml per minute of fuel (200 cu. ft.
cylinder lasts about 1 month)

Power requirement: 115 VAC, 60 Hz, single phase
Power consumption: 140 W maximum
Pressure rating: Up to 100 psi
Dimensions: 8.75 " x 19 " x 15.5 " (H x W x D)

222 mm x 483 mm x 394 mm

Weight: 55 lbs.

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Appendix Model 4020

Application Data

Model Number:
Serial Number:
Ranges Of Analysis:
Output Signal:
Start-Up Span Setting:
Control Panel Pressure Settings:
Comments:
Blanket Air:
Fuel:
Sample:
Bypass Flowrate: A minimum of 0.25 SCFH is indicated on

the integral flowmeter

Recommended Support Gases: The accessory gases should all be

laboratory analyzed and certified as to
their hydrocarbon content.

Blanket Air: Water pumped, hydrocarbon free,

compressed air.

Zero Gas: Water pumped, hydrocarbon free

(certified)

Span Gas: ppm methane in (certified)

The span gas contains a known amount of methane impurity. The
span gas must be certified as to its methane equivalent impurity.

IMPORTANT: For the best possible results, zero and span

gases that are representative of the parent (or
background) gas should always be used.

This is particularly true in applications where the analyzer is being used
to analyze a number of different samples with varying concentrations of
oxygen. The geometry and temperature of the flame will be somewhat
dependent on the oxygen content of the sample. Alterations in the flame
configuration will lead to differences in output readings. For the best possible
results, TAI recommends that zero and span gases representative of each of
these samples be used to standardize the analyzer.

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Total Hydrocarbon Analyzer Appendix

Recommended Spare Parts List

Qty. P/N Description

1 B74671 PC board, Flame guard & anode power supply
1 B79153 PC board, Electrometer-amplifier
1 B30927 PC board, Temperature control
1 B79154 Sensor Assembly
1 C75825A Microprocessor PC board
1 CP2540 Coaxial cable
1 C62371A Display PCB Assy.
1 B74674A Interface to Motherboard PCB Assy.
1 C65507A Backpanel/Power Supply PCB Assy.
1 L79 Lamp, neon
5 F10 Fuse, 2A (220V uses F9)
1 L156 Lens, red
1 L154 LED, red
1 A33748 Thermistor assembly

A minimum charge of US $20.00 is applicable to spare parts orders.

IMPORTANT: Orders for replacement parts should include the part number
and the model and serial number of the system for which the parts are
intended.

Send orders to:

TELEDYNE INSTRUMENTS
Analytical Instruments

16830 Chestnut Street
City of Industry, CA 91749-1580

Telephone: [phone]
Fax: [phone]

Web: www.teledyne-ai.com
or your local representative.

Email: [e-mail]

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Appendix Model 4020

Drawing List

D75508 Outline diagram
B75509 Piping diagram
B79159 Schematic, Electrometer PC board
B74672 Schematic, Flame guard, anode power supply PC

board
B31077 Schematic, Temp. controller PC board
D65506 Schematic, Backpanel/Power supply PC board
D79161 Wiring diagram, 19" rack standard

Assemblies

D79158 Assembly, sensor

PC Board Assemblies

B74671 PCB Assy, anode power supply, flame guard
B30927 PCB Assy, temperature controller, 110V
B79153 PCB Assy, electrometer
C75825A PCB Microprocessor
C65507A PCB power supply

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