Teledyne 3060e User manual

Teledyne Electronic Technologies

Analytical Instruments

i

Ultra Trace Sensor Model 3060E

MODEL 3060E

ULTRA TRACE OXYGEN ANALYZER

INSTRUCTION MANUAL

P/N M59174

Software Version 4.22

Edition: M59174-94-554

ECO# 96-385

May 24, 1996

TELEDYNE BROWN ENGINEERING

Analytical Instruments

TELEDYNE BROWN ENGINEERING

Analytical Instruments

MODEL 3060E

Ultra Trace Oxygen Analyzer

MODEL 3060E

Ultra Trace Oxygen Analyzer

Teledyne Electronic Technologies

Analytical Instruments

Model 3060E Ultra Trace Sensor

ii

transcribed, stored in a retrieval system, or translated into any other language or com-

puter language in whole or in part, in any form or by any means, whether it be elec-

tronic, mechanical, magnetic, optical, manual, or otherwise, without the prior written

consent of Teledyne Brown Engineering 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, and serves as a tool by

which 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, with the

process being measured, be properly trained in the process itself, as well as all instru-

mentation 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 Electronic Technologies/Analytical Instruments (TET/AI), 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.

Teledyne Electronic Technologies

Analytical Instruments

iii

Ultra Trace Sensor Model 3060E

Table of Contents

1 Introduction

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

Components ........................................................................................................ 1-2

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

Applications........................................................................................................ 1-4

2 Operational Theory

Overview .............................................................................................................2-1

Ultra Trace Sensor ..............................................................................................2-3

Ultra Trace Sensor Components ..................................................................2-3

Ultra Trace Sensor Operation ......................................................................2-4

Faradaic Calibrator .............................................................................................2-5

Faradaic Calibrator Components .................................................................2-5

Faradaic Calibrator Operation .....................................................................2-7

Sample System .................................................................................................... 2-8

Electronics ...........................................................................................................2-11

Signal Processing Functions.........................................................................2-12

Analog Input Circuit Board .................................................................2-12

AnalogOutput Circuit Board................................................................2-12

Digital Circuit Board ...........................................................................2-14

Display Screens....................................................................................2-14

Temperature Controller ................................................................................2-15

Valve Control Circuit Board ........................................................................2-15

Power Supply Module..................................................................................2-15

3 Installation

Overview .............................................................................................................3-1

Unpacking the Analyzer ......................................................................................3-1

Cautions and Warnings .......................................................................................3-2

Ultra Trace Sensor Installation............................................................................3-3

Adding Electrolyte to the Ultra Trace Sensor ..............................................3-4

Ultra Trace Sensor Electrical Connections ..................................................3-8

Teledyne Electronic Technologies

Analytical Instruments

Model 3060E Ultra Trace Sensor

iv

Faradaic Calibrator .............................................................................................3-9

Adding Electrolyte to the Calibrator ............................................................3-10

Adding Water to the Reservoir.....................................................................3-14

Level Detector and Solenoid Switch ............................................................3-15

Electrical Installation ........................................................................................... 3-16

Electrical Connections ..................................................................................3-16

Voltage Selection and Fuse Changing ..........................................................3-17

Gas Line Connections..........................................................................................3-19

Installation Checklist ........................................................................................... 3-22

4 Operations

Overview .............................................................................................................4-1

Front Panel Controls and Indicators ....................................................................4-2

Sample System Status Panel ........................................................................4-2

LED Display ................................................................................................4-3

Computer Control Module ...........................................................................4-3

Sensor Compartment Temperature Controller .............................................4-6

Ultra Trace Sensor Electrolyte Temperature................................................4-6

Rear Panel Connections.......................................................................................4-6

Operating the Analyzer........................................................................................4-7

Start-up Checklist ........................................................................................4-7

Modes of Operation......................................................................................4-8

Cold Start 4-8

Warm Start ..........................................................................................4-9

Full Start Versus Quick Start ..............................................................4-9

Forcing a COLD START by turning Power OFF/ON .......................4-9

Forcing a Cold Start Without First Shutting Down .............................4-10

Full Start Mode ............................................................................................4-11

Full Start Options.........................................................................................4-13

Setup for Internal Calibrator Use (Full Start)......................................4-13

Setup for Span Gas Use (Full Start) ....................................................4-15

Setup for Both Span Gas & Internal Calibrator (Full Start)................4-16

Quick Start Mode.........................................................................................4-20

Analyze Mode ..............................................................................................4-23

Conditioning the Ultra Trace Sensor....................................................4-23

Span Calibration Using an External Span Gas ............................................4-25

Span Calibration Using the Internal Calibrator ...................................4-29

Teledyne Electronic Technologies

Analytical Instruments

v

Ultra Trace Sensor Model 3060E

Zero Calibration...................................................................................4-33

Important Notes on Zero and Span Calibration ...................................4-37

Setup Mode: System Password ....................................................................4-38

Setup: Alarms ......................................................................................4-40

Setup: Auto Settling ............................................................................4-42

Setup: Clock/Scheduled Span or Scheduled Zero ................................4-47

Setup: More Options ............................................................................4-49

Setup: H2O Reservoir ..........................................................................4-52

Setup: Modem ......................................................................................4-54

Setup: Zero/Span Gas Source ..............................................................4-55

Setup: Negative O2 ..............................................................................4-56

Range Mode .................................................................................................4-57

AutoRange Function ............................................................................ 4-57

Manual Range Function.......................................................................4-58

Stand-by Mode .............................................................................................4-58

Normal Shutdown ................................................................................4-59

High Current Output Mode ..........................................................................4-60

5 Maintenance & Troubleshooting

Routine Maintenance Checklist ........................................................................... 5-1

Ultra Trace Sensor Maintenance .........................................................................5-1

Adding Distilled Water to the Electrolyte ....................................................5-1

Purging Distilled Water................................................................................5-2

Replacing the Electrolyte in the Ultra Trace Sensor ....................................5-3

Scrubber Maintenance .........................................................................................5-4

Troubleshooting...................................................................................................5-4

Troubleshooting Tables ................................................................................ 5-5

6 Quick Reference

Introduction .........................................................................................................6-1

Cold Start ............................................................................................................6-4

Full Start .............................................................................................................6-5

Quick Start ..........................................................................................................6-6

Span Calibration Using External Gas Source .....................................................6-7

Span Calibration Using Internal Calibrator.........................................................6-8

Zero Calibration ..................................................................................................6-9

Setting the Password ...........................................................................................6-10

Teledyne Electronic Technologies

Analytical Instruments

Model 3060E Ultra Trace Sensor

vi

Setting the Alarms ...............................................................................................6-11

Auto Settling........................................................................................................6-12

Scheduled Zero and Scheduled Span ...................................................................6-13

Filtering, Zero Display, Bypass and Reservoir....................................................6-14

Modem.................................................................................................................6-15

Setup: Zero and Span Gas Source .......................................................................6-16

Negative Oxygen Display ....................................................................................6-17

Auto and Fixed Range .........................................................................................6-18

Standby: Normal Shutdown.................................................................................6-19

Appendix

Specifications ......................................................................................................A-1

Spare Parts List ...................................................................................................A-2

Drawing List........................................................................................................A-3

Material Safety Data Sheets............................................... MSDS-1

Teledyne Electronic Technologies

Analytical Instruments

1–1

IntroductionIntroduction

Introduction

Ultra Ultra

Ultra

TT

T

race Oxygrace Oxyg

race Oxyg

en Analen Anal

en Anal

yzyz

yz

erer

er

Introduction

Overview

The Teledyne Electronic Technologies/Analytical Instruments (TET/AI) Model

3060E Ultra Trace Oxygen Analyzer is a highly sophisticated microprocessor-

based instrument designed to measure the oxygen concentration in a gas

mixture in a range as low as 0-50 parts per billion (PPB). The 3060E accurately

measures and analyzes the oxygen content in inert gases such as helium,

nitrogen and argon, and in flammable gases such as hydrogen and ethylene. The

analyzer is easy to use through LCD menu displays with five touch switches for

operator interface.

Figure 1-1: Model 3060E Front Panel

SENSOR COMPARTMENT

TELEDYNE BROWN ENGINEERING

Analytical Instruments

Model 3060E

ULTRA TRACE OXYGEN ANALYZER

483 mm

13

35

83

51

82

310

35

MV1

OXYGEN

SCRUBBER

FLOW SET

SPARGER

GAS

SELECTOR

SPAN

VENT 1 VENT 2

CALIBRATOR

SAMPLE

CELL

MFC

HE

AR

6

7

1

2

3

4

5

9

MV2

MV3

SAMPLE

BYPASS

CALIBRATOR

BYPASS

N

2

H

2

HO

8

10

1–2

Model 3060EModel 3060E

Model 3060E

Chapter 1Chapter 1

Chapter 1

Teledyne Electronic Technologies

Analytical Instruments

Components

The 3060E is designed to mount in a standard 19-inch rack. All of the

operational controls are easily accessed through the well-marked front panel.

Each of the following components is contained within the analyzer:

• Analysis

Electrochemical Ultra Trace Sensor

Electrochemical Calibrator

Sample System

• Power Supply Module

• Control Module

• LED Display

• Valve Control Board

• Temperature Controller

The external design consists of easily accessible controls and ports. The front

panel consists of:

• LED Display

• LCD Display

• Flow Schematic Display

• Ultra Trace Sensor Access Panel

The back panel ports are:

• Gas Inlet/Outlet Ports

• Electrical Connections

• Water Reservoir Inlet and Drain

Main Features of the Analyzer

The 3060E is highly sophisticated yet simple to use. Useful features help you

to operate the analyzer and also provide you with high quality analysis data.

Below is a list of the main features.

1. Low range (0–50 PPB): This range provides highest resolution and

accuracy for ultra-pure gases. Three other ranges (0–100 PPB, 0–1

PPM, and 0–10 PPM) are also provided to meet your analysis needs.

2. Linearity on all ranges: This feature allows the user to calibrate the

analyzer on any of the four ranges and then analyze the sample gases

for all ranges.

Teledyne Electronic Technologies

Analytical Instruments

1–3

IntroductionIntroduction

Introduction

Ultra Ultra

Ultra

TT

T

race Oxygrace Oxyg

race Oxyg

en Analen Anal

en Anal

yzyz

yz

erer

er

3. AutoRanging with manual override: This feature allows the analyzer

to automatically select the appropriate range for a given measure-

ment. A manual override allows the user to “lock in” a specific

range of interest.

4. Built-in oxygen scrubber: The built-in oxygen scrubber can be used

to:

• Produce the zero gas needed to set the zero point.

• Feed the zero gas to sparge the electrolyte in the Ultra Trace

sensor.

• Feed the zero gas to the Faradaic calibrator to generate a

span gas for adjusting the span level.

Should very high oxygen levels be present in the sample gas, the

automatic scrubber inlet shut-off feature prolongs the life of the

scrubber.

5. Faradaic calibrator: The built-in Faradaic calibrator generates oxy-

gen from PPB levels up to 8 PPM, and allows the user to calibrate

the analyzer. A calibrator gauge logs the amount of time the calibra-

tor is used and notifies you through the LCD display if the calibrator

electrolyte needs refilling.

6. Autozero and Autospan: The analyzer can be set to calibrate itself

(zero and span) at pre-programmed intervals.

7. Span gas port: The analyzer has separate sample and span gas ports,

which allow the installation of an external source of span gas for

calibration without interfering with the sample gas line.

8. A built-in water/electrolyte level detector in the Ultra Trace sensor

signals an automatic water feed to the sensor when the electrolyte

falls below a minimum level.

9. Insensitivity to minor flow changes and mechanical vibrations: The

analyzer output is not affected by minor changes in the flow rate.

10. Built-in correction factors for various gases: Built-in correction

factors for various gases allow you to select nitrogen, argon, helium

or hydrogen as background gases without the need to recalibrate the

mass flow controller.

11. Flow schematic display: This feature allows you to visually verify

the exact status of each of the pneumatic valves in the sampling

system.

1–4

Model 3060EModel 3060E

Model 3060E

Chapter 1Chapter 1

Chapter 1

Teledyne Electronic Technologies

Analytical Instruments

12. Meter readouts (the analyzer includes two meter readouts):

· A red LED readout with large, easy-to-read numerals

displaying oxygen concentration.

· An LCD graphic display which includes alphanumeric

information such as alarms, output, help menus, etc.

13. Minimal maintenance: The electrochemical Ultra Trace sensor in the

analyzer requires virtually no maintenance. Water is automatically

replenished in the Ultra Trace sensor. Replacing the electrolyte is

easily done and does not require removing the Ultra Trace sensor

from the analyzer.

14. Remote capability: The 3060E can be remotely located and con-

trolled from a microcomputer linked to the analyzer by a phone line.

Software provided with the analyzer allows you to control analyzer

functions through menus displayed on the computer.

15. Five direct-reading alarms: Five programmable setpoints and Form

C SPDT relays can be configured to practically any requirement.

16. Isolated 4-20 mADC and 0-1 VDC (negative ground) outputs: Four

signal outputs provide for both oxygen measurement and range

identification.

Applications

The analyzer is an invaluable tool in the following applications and industries:

• Analysis of blanketing gases in semiconductor and electronics

industries.

• Measuring the purity of various gases in air separation plants.

• Controlling oxygen for cracking and heating furnaces in petrochemi-

cal industries.

• Prevention of oxidation by measuring the purity of blanketing gases

in fiber and glass industries.

• Monitoring and controlling gas atmospheres in the heat treatment of

metals in steel and other metal industries.

• Gas analysis and research in laboratories and research and develop-

ment areas.

Teledyne Electronic Technologies

Analytical Instruments

2-1

Operational Operational

Operational

TheorTheor

Theor

yy

y

Ultra Ultra

Ultra

TT

T

race Oxygrace Oxyg

race Oxyg

en Analen Anal

en Anal

yzyz

yz

erer

er

Operational Theory

Overview

There are five main analyzer functional groups:

1. Ultra Trace Sensor

2. Faradaic Calibrator

3. Sample System

4. Electronic Signal Processing

5. Temperature Controller.

The analyzer uses a sophisticated Ultra Trace oxygen (O

2

) sensor, which is an

electrochemical galvanic device with current output.

An electrochemical calibrator based on Faraday’s law is provided to facilitate

the calibration of the analyzer.

The sample system is designed to optimize the performance of the analyzer.

The components and the methods used for the fabrication of the sample system

assure leak-free transport of gases through the analyzer.

The electronic signal processing unit (control module) is designed to simplify

the operation of the analyzer and accurately process the signal from various

components. The control module incorporates a microprocessor which allows

the operation of the analyzer with a minimum of operator interaction.

A temperature controller regulates the temperature of the Ultra Trace sensor

to minimize the effects of ambient temperature variations during analysis.

Figure 2-1 shows the locations of the major components of the analyzer.

2-2

Model 3060EModel 3060E

Model 3060E

Chapter 2Chapter 2

Chapter 2

Teledyne Electronic Technologies

Analytical Instruments

Temperature

Controller

Figure 2-1. Main Components

Teledyne Electronic Technologies

Analytical Instruments

2-3

Operational Operational

Operational

TheorTheor

Theor

yy

y

Ultra Ultra

Ultra

TT

T

race Oxygrace Oxyg

race Oxyg

en Analen Anal

en Anal

yzyz

yz

erer

er

Ultra Trace Sensor

The analyzer incorporates an electrochemical ultra trace O

2

sensor exclusively

designed by TET/AI (U.S. Patent #5,085,760). The sensor shows exception-

ally high sensitivity for O

2

and remarkable long-term stability. The highly

accurate sensing element of the sensor enables it to detect as low as 0.5 PPB

of O

2

in a gas mixture.

Ultra Trace Sensor Components

The components of the sensor are shown in Figure 2-2. The main body of the

sensor is made of clear acrylic. The sensor has a U-shaped profile with an open

top end. The left-hand wall of the sensor has a circular aperture for mounting

the O

2

-sensing cathode. A high surface area cadmium anode is inserted through

the top stainless steel plate. A fine porous frit disc is mounted at the bottom of

the sensor in order to remove any dissolved O

2

by continuously sparging the

electrolyte with O

2

free gas. A baffle plate is inserted between the sparger and

the sensing electrode to minimize the noise level caused by the sparger.

The main body of the sensor contains 15% aqueous KOH electrolyte. A

thermistor is inserted into the sensor’s main body through an opening on the top

stainless steel mounting plate. The opening serves as a port for adding water/

electrolyte to the sensor. An electrolyte level detector is also mounted through

the top stainless steel plate.

PURGE GAS OUT

WATER LEVEL

DETECTOR

PURGE GAS IN

TOP STAINLESS

STEEL PLATE

CELL BODY

CATHODE

(+)

SIDE STAINLESS

STEEL PLATE

SAMPLE OUT

SAMPLE IN

CATHODE

O-RING

THERMISTOR

(-)

ELECTROLYTE

ZERO GAS BUBBLES

(OXYGEN-FREE)

CADMIUM ANODE

BAFFLE PLATE

Figure 2-2. Ultra Trace Sensor Components

2-4

Model 3060EModel 3060E

Model 3060E

Chapter 2Chapter 2

Chapter 2

Teledyne Electronic Technologies

Analytical Instruments

The sensing cathode used in the sensor is a high surface-area metal-catalyzed

gas diffusion electrode, with a surface area of 150–180 m

2

/g. A 0.4 mg/cm

2

catalyst load provides an effective cathode surface area of up to 600 times the

geometric area of the cathode. This produces a very high signal output per unit

concentration of O

2

; hence, an excellent signal-to-noise ratio is achieved even

at the highest sensitivity.

The metal-catalyzed gas-diffusion electrode consists of a hydrophobic Teflon-

carbon gas diffusion backing layer and a Teflon-carbon metal catalyst layer

bonded together. The thickness of the catalyst layer is approximately one-tenth

of the gas diffusion layer. The overall thickness of the cathode is approximately

0.5 mm.

The cathode is held against the sensor body by a polyethylene ring. The catalyst

layer of the cathode is exposed to the electrolyte phase; the hydrophobic

backing layer is exposed to the gas to be analyzed. The cathode assembly is

sealed by placing a polypropylene O-ring between the stainless steel plate,

containing stainless steel gas inlet and outlet tubes, and the sensor body.

The electrolyte in the sensor is continuously purged by bubbling the zero gas

(generated by passing the sample gas through the built-in scrubber) through the

fine porous frit mounted in the inner floor of the sensor. Sparging of the

electrolyte removes most of the dissolved O

2

from the electrolyte, reducing the

background signal.

Ultra Trace Sensor Operation

The gas to be analyzed enters the cavity through an inlet tube between the

cathode and the stainless steel plate, and exits through the outlet tube. During

this process, the gas diffuses through the gas wicks of the hydrophobic backing

layer, and reaches the catalyst surface where O

2

present in the gas mixture reacts

by the following mechanism:

O

2

+ 2H

2

O + 4e

-

→ 4OH

-

(cathode)

Due to the high surface area of the catalyst, most of the O

2

reacts at the cathode

surface and a very small amount of O

2

dissolves in the bulk electrolyte. The

continuous sparging of the electrolyte with zero gas does not allow the O

2

concentration to build up in the bulk electrolyte. The amount of O

2

that reaches

the catalyst surface is proportional to the partial pressure of O

2

in the gas

mixture.

Teledyne Electronic Technologies

Analytical Instruments

2-5

Operational Operational

Operational

TheorTheor

Theor

yy

y

Ultra Ultra

Ultra

TT

T

race Oxygrace Oxyg

race Oxyg

en Analen Anal

en Anal

yzyz

yz

erer

er

When the O

2

is reduced at the cathode, cadmium is simultaneously oxidized by

the following mechanism:

Cd → Cd

+2

+ 2e

-

(anode)

The electrons released at the anode surface flow to the cathode surface via an

external circuit. This current is measured and used to determine the O

2

concentration in the gas mixture. The resulting current is directly proportional

to the O

2

level in the gas mixture.

The current output of the sensor changes with temperature therefore, in order

to minimize the effects of ambient temperature variation on the current output,

the sensor is housed in a temperature-controlled oven maintained at 28°C

±2°C. Variations in temperature affecting the sensor are detected by a resistive

thermal device (RTD) attached to the sensor, which signals the temperature

controller to adjust the oven temperature accordingly.

A thermistor installed in the sensor monitors electrolyte temperature. Changes

in electrolyte temperature above 30°C are relayed to the microprocessor, which

adjusts the current output through a compensation algorithm.

NOTE: Since the gas to be analyzed does not flow through the bulk

electrolyte of the sensor, the probability of contaminating the

electrolyte by the particulates (if any) in the sample gas is very low.

This eliminates the requirements for frequent replacement of

sensor electrolyte. This is in contrast to Hercsh type galvanic cells

where gas is bubbled through the electrolyte and frequent replace-

ment of electrolyte (3-6 month intervals) is essential to maintain

sensor performance.

Faradaic Calibrator

The analyzer may be calibrated by using either the internal Faradaic calibrator

or an external span gas. The calibration using an external span gas is simple and

self-explanatory. The internal calibrator generates O

2

at a precisely controlled

rate. The unique design of the calibrator allows repeated and reliable calibration

of the analyzer.

Faradaic Calibrator Components

Figure 2-3 illustrates major calibrator components. The calibrator is comprised

of a top electrode assembly and a bottom mounting block containing a cup for

electrolyte. An O-ring is used to make a leak-free seal between these two

components.

2-6

Model 3060EModel 3060E

Model 3060E

Chapter 2Chapter 2

Chapter 2

Teledyne Electronic Technologies

Analytical Instruments

The two platinum/gold wire electrodes are attached to a feed-through header,

which is sealed to the stainless steel plate. The two electrodes are wrapped

around a porous polyethylene rod. The bottom end of the porous polyethylene

rod is submerged into the pool of electrolyte. Capillary action causes the

electrolyte to fill the pores, keeping the electrodes wet, which helps to maintain

the ionic conductivity between the two electrodes.

PPB OXYGEN

P

O

W

E

R

O

N

C

O

N

T

R

O

L

M

O

D

U

L

E

TE

LE

DYN

E

A

NA

LYTIC

AL

INS

TR

UM

EN

TS

P

M

O

X

Y

G

E

N

Figure 2-3. Major Calibrator Components

Teledyne Electronic Technologies

Analytical Instruments

2-7

Operational Operational

Operational

TheorTheor

Theor

yy

y

Ultra Ultra

Ultra

TT

T

race Oxygrace Oxyg

race Oxyg

en Analen Anal

en Anal

yzyz

yz

erer

er

Faradaic Calibrator Operation

The calibrator is based on Faraday’s Law of Electrolysis. When applied to the

electrolysis of water, it states that the rate at which oxygen is generated is

directly proportional to the quantity of electric current flowing through the

electrodes. Based on this, the following formula is derived to determine the

current required to generate a mixture with the desired oxygen concentration

(PPM) and flow rate (SCCM).

I (

µµ

µA) = 40/150 X O

2

(PPM) X Flow Rate (SCCM)

The desired O

2

concentration is entered through the calibration menu, and the

mass flow controller provides the flow rate of O

2

-free zero gas through the

calibrator. The required current for the electrolysis of water is calculated by the

microprocessor and then supplied to the calibrator electrodes.

A calibrator bypass uses zero gas to flush out any O

2

that has seeped into the

calibration cavity path, eliminating excess O

2

that might otherwise enter the

sampling system.

The accuracy of the calibration gas formed using the calibrator is best in the

0-10 PPM range. Since the sensor has linear output through all ranges, the

analyzer may be calibrated at one or two ranges above the normal range of

operation.

NOTE: For example, if the analyzer is to be used for analysis in the 0–50

PPB range, calibrate the analyzer in the 0–100 PPB or 0–1 PPM

range to minimize calibration error. At this level, errors due to

mass flow controller calibration, measurement of current from a

current source and current leakage are minimized.

To see why, assume the absolute error during calibration on any range is 2 PPB.

If the analyzer is calibrated at 25 PPB, 2 PPB error constitutes an 8% error in

calibration. However, if the analyzer is calibrated at 80 PPB the calibration

error will be only 2.5%.

2-8

Model 3060EModel 3060E

Model 3060E

Chapter 2Chapter 2

Chapter 2

Teledyne Electronic Technologies

Analytical Instruments

Sample System

The sample system delivers gases to the O

2

sensor from the analyzer rear panel

inlet. Depending on the mode of operation (determined by which valves are

open or closed), either a sample, span or zero gas is delivered.

The 3060E sample system is designed and fabricated to insure that the O

2

concentration of the gas is not altered (except in the O

2

scrubber) as it travels

through the sample system.

• Electropolished 316L Stainless Steel Components

To eliminate O

2

absorption and desorption from the internal wetted

surfaces of the sample system components, the sample system is

fabricated from electropolished 316L stainless steel.

• Welding/Metal Gasket-Type Fittings

All of the joints upstream of the O

2

sensor are orbitally welded,

except for the metal gasket-type compression connections at the O

2

scrubber and mass flow controller. Orbital welding is used in the

sample system wherever feasible. Orbital welding fuses the elec-

tropolished 316L stainless steel components together, forming a

smooth, clean internal (wetted) weld junction and eliminating small

spaces around the weld junction where gases can get trapped or

absorbed. All of the weld junctions in the entire assembly are

purged using an inert gas during welding to ensure that there is no

O

2

contamination.

Orbital welding is used where practical; otherwise, conventional

precision welding is used. For example, conventional precision

welding is used to fuse the tubes to the mounting plates. Metal

gasket-type compression connections are used at the O

2

scrubber

and at the mass flow controller to facilitate replacement. The metal

gasket-type connection creates an airtight, metal-to-metal seal,

eliminating inboard and outboard gas leakage.

Teledyne Electronic Technologies

Analytical Instruments

2-9

Operational Operational

Operational

TheorTheor

Theor

yy

y

Ultra Ultra

Ultra

TT

T

race Oxygrace Oxyg

race Oxyg

en Analen Anal

en Anal

yzyz

yz

erer

er

• Valves

The analyzer sampling system utilizes three different types of valves.

Each valve is selected to prevent O

2

contamination of the sample

depending on its position and purpose in the circuit.

Air-Actuated Bellows Valves

These valves are normally closed in the sample system. They are

used to control the delivery through the sample system of the

sample, span or zero gas. The valve bodies are orbitally welded

in the system and the valve bonnets make a metal-to-metal seal

to the body. This valve system eliminates inboard and outboard

gas leakage. The valves are activated (open/closed) by com-

puter-controlled solenoid valves.

The valves have the following basic functions:

PV1: Sample gas to the Ultra Trace sensor.

PV2: Zero gas to the Ultra Trace sensor.

PV3: Zero gas to the calibrator.

PV4: Span gas out of the calibrator.

PV5: External span gas to the Ultra Trace sensor.

PV6: Sample gas into the scrubber.

PV7: Zero gas out of the scrubber.

PV8: Sample bypass vent.

PV9: Water to the Ultra Trace sensor.

PV10: Calibration bypass.

Metering Valve

The metering valve (labeled MV1 on the flow schematic) is used

to manually control the sparge rate to the sensor. The body of

the metering valve is orbitally welded and the bonnet is sealed to

the body with metal O-rings. The manual control knob is lo-

cated in the sensor compartment.

Solenoid Valves

The solenoid valves control the air flow to the air-activated

bellows valves. The solenoid valves are controlled by the micro-

processor. When de-energized, the valve outlet is open to

ambient air, allowing the air-activated bellows valve to close.

2-10

Model 3060EModel 3060E

Model 3060E

Chapter 2Chapter 2

Chapter 2

Teledyne Electronic Technologies

Analytical Instruments

• Oxygen Scrubber

The O

2

scrubber is used to remove O

2

(down to less than 1 PPB,

typically 0.5 PPB) from the sample gas. The scrubbed gas is used

for:

Sparging

Electrolyte in the Ultra Trace oxygen sensor is sparged with

oxygen-free gas to reduce dissolved oxygen from the electrolyte.

Zero Calibration

The oxygen-free gas is used to electronically offset the back-

ground signal of the Ultra Trace sensor. This provides a zero

point for the system to measure the oxygen content of the

sample gas during analysis.

Span Calibration Using Internal Calibrator

The oxygen-free gas is mixed with oxygen generated in the

electrochemical calibrator to produce a span gas with a known

oxygen concentration. This provides a span point for the system

to measure the oxygen content of the sample during analysis.

NOTE: The standard O

2

scrubber has a capacity of 80 cc of pure O

2

.

Under normal operating conditions, the scrubber is expected to

last several years. The scrubber is installed in the system using

metal gasket and VCR type fittings.

The life of the scrubber is approximately 10 years when subjected

to an O

2

concentration of 10 PPM at a flow rate of 150 cc/min.

• Mass Flow Controller

A mass flow controller is used to control the rate of gas flowing by

the sensing electrode of the sensor. The flow controller is located

upstream of the sensor. It provides signal input to the electronics in

the control module. The flow rate is displayed on the LCD screen

and is typically set at 150 cc/min.

• Fittings

The electropolished 316L stainless steel tees, elbows and crosses

used in the sampling system are orbitally welded for system integrity.

Small size fittings are used to make the sample system compact and

to minimize total system internal volume.

Page is loading ...

Teledyne 3060e User manual

Related papers

Other documents