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AR 2000
Rheometer
PN 500106.002 Rev. L
Issued January 2007
AR 2000 Operator's Manual
Rheometrics Series
Operator's Manual
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© 2000–2007 by TA Instruments
109 Lukens Drive
New Castle, DE 19720
Notice
The material contained in this manual, and in the online help for the software used to support this instrument,
is believed adequate for the intended use of the instrument. If the instrument or procedures are used for purposes other than those specified herein, confirmation of their suitability must be obtained from TA Instruments.
Otherwise, TA Instruments does not guarantee any results and assumes no obligation or liability. TA Instruments also reserves the right to revise this document and to make changes without notice.
TA Instruments may have patents, patent applications, trademarks, copyrights, or other intellectual property
covering subject matter in this document. Except as expressly provided in written license agreement from TA
Instrument, the furnishing of this document does not give you any license to these patents, trademarks, copyrights, or other intellectual property.
TA Instruments Operating Software, as well as Module, Data Analysis, and Utility Software and their associated manuals and online help, are proprietary and copyrighted by TA Instruments. Purchasers are granted a
license to use these software programs on the module and controller with which they were purchased. These
programs may not be duplicated by the purchaser without the prior written consent of TA Instruments. Each
licensed program shall remain the exclusive property of TA Instruments, and no rights or licenses are granted to
the purchaser other than as specified above.
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Important: TA Instruments Manual Supplement
Please click on the links below to access important information supplemental to this
Getting Started Guide:
TA Instruments Trademarks
•
•
TA Instruments Patents
• Other Trademarks
• TA Instruments End-User License Agreement
• TA Instruments Offices
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Table of Contents
Important: TA Instruments Manual Supplement........................................................................................................ 3
Table of Contents ............................................................................................................................................................. 4
Notes, Cautions, and Warnings .................................................................................................................................. 10
Chapter 1: Introducing the AR 2000
Overview ........................................................................................................................................................................ 11
Warnings ........................................................................................................................................................................ 11
Attention......................................................................................................................................................................... 13
Safety and EMC Conformity ........................................................................................................................................ 15
Specifications ................................................................................................................................................................. 15
Safety .......................................................................................................................................................................15
EMC ......................................................................................................................................................................... 15
La sûreté et EMC Conformité .......................................................................................................................................16
Spécifications ................................................................................................................................................................. 16
Sûreté ....................................................................................................................................................................... 16
EMC ......................................................................................................................................................................... 16
Lifting and Carrying Instructions ........................................................................................................................ 17
Electrical Safety ...................................................................................................................................................... 17
Liquid Nitrogen Safety .......................................................................................................................................... 18
Handling Liquid Nitrogen ...........................................................................................................................................19
If a Person is Burned by Liquid Nitrogen ............................................................................................................19
......................................................................................................................... 11
Chemical Safety ............................................................................................................................................................. 19
Usage Instructions ........................................................................................................................................................20
Maintenance and Repair ..............................................................................................................................................20
Chapter 2: Description of the AR 2000 ..................................................................................................................... 21
Overview ........................................................................................................................................................................21
A Brief History of Controlled-Stress Rheometers ................................................................................................21
TA Instruments AR Rheometers .................................................................................................................................. 22
Schematics of the AR 2000 Rheometer ................................................................................................................ 22
Instrument Components........................................................................................................................................23
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Chapter 3: Technical Descriptions ............................................................................................................................ 25
Overview ........................................................................................................................................................................
25
The Air Bearing .............................................................................................................................................................25
Rotational Mapping .............................................................................................................................................. 26
Auto GapSet Mechanism.............................................................................................................................................. 27
Zeroing of the Gap ................................................................................................................................................. 27
Closing the Gap ......................................................................................................................................................27
Thermal Compensation .........................................................................................................................................27
Smart Swap™ ................................................................................................................................................................ 28
The Peltier Plate ............................................................................................................................................................. 28
Normal Force Transducer............................................................................................................................................. 29
Chapter 4: Technical Specifications ......................................................................................................................... 31
Overview ........................................................................................................................................................................31
Specifications .................................................................................................................................................................31
Chapter 5: Installation and Operation ......................................................................................................................35
Overview ........................................................................................................................................................................35
Removing the Packaging and Preparing for Installation ......................................................................................... 35
Installation Requirements ............................................................................................................................................ 36
Connecting the System Together.................................................................................................................................. 37
Connecting the Rheometer to the Electronics Control Box ................................................................................37
Connecting the Computerto the Electronics Control Box ..................................................................................37
Connecting Air and Water to the Rheometer ...................................................................................................... 38
Using Smart Swap™ .....................................................................................................................................................39
Installing the Peltier Plate ..................................................................................................................................... 39
Removing the Peltier Plate .................................................................................................................................... 40
Setting Up the Concentric Cylinder System ............................................................................................................... 41
Changing the Cup ..................................................................................................................................................42
Using the ETC ................................................................................................................................................................43
Installing the Low Temperature Accessory......................................................................................................... 46
Operating Hints .....................................................................................................................................................49
Controlling Cooling ........................................................................................................................................ 49
Low Temperature System Maintenance ....................................................................................................... 49
General Operating Guidelines..................................................................................................................................... 50
Do............................................................................................................................................................................. 50
Do Not ..................................................................................................................................................................... 50
Keypad Functionality ................................................................................................................................................... 51
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Levelling the Rheometer ............................................................................................................................................... 52
Checking Your System .................................................................................................................................................. 52
Calibrating the Rheometer ........................................................................................................................................... 53
Shut-Down Procedure .................................................................................................................................................. 53
Cleaning the Filter Regulator Assembly ..................................................................................................................... 54
Chapter 6: Measuring Systems ..................................................................................................................................
55
Overview ........................................................................................................................................................................55
General Description ...................................................................................................................................................... 55
Geometry Materials ................................................................................................................................................55
Stainless Steel .................................................................................................................................................. 55
Aluminium ...................................................................................................................................................... 55
Plastic ...............................................................................................................................................................56
Cone and Plate ...............................................................................................................................................................56
Parallel Plate .................................................................................................................................................................. 57
Concentric Cylinders .................................................................................................................................................... 58
Using the Stress and Shear Rate Factors ....................................................................................................................59
Choosing the Best Geometry ........................................................................................................................................ 60
Cone and Plate/Parallel........................................................................................................................................ 60
Plate Systems .......................................................................................................................................................... 60
Angles ..............................................................................................................................................................60
Diameters ......................................................................................................................................................... 60
Material ............................................................................................................................................................ 61
Preventing Solvent Evaporation .................................................................................................................................. 62
Preventing Slippage at Sample/Geometry Interface ................................................................................................. 62
Removing the Air-Bearing Clamp ............................................................................................................................... 63
Attaching a Geometry ................................................................................................................................................... 64
Ensuring that the Sample is Loaded Correctly .......................................................................................................... 65
Chapter 7: Using the Upper Heated Plate ................................................................................................................ 67
Introduction to the Upper Heated Plate ......................................................................................................................67
Attaching the Upper Heated Plate to the AR 2000 .................................................................................................... 68
Installing the (Optional) Vortex Air Cooler ......................................................................................................... 70
Configurations for the Cooling Water .................................................................................................................. 72
Connecting the Cooling Control Unit........................................................................................................... 73
Using Circulating Fluids Other Than Water ............................................................................................... 74
Connecting and Disconnecting the Geometry Holder ....................................................................................... 76
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Connecting the Geometry and Holder.......................................................................................................... 76
Removing the Geometry and Holder ............................................................................................................ 76
Configuring the Upper Heated Plate ................................................................................................................... 77
Calibration of the Upper Heated Plate........................................................................................................................78
Clamping the Air Bearing ............................................................................................................................................81
Using an Inert Gas Atmosphere .................................................................................................................................. 82
Using the Sample Cover ...............................................................................................................................................83
Chapter 8: The Pressure Cell .....................................................................................................................................
85
Overview ........................................................................................................................................................................85
Specifications .................................................................................................................................................................86
Operating Specifications ....................................................................................................................................... 86
Safety Specifications .............................................................................................................................................. 86
Operational Limits................................................................................................................................................. 86
Pressure Cell Components ........................................................................................................................................... 87
The Pressure Cell Cup ........................................................................................................................................... 88
The Inlet Port ................................................................................................................................................... 88
The Pressure Gauge Port ................................................................................................................................ 88
Safety Relief Port ............................................................................................................................................. 89
Rotor Assembly ...................................................................................................................................................... 89
Magnet Assembly ...................................................................................................................................................90
Pressure Manifold .................................................................................................................................................. 91
Requirements for External Pressure Source ........................................................................................................ 92
Installing and Using the Pressure Cell ....................................................................................................................... 93
Step 1: Install High-Pressure Piping Manifold ..................................................................................................94
Step 2: Install and Configure Pressure Cell Cup and Rotor .............................................................................. 95
Step 3: Positioning Gap and Pressure Cell Calibrations ................................................................................... 97
Step 4: Loading a Sample ...................................................................................................................................... 98
Step 5: Align Manifold and Make Manifold Connections ..............................................................................100
Step 6: Pressurizing/Depressurizing the Cell and Running Experiments ...................................................101
Running Experiments in Self-Pressurization Mode ...............................................................................................102
Running Experiments in External Pressurization Mode .......................................................................................104
Maintaining the Cell ................................................................................................................................................... 106
Cleaning the Pressure Cell Cup ..........................................................................................................................106
Cleaning the Rotor Assembly ............................................................................................................................. 106
Disassembling the Rotor ..............................................................................................................................107
Reassembling the Rotor ................................................................................................................................108
Replacement Parts....................................................................................................................................................... 110
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Chapter 9: AR 2000 Interfacial Accessory.............................................................................................................. 111
Overview ......................................................................................................................................................................
111
Specifications ............................................................................................................................................................... 112
Setting up the Interfacial Accessory .......................................................................................................................... 113
Calibration and Mapping .......................................................................................................................................... 114
Zeroing the Gap ................................................................................................................................................... 114
Mapping and Other Calibrations....................................................................................................................... 114
Experimental Procedure ............................................................................................................................................. 115
Determining Each Fluid's Contribution ............................................................................................................ 115
Finding the Interface Position............................................................................................................................. 116
Analyzing the Results ................................................................................................................................................ 118
Calculation of the Interfacial Contribution to the Torque................................................................................ 118
Interfacial Shear Stress and Shear Rate Calculation ........................................................................................119
Part Numbers ............................................................................................................................................................... 119
References .................................................................................................................................................................... 119
Chapter 10: Do's and Don'ts ....................................................................................................................................121
Overview ......................................................................................................................................................................121
DO.......................................................................................................................................................................... 121
DON'T ...................................................................................................................................................................122
Appendix A: Useful Information ............................................................................................................................123
Moments of Inertia ......................................................................................................................................................123
Calculations for Moments of Inertia ..................................................................................................................123
Cone ................................................................................................................................................................123
Cylinder .........................................................................................................................................................124
Appendix B: Symbols and Units .............................................................................................................................125
Appendix C: Geometry Form Factors ..................................................................................................................... 127
Cone/Plates ................................................................................................................................................................. 127
Concentric Cylinder Dimensions ....................................................................................................................... 127
Appendix D: LCD Display Messages .................................................................................................................... 129
Power On Messages .................................................................................................................................................... 129
Initialising ... ......................................................................................................................................................... 129
Bearing overspeed ................................................................................................................................................129
Bearing pressure too low .....................................................................................................................................130
Encoder index not found ..................................................................................................................................... 130
Nf gauge fault ....................................................................................................................................................... 130
Nf temp sensor fault ............................................................................................................................................130
Operator stop event ..............................................................................................................................................130
Power cable fault ..................................................................................................................................................130
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Signal cable fault ..................................................................................................................................................130
Temp sys element fault ........................................................................................................................................ 130
Temp system environment .................................................................................................................................. 130
Temp system sensor fault .................................................................................................................................... 131
Other Messages .................................................................................................................................................... 131
Appendix E: TA Instruments ETC Kits
.................................................................................................................. 133
ETC Torsion Rectangular Kit (543307.901) .......................................................................................................133
ETC Parallel Plate Kit (543306.901) ................................................................................................................... 133
ETC Disp. Parallel Plate Kit (543308.901) ......................................................................................................... 133
Index............................................................................................................................................................................. 135
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Notes, Cautions, and Warnings
The following conventions are used throughout this guide to point out items of importance to you as you read
through the instructions.
A NOTE highlights important information about equipment or procedures.
A CAUTION emphasizes a procedure that may damage equipment or cause loss of
data if not followed correctly.
A WARNING indicates a procedure that may be hazardous to the operator or to the
environment if not followed correctly.
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Chapter 1
Introducing the AR 2000
Overview
The TA Instruments AR 2000 Rheometer is a controlled stress/controlled rate rheometer capable of handling
many different types of samples, using a range of geometry sizes and types.
This manual relates to all hardware aspects of the AR 2000 Rheometer. For complete information on the
operation of the instrument, you may also have to refer to the relevant software manuals supplied with the
instrument.
This chapter describes some important safety information. Please read this information thoroughly before
proceeding.
Warnings
Please make sure that you read the following warnings BEFORE using this equipment. This section contains
information that is vital to the safe operation of the AR 2000.
WARNING: This equipment must not be mounted on a flammable surface if low
flashpoint material is being analyzed.
WARNING: An extraction system may be required if the heating of materials could
lead to liberation of hazardous gasses.
WARNING: It is recommended that this instrument be serviced by trained and skilled
TA Instruments personnel at least once a year.
WARNING: There may be a danger of explosion if the lithium battery is incorrectly
replaced. It should be replaced only with the same type, contact TA Instruments for
information. Dispose of used batteries according to the battery manufacturers instructions. If in doubt, contact TA Instruments.
WARNING: The material used on the top surface of the Peltier plate is hard, chromeplated copper and the material used for the 'skirt' of the Peltier is stainless steel.
Therefore, use an appropriate cleaning material when cleaning the Peltier plate.
WARNING: The internal components of the AR 2000 ETC are all constructed from
chemically resistant materials, and can therefore be cleaned with standard laboratory
solvents. The only exception is the cladding for the thermocouples, which should not
be immersed in a solvent for long periods. Use a small amount of solvent on a soft
cloth and wipe the soiled area gently. This procedure should never be conducted at
any temperature other than ambient.
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WARNING: During the installation or reinstallation of the instrument, ensure that the
external connecting cables (i.e., data, RS232 etc.) are placed separate from the mains
power cables. Also, ensure that the external connecting cables and the mains power
cables are placed away from any hot external parts of the instrument.
Note: Ensure that the mains power cable is selected such that it is suitable for the
instrument that is being installed or reinstalled, paying particular attention to the
current rating of both the cable and the instrument.
WARNING: Before switching the instrument on, apply the air to the instrument and
switch on the water supply to the Peltier system (if used).
WARNING: During operation, extreme hot or cold surfaces may be exposed. Take
adequate precautions. Wear safety gloves before removing hot or cold geometries.
WARNING: Liquid nitrogen can cause rapid suffocation without warning. Store and
use in an area with adequate ventilation. Do not vent liquid nitrogen in confined
spaces. Do not enter confined spaces where nitrogen gas may be present unless the
area is well ventilated. The warning above applies to the use of liquid nitrogen.
Oxygen depletion sensors are sometimes utilized where liquid nitrogen is in use.
WARNING: The various surfaces and pipes of the ETC and the supply Dewar can get
cold during use. These cold surfaces cause condensation and, in some cases, frost to
build up. This condensation may drip to the floor. Provisions to keep the floor dry
should be made. If any moisture does drip to the floor, be sure to clean it up promptly
to prevent a slipping hazard.
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WARNING: Always unplug the instrument before performing any maintenance.
WARNING: No user serviceable parts are contained in the rheometer. Maintenance
and repair must be performed by TA Instruments or other qualified service personnel
only.
WARNING: This instrument must be connected to an earthed (grounded) power
supply. If this instrument is used with an extension lead, the earth (ground) continuity
must be maintained.
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Attention
Cet instrument ne doit être en aucun cas installé sur une surface inflammable lors de
l'analyse d'échantillons ayant un faible point d'éclair.
Une bouche d'extraction est nécessaire lors de la combustion de matériaux libérant
des gaz toxiques.
Il est recommendé que cet appareil soit révisé au moins une fois par an par un
ingénieur TA Instruments.
Les piles au lithium de rechange doivent être impérativement du même type que
celles d'origine. Dans le cas contraire, un risque d'explosion reste possible. Pour plus
d'informations, contacter TA Instruments.
Ne pas jeter de piles au lithium usagées. Celles-ci doivent être recyclées.
La surface supérieure en cuivre de la plaque Peltier est recouverte de chrome. Et la
surface latérale est recouverte d'acier. Il est important d'utiliser des produits adéquats,
lors du nettoyage du Peltier, qui n'altérerons pas ces deux matériaux.
Les composants internes du four (ETC) monté sur l'AR2000 sont conçus pour résister à
toute attaque chimique. Ils peuvent donc être tous nettoyés, à l'aide de solvants
quelconques, à l'exception du revêtement des thermocouples, qui ne doivent pas,
quant à eux, baigner dans un solvant pendant une longue période. Ceux-ci doivent
être nettoyés a température ambiante en frottant légèrement avec un chiffon imbibé
de solvant.
Les cables externes doivent être toujours separés du cable d'alimentation. S'en
assurer à chaque installation. De même, tout cable doit être éloigné de toute source
de chaleur (Peltier…).
Avant toute mise en marche, s'assurer que l'arrivée d'eau pour le Peltier (si utilisé)
ainsi que l'arrivée d'air pour le moteur sont connectées et que l'eau et l'air circulent.
Les différentes surfaces, tuyaux de l’ETC ainsi que le reservoir d’azote liquide peuvent
être exposés à de très basses températures pendant l ’utilisation. Ces surfaces froides
provoquent de la condensation et peuvent même être à l’origine d’une formation de
glace. Cette condensation risque de goutter par terre. Afin d’éviter tout accident dû à
un sol glissant, il serait préférable de garder le sol aussi sec que possible.
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Lors de toute maintenance, couper l'alimentation.
Toute maintenance ou réparation doivent être effectuées par TA Instruments ou un
personnel de service qualifié.
Cet appareil doit être connecté à la terre. Toute rallonge utilisée avec cet appareil
doit comporter une masse de securité.
Utiliser l'azote liquide avec précautions car une utilisation inadéquate peut provoquer
des suffocations. Stocker et utiliser dans une pièce suffisament ventilée. Ne pas
pénétrer dans une pièce remplie d'azote avant d'en avoir evacué le gaz.
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Safety and EMC Conformity Specifications
In order to comply with the European Council Directives, 73/23/EEC (LVD) and 89/336/EEC (EMC Directive),
as amended by 93/68/EEC; the AR 2000 has been tested to the following specifications:
Safety
This equipment has been designed to comply with the following standards on safety:
• EN 61010-1:1993
Safety requirements for electrical equipment for measurement, control and laboratory use.
EN 61010-1 Amendment 1, 1995
EN 61010-1 Amendment 2, 1995
• EN 6101-2-010: 1994
Particular requirements for laboratory equipment for the heating of materials.
EN 61010-2-010 Amendment 1, 1996
• UL3101-1 First Edition 1993
IEC 1010-2-010: 1992
• CAN/CSA-C22.2 No.1010-1: 1992
IEC 1010-2-010: 1992
EMC
• EN61326-1: 1997
Electrical equipment for measurement, control and laboratory use.
Incorporating:
EN55011: 1998 Conducted Class B
EN55011: 1998 Radiated Class A
EN6100-3-2: 1995 Harmonic current
EN6100-3-3: 1995 Voltage flicker
EN6100-4-2: 1995 ESD
EN6100-4-3: 1996 Radiated RF
EN6100-4-4: 1995 Fast Transient/Burst
EN6100-4-5: 1995 Surge
EN6100-4-6: 1996 Conducted disturbances
EN6100-4-11: 1994 Voltage dips
• AZ/NZS 2064: 1997
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La sûreté et EMC Conformité Spécifications
Afin de se conformer aux directives du Conseil européen, 73/23/EEC (LVD) et 89/336/EEC (directive d'cEmc),
comme modifié par 93/68/EEC; l'Ar 2000 a été testé selon les caractéristiques suivantes:
Sûreté
Ce matériel a été conçu pour être conforme aux normes de sécurité suivantes:
• EN 61010-1:1993
Conditions de securité pour l'appareillage de mesures électrique, la commande et l'usage de laboratoire.
EN61010-1 Amendment 1, 1995
EN61010-1 Amendment 2, 1995
• EN6101-2-010: 1994
Conditions particulières pour le matériel de laboratoire destine au chauffage des matériaux.
EN61010-2-010 Amendment 1, 1996
• UL3101-1 First Edition 1993
IEC 1010-2-010: 1992
• CAN/CSA-C22.2 No.1010-1: 1992
IEC 1010-2-010: 1992
EMC
• EN61326-1: 1997
Conditions de securité pour l'appareillage de mesures électrique, la commande et l'usage de laboratoire.
incorporation
EN55011: 1998 Conducted Class B
EN55011: 1998 Radiated Class A
EN6100-3-2: 1995 Harmonic current
EN6100-3-3: 1995 Voltage flicker
EN6100-4-2: 1995 ESD
EN6100-4-3: 1996 Radiated RF
EN6100-4-4: 1995 Fast Transient/Burst
EN6100-4-5: 1995 Surge
EN6100-4-6: 1996 Conducted disturbances
EN6100-4-11: 1994 Voltage dips
• AZ/NZS 2064: 1997
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Lifting and Carrying Instructions
Please follow these recommendations when you move or lift the instrument and its accessories:
• Before moving the rheometer, you should remove any temperature attachments from the Smart Swap™
holder. See Chapter 5 for more information.
• When moving the rheometer, the air-bearing clamp should always be in place, ensuring that the bearing
cannot be moved. See Chapter 5 for information on the air-bearing clamp and how it is attached.
• Use two hands to lift the instrument, keeping your back straight as you lift, to avoid possible strain on your
back. You should always use two people to lift the instrument.
• Treat the AR 2000 with the same degree of care you would take with any scientific laboratory instrument.
Electrical Safety
Always unplug the instrument before performing any maintenance.
Supply Voltage 110 - 240 Vac
Fuse type 2 x F10 A H250v
Mains Frequency 45 to 65 Hz
Power 1000 watts
WARNING: Because of the high voltages in this instrument, maintenance and repair of
internal parts must be performed by TA Instruments or other qualified service personnel only.
Cet instrument etant sous hautes tensions, l'entretien et la réparation des pièces
internes doivent être effectues exclusivement par TA instruments ou tout autre personnel de service qualifié.
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Liquid Nitrogen Safety
Potential Asphyxiant
WARNING: Liquid nitrogen can cause rapid suffocation without warning. Store and
use in an area with adequate ventilation. Do not vent liquid nitrogen in confined
spaces. Do not enter confined spaces where nitrogen gas may be present unless the
area is well ventilated. The warning above applies to the use of liquid nitrogen.
Oxygen depletion sensors are sometimes utilized where liquid nitrogen is in use.
Potentiel Agent asphxyiant
L'azote liquide peut causer des suffocations rapides. Stocker et utiliser dans une zone
dotée d'une ventilation adéquate. Ne pas ventiler d'azote liquide dans des espaces
confinés. Ne pas pénétrer dans des espaces confinés où le gaz d'azote peut être
présent à moins de bien aérer la zone. L'avertissement ci-dessus s'applique à
l'utilisation de l'azote liquide. Des capteurs d'épuisement d'oxygène sont parfois
utilisés.
Extremes of temperature
During operation, extreme hot or cold surfaces may be exposed. Take adequate
precautions. Wear safety gloves before removing hot or cold geometries.
Températures extremes.
Lors du fonctionnement, des surfaces extrèmement chaudes ou froides peuvent être
exposées. Prendre toutes précautions necessaires telles que l'utilisation de gants de
protection avant d'enlever les géométries chaudes ou froides.
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Handling Liquid Nitrogen
The ETC uses the cryogenic (low-temperature) agent, liquid nitrogen, for cooling. Because of its low temperature
[-195°C (-319°F)], liquid nitrogen will burn the skin. When you work with liquid nitrogen, use the following
precautions:
Liquid nitrogen evaporates rapidly at room temperature. Be certain that areas where liquid nitrogen is used are
well ventilated to prevent displacement of oxygen in the air.
1. Wear goggles or a face shield, gloves large enough to be removed easily, and a rubber apron. For extra
protection, wear high-topped, sturdy shoes, and leave your trouser legs outside the tops.
2. Transfer the liquid slowly to prevent thermal shock to the equipment. Use containers that have satisfactory
low-temperature properties. Ensure that closed containers have vents to relieve pressure.
3. The purity of liquid nitrogen decreases as the nitrogen evaporates. If much of the liquid in a container has
evaporated, analyze the remaining liquid before using it for any purpose where high oxygen content could
be dangerous.
The oven inner doors have a trough around the bottom of the element assembly for collection of excess liquid
nitrogen. Any excess fluid collected will drain out from the oven at the lower outer edge.
If a Person is Burned by Liquid Nitrogen
1. IMMEDIATELY flood the area (skin or eyes) with large quantities
of cool water, then apply cold compresses.
2. If the skin is blistered or if there is a chance of eye infection, take
the person to a doctor IMMEDIATELY.
Chemical Safety
Do not use hydrogen or any other explosive gas with the ETC.
Use of chlorine gas will damage the instrument.
If you are using samples that may emit harmful gases, vent the gases by placing the instrument near an exhaust.
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Usage Instructions
Before connecting the rheometer to auxiliary equipment, you must ensure that you have read the relevant
installation information. Safety of the rheometer may be impaired if the instrument:
• Shows visible damage
• Fails to perform the intended measurements
• Has been badly stored
• Has been flooded with water
• Has been subjected to severe transport stresses.
Maintenance and Repair
CAUTION: Adjustment, replacement of parts, maintenance and repair should be
carried out by trained and skilled TA personnel only. The instrument should be
disconnected from the mains before removal of the cover.
Le réglage, le remplacement des pièces, l'entretien et la réparation devraient être
effectués exclusivement par le personnel qualifié de TA Instruments. Avant l'ouverture
du châssis, débrancher l'instrument.
WARNING: The cover should only be removed by authorized personnel. Once the
cover has been removed, live parts are accessible. Both live and neutral supplies are
fused and therefore a failure of a single fuse could still leave some parts live. The
instrument contains capacitors that may remain charged even after being disconnected from the supply.
Le châssis doit être retiré exclusivement par le personnel autorisé. Une fois le chassis
retiré, les pièces connectées à l'alimentation sont accessibles. L'instrument contient
plusieurs fusibles. L'instrument contient des condensateurs qui peuvent rester chargés
même après avoir été débranchés.
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Chapter 2
Description of the AR 2000
Overview
This chapter describes the main components of the rheometer and provides technical information on performance and design. Please read this chapter thoroughly to become familiar with the nomenclature used
throughout this manual.
A Brief History of Controlled-Stress Rheometers
Sir Isaac Newton (c.1700) was the first to formulate a mathematical description of a fluid's resistance to deform
or flow when a stress was applied to it. He described this resistance as the viscosity. It is mathematically
described as the shear stress divided by the shear rate or strain. Until Couette developed the first rotational
viscometer (c.1890), viscosity was measured using stress driven (gravity) flow. Many of today's techniques still
use this principle, such as flow cups, U-tubes, capillaries, etc.
The development of an electromechanical instrument, using synchronous motors, and the electronic versions,
using controlled speed servomotors, made controlled rate the widely used technique for versatile rheological
instruments for many years.
The first controlled-stress instrument, capable of continuous rotation, was developed by Davis, Deer, and
Warburton (1968 J.Sci. Instr. 2, I, 933-6) at the London School of Pharmacy. This instrument used an air turbine
and an air bearing. In the early 1970's, a second generation of instruments was developed, using an induction
motor drive to avoid the problems associated with the air turbine. These, however, were restricted to a maximum torque of 5000 µNm.
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TA Instruments AR Rheometers
The TA Instruments AR Rheometers are fifth-generation instruments that function as either controlled-stress or
controlled-rate instruments.
The rheometers are designed to fulfill the requirements of measurement as implied by the full meaning of the
term rheology—defined as the "study of the deformation and flow of matter."
Deformation is measured in the nondestructive region of elastic or viscoelastic deformation. This can give
invaluable information concerning the microscopic interactions in the test material, as well as measuring the
shear stress/shear rate relationships at higher stresses.
In the controlled-stress technique, the stress can be applied and released at will, and the actual behavior of the
sample can be measured directly. This is not usually possible with conventional controlled-shear rate instruments. In addition, most real-life situations can be simulated more accurately using controlled-stress measurements.
Schematics of the AR 2000 Rheometer
The parts of the AR 2000 are shown
in the figures in this sectiion as
follows:
Figure 2.1 shows a schematic of the
front of the rheometer.
Figure 2.2, shows the control panel.
The rear of the instrument is shown
in Figure 2.3 on the next page.
Figure 2.1
The AR 2000 Rheometer (Front)
22
Figure 2.2
The AR 2000 Rheometer (Control Panel)
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Instrument Components
The instrument consists of a main unit mounted on a
cast metal stand, with the electronic control
circuitry contained within a separate electronics control
box. Figure 2.4 shows the rear of the electronics control
box.
The AR 2000 Rheometer contains an electronicallycontrolled induction motor with an air bearing support
for all the rotating parts. The drive motor has a hollow
spindle with a detachable draw rod inserted through it.
The draw rod has a screw-threaded section at the
bottom, which allows the geometry to be securely
attached.
The measurement of angular displacement is done by an
optical encoder device. This can detect very small
movements down to 40 nRad. The encoder consists of a
non-contacting light source and photocell arranged
either side of a transparent disc attached to the drive
shaft. On the edge of this disc are extremely fine, accurate photographically-etched radial lines. Therefore, this
is a diffraction grating. There is also a stationary
segment of a similar disc between the light source and
encoder disc. The interaction of these two discs results
in diffraction patterns that are detected by the photocell.
Figure 2.3
The AR 2000 Rheometer (Rear)
Figure 2.4
Electronics Control Box (Rear)
As the encoder disc moves when the
sample strains under stress, these patterns
change. The associated circuitry interpolates and digitizes the resulting signal to
produce digital data. This data is directly
related to the angular deflection of the
disc, and, therefore, the strain of the
sample.
The main electronics are housed in a
separate control box. (The interplay
between the rheometer/electronics and
controller are explained in more detail in
Chapter 5.)
Temperature control is achieved via
interchangeable temperature options.
These are discussed in more detail in
Chapter 3.
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Chapter 3
T echnical Descriptions
Overview
In order to fully utilize the advanced capabilities available with the AR 2000 Rheometer, some of the important
components require a more detailed explanation. This chapter describes in detail the design and functions of
the:
• Air bearing
• Auto gap set device
• Smart Swap™
• Peltier plate
• Normal force transducer.
The Air Bearing
As its name suggests, an air bearing uses air as the lubricating medium. This allows virtually friction-free
application of torque.
The design of an air bearing is a compromise between several characteristics such as air consumption, friction,
stiffness, and tolerance to contamination and misuse.
The amount of air consumed is
related to the pressurized bearing
clearance. To minimize air consumption, a small clearance
(<10µm) is needed. However, as air
has a finite viscosity (0.0018
mPa.s), small gaps give rise to high
shear rates and, correspondingly,
the friction increases.
If large gaps are used, the shear rate
is lowered and friction is reduced,
but the stiffness of the air bearing is
also reduced.
Thus, a compromise in the design
of an air bearing is needed for
optimal performance.
The air bearing used in the AR
2000 Rheometer uses a mixture of
proven bearing techniques with
novel materials. The surfaces can
be easily machined to tolerances of
less than 1µm, providing an
extremely smooth finish.
Figure 3.1
The Rheometer Head
A schematic of the Air Bearing and
the other main components of the rheometer head is shown in Figure 3.1 above.
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The bearing is designed to be virtually friction- free, so that it moves under the smallest of forces. Even extremely
small manufacturing variations in the bearing can be sufficient to make it rotate. Therefore, to ensure that the
bearing rotation is steady throughout a full 360°, a process called Rotational Mapping, which is explained in
the next section, is carried out.
Rotational Mapping
As explained previously, any real air bearing will have small variations in behavior around one revolution of
the shaft.
By combining the absolute angular position data from the optical encoder with microprocessor control of the
motor, these small variations can be mapped automatically and stored, since the variations are consistent over
time, unless changes occur in the air bearing.
The microprocessor can allow for these automatically by carrying out a baseline correction of the torque. This
results in a very wide bearing operating range, without operator intervention; i.e., a confidence check in bearing
performance.
Instructions for performing the rotational mapping can be found in the Rheology Advantage™ online help.
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Auto GapSet Mechanism
The auto gap set facility has three major functions, as follows:
• Automatic setting of gaps via software
• Programmed gap closure
• Thermal gap compensation.
These features are described in more detail on the following pages.
Zeroing of the Gap
It is important that you use a reproducible gap zeroing technique to reduce errors from such factors as operatorto-operator techniques. The automation of gap zeroing on the rheometer minimizes these errors.
Closing the Gap
Once you have set the gap and loaded the sample, the head is lowered. The velocity and deceleration of the
head as it is lowered is controlled via the 'automatic gap options' set in the Rheology Advantage software.
There are four closure options available with the AR 2000 Rheometer-—Standard, Linear, Exponential, and
Normal Force. The options available are described in detail in the online help for the rheology software.
CAUTION: Keep hands and fingers away from the plate during head movement.
S'assurer que les mains ou doigts ne soient pas entre le peltier et la
géométrie lors du mouvement de la tête de l'instrument.
Thermal Compensation
When a wide temperature range is used for an experiment, the metallic rheometer parts and the measurement
geometries can heat or cool causing expansion or contraction of the measurement system gap. A typical expansion value for stainless steel geometries is 0.5 µm°C
Therefore, regardless of temperature, you can be confident that the gap remains constant.
-1
. The auto gap-set facility compensates for these changes.
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Smart Swap™
The AR2000 features "Smart Swap" technology that automatically senses the temperature control system present
and configures the rheometer operating software accordingly, loading all relevant calibration data. The use of
this feature is covered later in Chapter 5.
The Peltier Plate
Temperature control in the standard configuration is via a Peltier
system (both a plate and concentric cylinder system are available),
which uses the Peltier effect to rapidly and accurately control heating
and cooling. The Peltier system uses a thermoelectric effect. This
functions as a heat pump system with no moving parts, and is ideally
suited to rheological measurements. By controlling the magnitude and
direction of electric current, the Peltier system can provide any desired
level of active heating or cooling directly in the plate.
A schematic of the Peltier plate is shown in Figure 3.2.
Since the Peltier system operates as a heat pump, it is necessary to
have a heat sink available. The heat sink removes unwanted waste
heat from the plate. This heat sink is normally in the form of a reservoir, containing a few liters of water, plus a small pump that can
provide sufficient flow rate through the Peltier heat exchanger jacket
built into the plate.
The reservoir fluid will become warm with the prolonged use of the
Peltier at high or sub-ambient temperatures.
If your temperature range is 20°C below and 60°C above ambient, the
water bath should be at room temperature. If, however, you wish to
work at lower or higher temperatures, the water bath temperature
needs to be altered accordingly (i.e., the Peltier system will work most
efficiently at a temperature range that is 15°C above and below the water bath temperature.). When routinely
using the Peltier system at temperatures above 100°C, it is recommended that you connect the system to a main
water supply.
The flow rate through the Peltier does not need to be high. A flow rate of at least 0.5 litre min
When working at the Peltier's lowest temperature range, increasing the flow rate to >1 liter min-1 will give a
better performance. If this flow rate is not maintained, the temperature control system will lose control and the
system will only heat.
Peltier Temperature Range
tank & pump -5°C to 100°C
pumped water supply (20°C) -20°C to 200°C
water at 60°C 10°C to 200°C
water at 40°C 0°C to 200°C
water at 1°C -30°C to 180°C
fluid at -20°C -40°C to 160°C
Figure 3.2
The Peltier Plate
-1
is adequate.
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CAUTION: The Peltier Plate may be damaged by operating the instrument without a
flow of water through the Peltier system. There is a Peltier Overheat protection
device that will activate if the device becomes too hot.
Sans écoulement d'eau, le système Peltier peut être endommagé. Un dispositif de
protection a été conçu pour se déclencher en cas de surchauffe.
Normal Force Transducer
When a viscoelastic liquid is sheared, a force can be generated along the axis of rotation of a cone or parallel
plate geometry. For this to happen, the structure responsible for the elasticity must not be completely disrupted
by steady shear.
For this reason, colloids, suspensions, etc., although elastic at rest, become effectively inelastic under steady
shear and can show negative normal forces due to inertial effects. However, polymer solutions and melts, and
products incorporating them, are typically elastic under shear because of the long lifetime of the molecular
entanglement.
Normal force measurements are made with cone and plate or parallel plate geometries; therefore, it is important
to use a method to detect the force that does not allow significant changes in the gap. This would result in the
actual shear rate varying with normal force, due to deflections of the force-detecting component.
The AR 2000 Rheometer keeps the upper geometry positioned as accurately as is possible with an air bearing,
and movement is kept to an absolute minimum. This ensures good bearing performance.
The force is detected on the static lower measuring geometry assembly using high sensitivity load cell technology. This results in a fast response, wide range signal, which is easy to calibrate, and has a genuine normal
force measurement capability.
CAUTION: During sample loading and measurement, the normal force transducer is
protected from overload. However, take care when cleaning or attaching accessories
to the lower plate that you do not exceed the maximum normal force.
Le capteur de force normale est protégé contre toute surcharge. Cependant, prendre
soin de ne pas dépasser la force normale maximale lors de toute manipulation
(nettoyage, changement de plaque…).
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Chapter 4
T echnical Specifications
Overview
This chapter contains the technical specifications for the AR 2000 Rheometer. You can obtain further information from your local Sales Representative.
Specifications
The following specifications apply to the TA Instruments AR 2000 Rheometer:
Table 4.1
AR 2000 Rheometer Dimensions
Accessory (Electronics Base)
Width 7.25 in. (18.5 cm)
Height 14.75 in. (37.5 cm)
Depth 17.75 in. (45 cm)
Weight 38.1 lbs (17.3 kg)
Module (Instrument Base)
Width 11.75 in. (30 cm)
Height 26.5 in. (67 cm)
Depth 12.5 in. (32 cm)
Weight 62.2 lbs (28.7 kg)
Table 4.2
AR 2000 Rheometer Specifications
Supply Voltage 110 – 240 Vac
Supply Frequency 45 to 65 Hz
Power 1000 Watts
Torque Range 0.1 µNm to 200 mNm
Frequency Range 0.12 µHz to 100 Hz
Angular Velocity Range Controlled Stress: 10-8 to 300 Rad s
Controlled Strain: 10-2 to 300 Rad s
(table continued)
-1
-1
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Table 4.2
AR 2000 Rheometer Specifications
Angular Displacement 40 nRad
Resolution
Minimum Strain 0.00006
Normal Force Range 1 g to 5000 g
Table 4.3
Peltier Plate System Specifications
Temperature Range
tank & pump -5°C to 100°C
pumped water supply (20°C) -20°C to 200°C
water at 60°C 10°C to 200°C
water at 40°C 0°C to 200°C
water at 1°C -30°C to 180°C
fluid at -20°C -40°C to 160°C
Typical Ramp Rate 30 °C min
Ramp Rate (20 to 100 °C) 50 °C min
(100 to 150 °C) 25 °C min
-1
-1
-1
Pt100 Internal Resolution 0.01 °C
Table 4.4
Optional Accessory Specifications for
Environmental Test Chamber Module (ETC)
Temperature Range
No cooling 50°C to 600°C
LN2 cooling -150°C to 600°C
Typical Ramp Rate maximum ramp rate 25°C/min
Internal Resolution 0.02 °C
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Table 4.5
Optional Accessory Specifications for
Peltier Concentric Cylinder System
Temperature range
with tank and pump 0°C to 100°C
with plumbed water supply -10°C to 150°C
with fluid at -20°C -40°C to 100°C
Ramp Rate
Cooling 15°C/min maximum
Heating 13°C/min maximum
Pt100 Internal Resolution 0.01 °C
Table 4.6
Optional Accessory Specifications for Upper Heated Plate
Temperature range
plumbed water supply (11°C) 20°C to 150°
low viscosity silicone circulating fluid at -40°C -30°C to 55°C
vortex air cooler -5°C to 150°C
Ramp rate 15°C maximum
Maximum temperature difference between plates 0.1°C
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Chapter 5
Installation and Operation
Overview
Normally the installation of your new system will be carried out by a member of the TA Instruments sales or
service staff, or their appointed agents, and it will be ready for you to use. However, should you need to install
or relocate the instrument, this chapter provides the necessary instructions.
Removing the Packaging and Preparing for Installation
If needed, the first step is to carefully remove all items from any and all packaging. We recommend that you
retain all packaging materials in case the instrument has to be shipped back to TA Instruments at some point in
the future (for example, in the case of some upgrades).
Please follow these recommendations when you move or lift the instrument and its accessories:
• Always remove the temperature control module from the rheometer before attempting to move it. Details on
how to do this can be found later in this section
(Smart Swap™).
• When moving the rheometer, the air-bearing clamp
should always be in place, ensuring that the bearing
cannot be moved.
1. Insert the draw rod into the top of the rheometer.
2. Push the bearing clamp up
onto the draw rod. Hold it in
place while turning the knob at
the top in a clockwise direction.
CAUTION: Always hold the clamp and turn the knob - never the
other way round.
Toujours tenir la géométrie et tourner la molette - jamais le
contraire.
Models with Air Bearing Lock
If the AR 2000 you own has an air bearing lock, follow these
steps:
Figure 5.2
Performing Step 3
1. Insert the draw rod into the top of the rheometer.
2. Next, slide the bearing lock into place (you may need to
turn the shaft so that the flats line up with the lock.)
Figure 5.1
Inserting the Draw Rod
AR 2000 Operator's Manual
3. Push the air-bearing clamp up onto the draw rod. Hold it in place while turning the
knob at the top in a clockwise direction.
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Installation Requirements
It is important to select a location for the instrument using the following guidelines.
Choose a location that is...
In
• A temperature-controlled area. (22°C ±4°C, relative humidity 50 ±10%).
• A clean environment (indoor use).
• An area with ample working and ventilation space around the instrument, approximately 2 meters in
length, with sufficient depth for a computer and its keyboard.
On
• A stable, vibration-free work surface.
Near
• A power outlet. (Mains supply voltage fluctuations not to exceed ±10% of the nominal voltage, installation
category 2.)
• Your computer.
• Sources of compressed lab air and purge gas supply for use during cooling and sub-ambient experiments.
A compressed air supply that is capable of supplying clean, dry, oil free air at an approximate pressure of
30 psi (~ 2 Bar) at a flow rate of 50 liters-1. The dew point of the air supply should be -20°C or better.
Away from
• Dusty environment (pollution degree 1).
• Exposure to direct sunlight.
• Poorly ventilated areas.
After you have decided on the location for your instrument, refer to the following sections to unpack and install
the AR 2000 Rheometer.
NOTE: Internal Fuse: FS1 & FS2 on cmd 069 pcb. It is strongly recommended that the
internal fuse be replaced only by trained and skilled TA Instrument personnel.
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Connecting the System Together
Connecting the system together should present no problems, as long as you use instructions found in the
following sections.
Connecting the Rheometer to the Electronics Control Box
The Electronics Control Box forms the link between the rheometer and
the computer. All the required processing is done within the control box.
The following steps should be followed to connect the two units together
(refer to Figure 5.3).
1. Push the female end of the Power cable into the Power port on the
back of the rheometer and the other end in the Power port on the
back of the control box (Cable A).
2. Push the D-type cable into the Signal port on the back of the rheom-
eter and connect the other end to the Signal port on the back of the
control box (Cable C).
Connecting the Computer to the Electronics Control Box
The electronics control box and computer are connected via a single
RS232 cable, which is supplied with the system. One end of the cable
has a 9-pin female connector; the other end has a 9-pin male connector.
1. Push the 9-pin female connector into the 9-pin socket marked
'Computer' on the back plate of the controller (Cable B, Figure 5.3).
2. Push the 9-pin male connector into the serial port socket on the back
of the socket on the computer.
NOTE: You must configure the software for the appropriate communications port—refer to the
online help for instructions on how to do this.
Vous devez configurer le logiciel en fonction du port de transmissions utilisé—se référer à l'aide
fournie dans le logiciel.
Figure 5.3
Cable Connections
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Connecting Air and Water to the Rheometer
Refer to Figure 5.4 on the previous page for information on the location of the relevant connections in the
instructions below.
1. Connect a supply of cooling water the flow and return connections at the rear of the rheometer
2. Connect the air supply (from the air regulator assembly) to the 'air in' connection.
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Using Smart Swap™
The following sections explain how to attach/detach temperature modules using Smart Swap™. Note, however, that the installation and removal procedures are essentially the same for all modules.
The following modules are covered:
• Peltier plate
• Concentric cylinders
• Environmental Test Chamber (ETC).
Installing the Peltier Plate
1. Press the 'Release button' on the control panel
as seen in Figure 5.4. A continuous green light
indicates that the attachment can be fitted.
NOTE: The release state will only
stay active for 10 seconds.
Le dévérouillage restera seulement
actif pendant 10 secondes.
2. Fit the attachment as shown in Figure 5.5 below,
ensuring it is aligned correctly.
Figure 5.5
Fitting the Attachment
Figure 5.4
Press the Release Button
3. Connect the power and fluid cables. See Figure 5.6.
4. When the green status light goes out, the rheometer is ready for
use.
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Figure 5.6
Connecting Power and Fluid Cables
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Removing the Peltier Plate
1. Press the 'Release button' on the control panel
(see Figure 5.7). A flashing green light indicates
that the attachment can be unplugged.
2. Press the Release button again. A continuous
green light indicates that you can remove the
attachment.
3. Remove the attachment from the rheometer. See
Figure 5.8.
Figure 5.7
Releasing the Attachment
Figure 5.8
Removing the Peltier Plate
NOTE: The release state will stay active for 10 seconds and
then revert to locked.
Le dévérouillage restera actif pendant 10 secondes. A l'issue
de ces 10 secondes la plaque sera vérouillée
automatiquement.
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Setting Up the Concentric Cylinder System
The concentric cylinder system consists of a water jacket, an inner cylinder (the cup) and a rotor (or bob).
To set up the concentric cylinder system, follow these
steps:
1. Raise the rheometer head to the top most position.
2. Press the 'Release button' on the control panel as
seen in Figure 5.9. A continuous green light indicates
that the attachment can be fitted.
NOTE: The release state will only stay
active for 10 seconds.
Le dévérouillage restera actif pendant 10
secondes.
3. Fit the cylinder attachment, ensuring it is aligned
correctly.
Figure 5.9
Releasing the Attachment
Figure 5.10
Fitting the Cylinder Attachment
4. Connect the power and fluid cables as shown in
Figure 5.11 to the right.
5. When the green status light goes out, the lower
cup is correctly installed.
6. Lift the rheometer head and attach the correct
rotor (bob) to the air bearing.
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Figure 5.11
Connecting Fluid Cables
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7. Lower the rheometer head until the datum mark on the
shaft of the rotor is level with the top of the cup as
shown in Figure 5.12 to the right. You can now set up
the measuring geometry in the rheometer software and
set the gap explained in the online help.
Changing the Cup
If you need to change the size of the cup you are using,
follow these steps:
1. Undo the two screws on the cup. Turn and lift it out as
shown in the figure below.
2. Replace with the required cup size and twist into place.
Tighten the two screws by hand.
Figure 5.13
Changing the Cup
Figure 5.12
Lowering Rheometer Head
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Using the ETC
This section provides information on how to install and set up the Environmental Testing Chamber (ETC). For more information on the ETC, see the
Rheology Advantage online help.
1. Turn on the rheometer and move the rheometer head up to the maxi-
mum height. (Use the 'Head UP' button, located on the instrument
control panel.)
2. Fit the air-bearing clamp to the rheometer (see the start of this chapter).
3. Turn off the power to the rheometer control box.
4. Ensure that the two top screws (A and B in Figure 5.14) are fitted with
washers and are located in place—but make sure that they are almost
totally unscrewed (two turns in).
5. Open the ETC oven (see Figure 5.15) and then use the handles on the
oven doors to lift it onto the two top screws. Lightly tighten these
screws.
Figure 5.15
The ETC Open
6. Insert the final two screws (C and D in Figure 5.15).
7. Adjust the position of the ETC on the screws and then tighten all
four.
8. Check the adjustment and adjust if required by loosening the screws
and shifting the position of the ETC on the rheometer.
9. Connect the two cables on the ETC to the attachment connectors on
the rheometer as shown in Figure 5.16.
10. Open the ETC oven doors to gain access to the Smart Swap™
mounting.
Figure 5.14
Mounting Screws
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Figure 5.16
Connecting the Cables
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11. Press the 'Release button,' , on the control panel. A continuous
green light indicates that the attachment can be fitted.
NOTE: The release state will only stay active for 10
seconds.
Le dévérouillage restera actif pendant 10 secondes.
12. Fit the lower attachment, ensuring it is aligned correctly. See Figure
5.18 below.
13. Connect the cable
from the lower attachment to the rheometer as
seen in Figure 5.19.
Figure 5.17
ETC with Open Oven Doors
14. Close the oven and
ensure that no part of the
doors touch any part of
the lower fixture. Adjust
Figure 5.18
Fitting the Lower Attachment
the position of the ETC
again, if required.
15. Attach the upper geometry, again making sure that no parts
are touching the fixture, adjusting the ETC if necessary.
16. If you plan to use the liquid nitrogen option with the ETC, skip
the following steps and proceed to the next section for installation instructions.
17. Insert the shorting plug into the
Event A connection on the
rheometer as shown here.
Figure 5.19
Connecting the Cable from the Lower
Attachment to the Rheometer
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18. Connect the purge gas to the rheometer as seen
in Figure 5.20 to the right. If you have a suitable
supply of nitrogen gas (2 bar minimum pressure, nominal 10 liters per minute flow rate) it is
recommended that you connect the feed gases
to the ETC as shown in Figure 5.22. Otherwise,
connect as shown in Figure 5.21 below.
CAUTION: The reducing valve
is factory-set to 10 liters per
minute and should not be
adjusted.
La valve réductrice est réglée à
10 litres par minute et ne
devrait pas être modifiée.
Figure 5.20
Connecting the Purge Gas
Figure 5.21
ETC Connections Using Air as the Agitation Gas
Figure 5.22
ETC Connections Using Nitrogen as the Agitation Gas
Removal of the ETC is the reverse of the preceding steps. Note, however that you can leave the oven in place
when you wish to use the one of the Peltier systems.
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Installing the Low Temperature Accessory
In order to operate the ETC at temperatures below ambient and also to facilitate rapid cooling, the (optional) low
temperature accessory can be used. This works by supplying a controlled flow of liquid nitrogen/cold nitrogen
that is fed down the inside of the oven and evaporates off the wire wool.
Follow the installation procedure in the previous section up to step 15. Then use
the following additional steps to complete the installation (see Figure 5.24 and
Figure 5.25).
1. Connect the Event cable from the flow control assembly to the Event A connection on the rheometer.
2. Ensure that the cryogenic system has been installed as directed in the instructions supplied by the manufacturer.
3. Connect the flexible hose from the outlet of the cryogenic cooling system to the
'Liquid in' connection on the flow meter assembly as shown in Figure 5.23.
Connect the purge gas from the flow control assembly to the rheometer.
Figure 5.23
Connecting the Hose
4. Connect a gas feed to the 'Gas in' connector on the flow control assembly. If you have a supply of nitrogen
gas follow Figure 5.25, otherwise follow Figure 5.24.
5. Connect the cable from the 'Liq' connector on the flow assembly to the solenoid valve on the cryogenic
system.
6. Set a pressure of 15 to 20 PSI on the Dewar system.
7. Open the control valve approximately two full* turns.
8. Set a flow rate of 10 liters per minute (LPM) on the flow meter assembly.
* The exact setting depends upon the required operating conditions for the ETC as well as the type of cryogenic
cooling system used. Additional information on this setting can be found in "Operating Hints" later in this
chapter.
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Figure 5.24
ETC Connections with LN2
Figure 5.25
ETC Connections with Nitrogen
If the system has been set up according to the instructions, the rheometer should now be ready to use. However,
we recommend that you follow a few extra precautions, described on the next several pages.
• If you are planning to start your experiment at a high temperature, preheat the system by lowering the
head to the measurement gap and allowing upper and lower geometries to rise to the set temperature.
• When you use the cone and plate or parallel plate geometries, it is important to use the correct sample
volume. The Rheology Advantage™ software calculates the exact volume required based upon the gap
size and geometry diameter. If you know the density of the sample, you can weigh out the correct amount
of sample. If you underfill or overfill the gap, you can cause experimental errors in your data.
• When you use the parallel plates, make sure that the oven thermocouple is not touching the plates.
• When you use the parallel plates, if you find that the lower plate is difficult to remove, make sure that you
apply a twist to the lower mounting plate—do not apply any force to the ceramic part of the geometry.
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• Clean the plates immediately after your experiment with the appropriate solvent. If you are measuring
highly viscous materials, or materials that are likely to cure, unscrew the draw rod from the geometry
before you raise the head. Stubborn materials can sometimes be removed by heating the plates to a high
temperature. The sample will bake and then crumble apart. You can also remove the plates and soak them
in an appropriate solvent, or replace them with a fresh pair. It is good practice to always unscrew the
draw rod before raising the head. The two plates, together with the sample, can then be removed as a
sandwich unit.
• You can gently move the thermocouple (inside the oven) closer to the sample to increase performance;
however, you should avoid making any sharp bends in the thermocouple sheath. Repeatedly adjusting the
positioning may damage the thermocouple and should be avoided.
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Operating Hints
Although the response time of the temperature control system is rapid, many of the samples that are of interest
at high temperatures (e.g., bitumen, molten polymers, etc.) are very poor conductors of heat. Therefore, the
limiting factor in reaching the desired starting temperature is the time it takes for the heat to be conducted into
the sample and for the sample to reach thermal equilibrium. You can investigate a sample by carrying out an
experiment using no equilibrium time and doing a time sweep experiment (in oscillation mode). If you plot a
graph of how the properties of the sample vary with time, you can quickly establish the required equilibrium
time.
The tendency of polymers (which are measured while in their molten state) to oxidize can present an additional
complication. This problem is generally sample-dependent, but can be reduced by surrounding the sample with
an inert atmosphere. To do this, use nitrogen gas rather than air as the feed to the ETC. It also helps if you
optimize your test procedures to minimize the amount of time that the sample is held at high temperatures.
Make sure the upper geometry is in place and free to rotate when you perform procedure for mapping of the
bearing. For best results, perform the mapping procedure at ambient temperature and without purge gas
flowing. (Further information on the mapping procedure can be found in the Rheology Advantage Help™
system.)
Controlling Cooling
When you set the control valve on the liquid nitrogen unit, you must compromise between the rate of cooling
(which is improved by having a large flow rate) and the fineness of control (which is optimized when there is
minimal flow rate from the needle valve.) When only a small amount of cooling is required, the solenoid valve is
able to open and shut frequently. However, if a large surge of coolant occurred every time the solenoid valve
opened, the system temperature would oscillate on either side of the set point.
The setting of the needle valve is affected by the desired set-temperature:
• If cooling is needed at only a few degrees below ambient, then a very small opening is all that is necessary.
• If you operate at -100° C, then a correspondingly higher flow rate of nitrogen is required.
As a general rule, the correct needle valve setting for the desired temperature is one that results in the opening
and closing of the solenoid valve for more or less equal periods. Start with a setting of "open two complete
turns" and experiment to find the optimum position for your work experiment procedures.
WARNING: The electronic control box supplied with the ETC has no user serviceable
parts inside.
Le cadre de commande électronique fourni avec le four ne contient aucun
consommable.
Low Temperature System Maintenance
For maintenance instructions of the cryogenic pressure vessel, please refer to the instructions supplied with the
unit. If you purchased the Dewar flask from TA Instruments, the document is titled "Guide to good housekeeping, maintenance and periodic examination of cryogenic pressure vessels."
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General Operating Guidelines
To ensure that your temperature system operates efficiently and safely, follow these suggestions below.
Do
Ensure that all operators of this equipment have been correctly trained and are aware of the safety information
contained in this manual.
• Put this list (or a similar one) in a prominent place near the instrument.
• Read all instruction manuals supplied, as they contain useful operational hints and maintenance
information.
• Ensure that the gap is correctly set.
• When installing parallel plate geometries, carefully ensure that the thread is engaged squarely to avoid the
possibility of cross threading.
• Avoid any unnecessary movement of the liquid nitrogen carrying hoses when at low temperatures.
Excessive movement or strain could cause the hose to crack.
Do Not
• Leave the high temperature system switched on or the nitrogen tank tap open, when not in use.
• Attempt to remove a hot geometry without wearing safety gloves.
• Forcibly remove a geometry.
• Allow any object to obstruct the safety interlock sensors at the rear of the ETC housing.
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Keypad Functionality
The following table provides a list of each button found on the instrument keypad shown in the figure below.
Figure 5.26
AR 2000 Keypad
Feature Description
On/Off Indicator A continuous red light indicates that rheometer is receiving power.
Smart Swap Release Status
Off Attachment holder is locked.
Flashing green Power to attachment is removed (holder still locked.)
Continuous green Attachment holder is unlocked.
Head up Moves the rheometer head up while pressed.
Head down Moves the rheometer head down while pressed.
STOP Aborts the current activity on the rheometer, such as gap zeroing, running a
procedure etc.
Zero Gap Initiates an "auto-zero" of the gap using the currently installed measuring
geometry. This duplicates the functionality of the zero gap button in the instrument software.
To maximize gap zeroing time, you should position the geometry to within 5 mm
above the plate before pressing this button.
Release Activates the release mechanism for Smart Swap (see previous page for more
information).
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Levelling the Rheometer
Optimum performance depends upon the instrument being level and in a sturdy position to avoid the possibility of rocking. To check and see whether your instrument is level, simply place a bubble spirit level on the lower
temperature module plate.
If the instrument is
as necessary. Check the spirit level after each adjustment. Once you have the instrument levelled correctly,
press each corner of the instrument to check that all four feet are in contact with the laboratory bench. Any
movement caused by pressing should be rectified by adjusting the feet, and then rechecking the level of the plate.
If the spirit level is the circular type, it should be placed in the middle of the plate. If the spirit level is the bar
type, place it along a diameter of the plate. Check the level by placing it along another diameter of the plate at
90° to the first position.
not level, screw the adjustable feet (located at each corner of the instrument) either in or out,
Checking Your System
After installation has been completed, start the instrument to check to make sure everything is working and that
all parts of the system are communicating with each other. Use the following steps to check your system:
1. Turn on the air supply to the instrument.
2. Turn on the water supply to the instrument.
3. Remove the air-bearing clamp.
4. Turn on all electrical parts of the system (rheometer, PC, etc.). A system check will be initiated as shown by
the LCD on the electronics control box.
5. Start the rheology software.
6. Select the Instrument Status screen in the software.
7. If everything is installed correctly, the instrument will display continually updating figures.
8. Lower the head using the buttons in the software. If the installation is OK, the head will operate.
9. Input a temperature slightly different to that displayed. If the installation is OK, the temperature will
change to the new one you have just input.
10. Raise the head.
If all of these actions result in the correct response, you can be confident that you have installed the system
correctly and it is ready for use. If you have problems, please contact your local TA Instruments office or their
appointed agent.
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Calibrating the Rheometer
Strictly speaking, you cannot calibrate your rheometer yourself. You can check that the instrument is functioning properly by measuring the viscosity of a certified standard Newtonian oil. (Cannon S600 oil, which has a
nominal viscosity of 1.4 Pas at 25°C, or PTB 1000A, which has a nominal viscosity of 1 Pas at 20.0°C.) If you get
a greater than 4% error in the reading, there is a possibility that your rheometer needs some attention from a TA
Instruments Service Engineer.
Carry out the following experiment:
1. Attach a 60 mm 2° stainless steel cone to the rheometer. (This is the preferred geometry, if you do not have
one use the largest cone that you do have.)
2. Set the zero gap and measurement system gap in the usual way.
3. Carefully load the sample ensuring correct filling.
4. Carry out a 4-minute flow test, continuous ramp, controlled stress range 0 to 88.0 Pa at 20°C.
5. Determine the Newtonian viscosity. If this value is more than 4% different from the certified value, repeat
the experiment. If there is still an error, call your local TA Instruments office for advice.
There are several sources of operator error that can give erroneous answers. This does not necessarily mean that
your instrument is not working properly. These include errors in setting the gap, incorrect temperatures used,
or over- or under-filling of the gap. This calibration check needs to be carried out monthly.
Shut-Down Procedure
When you are ready to turn the instrument off, it is important that you follow the steps listed below in the
correct order.
1. Raise the head and remove the measuring geometry.
2. Exit the software package that you are currently running.
3. Turn off the rheometer and the computer.
4. Replace the air-bearing clamp.
5. Turn off the water supply to the instrument.
6. Turn off the air supply to the instrument.
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Cleaning the Filter Regulator Assembly
The air bearing requires a very clean supply of air regulated to a stable pressure of between 25 to 40 psi, dependent upon the air bearing. The filter regulator assembly is an important part of your rheometer system. It is
designed to meet the required standards of cleanliness (99.9999% of particles above 0.01 mm retained) and
regulation, given that the source of air is dry and pre-filtered.
The maximum inlet pressure is 147 psi (10 bar). The maximum pressure to the rheometer is 42 psi (3 bar).
The filter regulator assembly is shown schematically in Figure 5.27.
From air
supply
Filter bowls
containing
filter elements
To Rheometer
Pressure
Gauge
Figure 5.27
The Filter Regulator Assembly
If you use the filter regulator, you will need to check routinely (i.e., at least monthly) for any signs of contamination (i.e., water, oil or dirt) collecting in the filter bowls. If you see a build up of water, follow these steps:
1. Turn off the air supply and disconnect the assembly from the rheometer. Remember to put the airline plug
into the back of the rheometer.
2. Unscrew the filter bowl plug and dry the inside thoroughly.
3. Replace the plug and purge with air before reconnecting to the rheometer. The filter elements must also be
replaced when there is a visible buildup of dirt.
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Chapter 6
Measuring Systems
Overview
This chapter describes the geometries currently available from TA Instruments and provides guidelines to
choose the optimum geometry (or measuring system) for each application. A complete geometry catalog is
available which describes in detail each geometry and typical applications. Contact your local TA Instruments
office or their appointed agent for further details. Some theoretical considerations are given that will provide
guidance and help you maximize the use of the AR Rheometers.
TA Instruments offers a range of geometries. The geometries are divided into the following groups, each with a
range of sizes available:
• Cone and plate
• Parallel plate
• Concentric cylinders.
The following pages describe the types of geometries and provide details on how to attach the geometry to the
rheometer.
General Description
The measuring system is defined as those parts that are in direct contact with the sample or material.
A measuring system consists of two parts:
• One is the fixed member (or Stator), for example, the Peltier plate.
• The second part (the geometry) is attached to the driving motor spindle, where it is locked in position
using the draw rod. The draw rod is detachable and passes through the centre hole bored in the spindle.
The geometry constitutes the moving member of the system (the Rotor).
Geometry Materials
Geometries are usually constructed from stainless steel, aluminium, or acrylic (other materials can be supplied
upon request). The rotor should ideally be as light as possible to minimize inherent inertia effects. It should
also be chemically compatible with the test sample in order to avoid corrosion problems.
Stainless Steel
Stainless steel is relatively heavy, but it has a low coefficient of thermal expansion. It is compatible with most
test materials and is robust enough to withstand heavy use, even if you are a less experienced operator.
Aluminium
Aluminium has a higher thermal coefficient of expansion and is limited because of its chemical compatibility.
As it is lighter, inertial effects are not as great.
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Plastic
Engineering grade acrylic, polycarbonate, and rigid PVC are all suitable materials for geometry construction.
These are transparent so the visual behavior of the sample can be observed. Plastic geometries are also much
lighter than metallic geometries.
Acrylic and polycarbonate have less inertial problems as they are relatively light, but they have limited
chemical compatibility. You should not use plastic geometries above 40°C.
Cone and Plate
A schematic of a cone and plate system is shown below in Figure 6.1. It is important to know how to calculate
the stress and shear rate factors for each geometry before deciding on the geometry dimensions.
Figure 6.1
The Cone and Plate
Shear rate (s-1) = F
ω
where F = 1
α
tan
Shear stress (Pa) = F
where F
The standard diameters available are 20 mm, 40 mm and 60 mm with cone angles of 0.5° to 4° in 0.5° increments.
Cone and plate geometries are generally used for single-phase homogeneous samples or samples with submicron particles. Samples containing particulate matter are usually unsuitable for cone and plate geometries as
the particles will tend to migrate to the apex of the cone and will get jammed in the truncation area. Erroneous
data will result.
= 3
σ
2
π
R
M
σ
3
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The angles and truncation values of each cone are individually calibrated. A calibration certificate is available.
The serial number, angle and truncation are all inscribed on the stem of each cone.
Parallel Plate
The parallel plate system allows samples containing particles to be effectively measured. You can set the gap to
any distance, thereby eliminating the problems due to particles size. A good rule of thumb for particulate
materials is to set a gap size set at least 10 times greater than the largest particle size. For example, if the maximum particle size is 100 mm, you should set the gap to at 1000 mm.
The main disadvantage of a parallel plate system is that the stress is not uniform across the entire diameter.
However, the software compensates for this fact. The shear stress and shear rate factors given are with respect
to the rim.
A schematic of a parallel plate is shown in Figure 6.2.
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Figure 6.2
The Parallel Plate
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Concentric Cylinders
Concentric cylinder systems (or cup and
bob) are generally used for lower viscosity
samples that may not be held within the
gap of cone and plate or parallel plate
systems. (See later in this chapter for
information on setting up and using the
concentric cylinder systems.)
There are several different types including:
• Recessed end
• Conical end (DIN)
• Vane
• Double concentric.
See the following figures for examples of
concentric cylinder geometries.
The previous equations are also used for
the Vane system.
Figure 6.3
Recessed End
58
The shear stress factor is the same
as the geometry shown in Figure
6.3. The conical end aids penetration and even distribution of stiffer
samples.
Figure 6.4
Conical End
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The ratio R1:R2 = R3:R4. The shear
rate is then calculated as in Figure
6.3 using R3 and R4.
Figure 6.5
Double Concentric
Using the
Stress and Shear Rate Factors
The TA Instruments operating system software calculates the stress and shear rate factors, which are used by
the software in all subsequent calculations.
However, there may be occasions when you will need to enter these factors manually. If you do, follow the
sequence given below:
1. Multiply the angular velocity (ω) by the shear rate factor ( F ) to obtain the shear rate (s-1).
2. Multiply the angular displacement by the same factor to obtain the strain (dimensionless).
3. Multiply the torque (T) (µNm) by the shear stress factor ( F
) to obtain the shear stress (Pa).
σ
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Choosing the Best Geometry
When selecting the correct measuring geometry to use, it is important that you understand the following:
Exactly what type of experiment do you wish to carry out?
What is the sample behavior like—does the sample contain particles?
And probably most importantly, what is the real-life situation are you trying to recreate?
Sometimes the answers to all of the above questions are not known, but there are some basic guidelines that will
help you. However, it is also important to remember that you are measuring the bulk properties of the material
itself, and this should be independent of the type of geometry used (within reason!).
Cone and Plate/Parallel Plate Systems
The cone and plate and parallel plate systems both need small sample volumes, are easy to clean, have low
inertia, and can potentially achieve high shear rates. The additional advantage to using a cone and plate is that
the shear rate is uniform throughout the sample, and the parallel plate can accommodate large particles.
Generally, the cone and plate or parallel plate systems can be used for almost any sample. They are easy to set
up and use, making one of these systems the best choice
for optimum results. They are both available in different
sizes, therefore, it is important to understand how to
choose the system with the correct dimensions.
Angles
Cones are supplied by TA Instruments in any angle
from 0° to 4°, usually in 0.5° increments. The 4° cone is
the largest available, as the sample velocity profile
becomes unpredictable at higher angles and the mathematical expression of α ~ tan α is no longer valid.
The 4° cone is ideal for creep measurements, because a
longer displacement is required per unit strain.
The smaller the angle (or gap in a parallel plate system),
the higher the maximum shear rate obtainable.
Diameters
The smaller the diameter of a cone or parallel plate
system, the larger the shear stress factor. This means
that a small (e.g., 20 mm) diameter geometry should be
used with stiffer materials or medium to high viscosities. A 40 mm geometry is more versatile and it usually
allows the majority of medium viscosity materials to be
measured.
Figure 6.6
Choosing Geometry Angle and Diameter
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A large diameter geometry (e.g., 60 mm) is more sensitive to stress changes and is used to measure low viscosity
samples.
Be sure to load the sample correctly and be careful not to under or overfill the geometry. If this occurs, it would
effectively change the diameters of the cones and, hence, adversely affect the shear stress factors.
Figure 6.6 summarizes the information given above on the choice of angle (or gap) and diameter.
Material
Stainless steel is relatively heavy, has a low coefficient of thermal expansion, is compatible with most samples,
and is very robust.
Aluminium geometries are lighter than steel, but have a larger coefficient of thermal expansion. They will go to
temperatures greater than 40°C, but are still heavier than acrylic.
Acrylic geometries are very light and are, therefore, most suitable to use with low viscosity samples. However,
you should not use acrylic geometries above 40°C.
See the beginning of this chapter for more details on materials.
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Preventing Solvent Evaporation
If you are using samples that contain volatile solvents or are water-based, evaporation can cause problems
during measurements. TA Instruments has overcome this problem by using a solvent trap cover, which sits over
the geometry (but does not touch it).
Solvent trap version geometries have a well on top of the geometry. Place a small amount of the relevant solvent
into this well. The solvent trap cover has a lip that sits in the solvent, allowing the free space around the sample
to become saturated with the solvent vapor, which prevents evaporation.
A schematic of a solvent trap cover and geometry is shown in Figure 6.7 below.
Solvent trap
version
geometry
Solvent well
Solvent
vapor
saturated
free space
Figure 6.7
Solvent Trap Cover and Geometry
When using solvent trap systems it is generally advisable to run the inertia correction wizard (with solvent in
the trap, but no sample loaded).
Preventing Slippage at Sample/Geometry Interface
Some samples, such as hydrogels, contain a lot of water that can migrate to the surface of the sample. This can
cause a film layer to form between the bulk of the material and the geometry surface, causing slippage at this
interface. To alleviate this problem, use special crosshatched geometries, which, in effect, have the measuring
surface slightly roughened. (However, when you use these crosshatched geometries, there is a trade-off between
absolute accuracy and repeatability.)
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Removing the Air-Bearing Clamp
You should never remove the air-bearing clamp
until the air supply is connected and switched
on.
Once the air supply is switched on, and you can
hear the air through the rheometer, the clamp can
be safely removed.
To remove the clamp, firmly hold the clamp and
unscrew the draw rod by turning it counterclockwise (anticlockwise).
Removing the Air Bearing Clamp
CAUTION: Always hold
the clamp and turn the
knob - never the other
way round.
Toujours tenir la géométrie et tourner la molette - jamais le contraire.
Next, slide the bearing lock away and ensure that the
bearing is free to rotate.
Figure 6.8
The clamp is replaced in exactly the same way. The air
must not be switched off until the clamp is in place.
If your instrument does not have a bearing lock, then
ignore this step. This mechanical lock has been
removed from current production unit as the software
Bearing Lock implemented with the Mobius Drive
provides the same function without the risk of leaving
it in place at the start of a measurement.
Figure 6.9
Slide Lock Away
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Attaching a Geometry
This procedure is carried out using the same
technique as described for the air-bearing
clamp:
1. Switch on the air and remove the airbearing clamp by turning the draw rod
counterclockwise (anticlockwise).
2. Push the geometry up the drive shaft and
hold it while placing the draw rod in the
screw thread of the geometry.
3. Screw the draw rod upwards (clockwise).
It should be screwed finger tight, but not
forced.
To remove the geometry, use the reverse
process.
Clockwise Counterclockwise
(Anticlockwise)
Figure 6.10
Attaching/Removing A Geometry
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Ensuring that the Sample is Loaded Correctly
Ensuring that the sample is loaded correctly and the gap is properly filled is probably one of the most important
points to consider in any rheological experiment.
You will find that you will become quite adept at
judging the right amount of sample to use, depending upon the geometry diameter and gap
size. You can either calculate the exact volume or
weight of sample needed. However, care must be
taken if you intend to use a pipette or syringe to
deliver the correct amount. Samples that are
delicately structured will be adversely affected by
the high shear rate regime encountered in syringes
or pipettes. If the gap is not filled correctly, there
are certain types of errors that can occur. The
magnitude of the errors will be entirely sample
dependent, but generally over filling is less of a
problem than under filling. Such errors are called
edge effects. Figure 6.11 shows the different types
of filling encountered.
• If the gap is overfilled, some of the excess
sample may migrate to sit on top of the
geometry. If, however, the sample is of low
viscosity, this is not likely to happen and the errors are reduced.
• If the gap is underfilled, you are effectively altering the diameter of the geometry. This will inevitably
introduce large errors and you should definitely avoid this situation.
Loading the sample correctly is a skill that is learned with time. It may help you to spend some time initially
simply loading and reloading a sample. The correct loading is vital to accurate and meaningful results.
Figure 6.11
Loading the Sample
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Chapter 7
Using the Upper Heated Plate
Introduction to the Upper Heated Plate
At the standard AR 2000 Smart Swap™ Peltier plate's temperature range extremes, a temperature gradient may
be introduced across the sample, the significance of which will depend on the sample’s thermomechanical
properties. Although this gradient can be reduced by the use of an upper geometry containing a thermal break,
it can only be effectively eliminated if the Peltier plate and upper geometry are constrained to the same temperature. The Upper Heated Plate (or UHP) has been developed to allow this and is used in conjunction with the
standard Smart Swap™ Peltier plate.
The Upper Heated Plate consists of
two main components:
• A fixture that attaches to the
rheometer head. This fixture
contains electrical heating
elements and a coolant channel.
• An upper geometry holder that
attaches to the rheometer rotating
shaft. The geometry holder
contains a heat spreader.
There is no physical contact between
the two components (see Figure 7.1).
Heating of the Upper Heated Plate is
through the electrical elements.
Cooling is provided by vortex air, water, or other fluid carried in the coolant channel.
Control of the water flow is through a 3-way solenoid valve contained in a Cooling Control Unit (CCU) placed
upstream of the Upper Heated Plate. The CCU is also connected to an air supply, allowing purge air to displace
water from the coolant channel during heating or at elevated temperatures. If vortex air or fluids other than
water are used as coolants, purge air is not required, and the CCU is replaced by a 2-way solenoid.
A Pt100 probe placed within the Upper Heated Plate heat spreader reads the temperature of the Upper Heated
Plate. The offset between the read temperature and that of the upper geometry plate is obtained by prior calibration.
An inert gas atmosphere can be produced using the inert gas inlet located between the inlet and outlet coolant
ports on the Upper Heated Plate. The inert gas jets are located on the underside of the heating element cover. A
protective sample cover and an instrument air bearing clamp are also provided.
Exploded View of the UHP and Upper Geometry Holder
Figure 7.1
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Attaching the Upper Heated Plate to the AR 2000
Follow the steps below to attach the Upper Heated Plate to the AR 2000 rheometer head.
1. Ensure that air at the correct pressure is supplied to the air-bearing, and remove the bearing cap. Turn on
the rheometer and raise the head to the maximum (use the Head UP button located on the instrument
control panel).
2. Attach the Upper Heated Plate fixture to the mounting ring on the underside of the instrument head, using
the three captive screws provided. Note that the power cable should project to the right of the instrument
when viewed from the front, with the ports for the coolant and inert gas to the left (see Figure 7.2).
Mounting Ring
Coolant Ports
The Upper Heated Plate Shown Mounted on an AR 2000 Rheometer
3. Disconnect the Peltier plate cable
from the Smart Swap™ socket,
using the “Release” button on the
instrument control panel.
Power Cable
Heating Element Cover
Upper Geometry
Peltier Plate
Figure 7.2
Connector to
Smart Swap™
Socket
4. Connect the Peltier plate and
Upper Heated Plate cables to the
left and right sockets on the Smart
Swap™ Upper Heated Plate
adaptor respectively (see Figure
7.3 to the right).
68
Peltier Connector
UHP Connector
Figure 7.3
The Smart Swap™ UHP Adaptor
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5. Connect the Upper Heated Plate adaptor
to the Smart Swap™ socket (see Figure 7.4
to the right).
6. To return the temperature control to
Peltier plate only, remove the adaptor
from the Smart Swap™ socket using the
“Release” button on the instrument
control panel. Remove the Peltier connector from the adaptor and plug the connector directly into the Smart Swap™ socket.
WARNING: Do not remove
the heating element
cover.
ATTENTION: N’enlevez
pas la couverture
d’élément de chauffe.
Figure 7.4
Connection of the UHP Adaptor to the Smart Swap™ Socket
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Installing the (Optional) Vortex Air Cooler
Follow the steps below to attach and connect the vortex air cooler to the AR 2000. Refer to the figures as needed.
1. Use the two screws provided to mount the vortex air
cooler bracket to the rear of the AR 2000 casting as
shown in Figure 7.5 to the right.
2. Clip the vortex air cooler into the spring clips with the
brass muffler extending upward as shown in Figure 7.6
below.
Exhaust
Vent
(STEP 6)
Muffler
Vortex Tube
Mounting
Screws
(STEP 1)
Exhaust Air
From UHP
(STEP 5)
Black Insulated Tube
(STEP 4)
Figure 7.6
Attaching the Vortex Air Cooler
3. Remove the metal push-fit connector from
the inlet port on the UHP and fit the
Swagelok adapter supplied in the kit. See
Figure 7.7 to the right. (Note that once this
has been fitted, it cannot be removed.
Returning to the push-fit connector will
require the supplied adapter.)
White
Tubing
(STEPS
7&8)
Air Inlet
From
2-Way
Valve
Cold Air
Oultet to
UHP
Swagelok
Adapter
(STEP 3)
White Tubing
(STEP 5)
Insulated
Tube
(STEP 4)
Figure 7.5
Mounting the Bracket
Figure 7.7
UHP Swagelok Adapter
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4. Connect the black insulated tube between the lower (vertical) outlet of the vortex air cooler and the Swagelok
fitting on the UHP inlet, and insulate the exposed metal connections.
5. Cut 800 mm of the white 6-mm O.D. tubing. Connect this tubing between the Upper Heated Plate outlet and
the lower bulkhead fitting on the vortex air cooler bracket.
6. Cut 150 mm of white 6-mm O.D. tubing and connect one end to the upper bulkhead fitting on the vortex air
cooler bracket. The other end is left open to vent to the atmosphere.
7. Connect white 6-mm O.D. tubing between the outlet of the two-way valve and the middle (horizontal) inlet
of the vortex air cooler.
8. Connect the opposite end of the white 6-mm O.D. tubing used in step 7 to a source of dry compressed air (80
to 100 psi, –30°C dew point or better). An 8-mm "Y"-piece and 8-mm to 6-mm reducer are supplied to break
into the rheometer air line before the filter regulator.
9. Connect the event socket on the valve bracket to the EVENT B socket on the rear of the AR 2000 rheometer
using the cable provided.
Table 7.1
Minimum Temperature Maximum Temperature
Vortex Air Cooler –5 °C 150 °C
NOTE: If you find a reduction in the expected cooling performance, check that there is exhaust
air flowing from the white 8-mm O.D. tubing. If there is limited or no air flow, this is an indication
that the cold end of the vortex tube is blocked with ice, formed by condensing moisture in the
air supply. The tube can be taken apart and ice removed, but the only long-term solution is to
supply drier air.
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Configurations for the Cooling Water
The minimum temperature and the cooling rate attainable on the Upper Heated Plate will depend on the
temperature, flow rate and heat capacity of the circulating fluid. In general, provided that the flow rate is
adequate, the minimum temperature will be about 5°C above that of the circulating fluid at the inlet, although
this will depend on the ambient conditions. The standard configuration is with water as the circulating fluid,
in which case mains water or a general laboratory circulator can be used.
It is recommended that separate sources should be used for the cooling water supplied to the Peltier plate and
the Upper Heated Plate, as the pulsing of the cooling water can influence the instrument normal force reading.
However, the same supply may be used for both units, provided that sufficient pressure is available to ensure
adequate flow through both (for example from an FP50-MS fluid circulator available from Julabo GmbH,
www.julabo.com; mains water supply is also normally suitable). Note that if a single supply is used, the Peltier
and Upper Heated Plate should always be connected in parallel, never in series. Some possible configurations
are shown below.
Important: For efficient operation, the Peltier plate and Upper Heated Plate should be connected in parallel, NOT in series, if the same water supply is used for both.
Important: Pour une opération efficace, le plan de Peltier et l’Upper Heated Plate devraient
être reliés en parallèle, PAS en série, si la même source en eau est employé pour tous les
deux.
Air Inlet
Drain
Mains Water Flow
Air Inlet
Circulator
Water Flow
Non-Return
Valve
"Y"
Piece
Figure 7.8
Cooling Water Configuration 1
Mains Water Supplying Both Peltier and Upper Heated Plate
Reducer
"Y"
Piece
"Y"
Piece
Figure 7.9
Cooling Water Configuration 2
Fluid Circulator Supplying Both Peltier and Upper Heated Plate
Drain
Return
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Air Inlet
Mains Water Flow
Drain
Non-Return
Valve
Circulator
Water Flow
Return
Figure 7.10
Cooling Water Configuration 3
Fluid Circulator Supplying Peltier, Mains Water Supplying Upper Heated Plate
Alternative configurations, not shown here, are for the Upper Heated Plate and Peltier to be supplied by separate fluid circulators, and for the Upper Heated Plate to be supplied by a fluid circulator, the Peltier by mains
water. The non-return valve is not required for either of these configurations.
Connecting the Cooling Control Unit
This unit may be free standing, or wall mounted using the clearance holes on top of the unit (see Figure 7.11 to
the right below).
1. Connect the air supply to the GAS IN port on the CCU
using the 8-mm outer diameter tubing (white). If it is
necessary to split the air line to provide a source for
both the instrument air bearing and the CCU, this
should be done upstream of the instrument filter
regulator system.
2. Connect the water supply to the LIQUID IN port on the
CCU using the 6-mm outer diameter tubing (blue). If
mains water is used as the supply, then the non-return
valve (see Figure 7.9 below) should be placed in the line
upstream of the CCU.
Water IN
Water
OUT
Figure 7.12
Non-Return Valve
(For use with mains water supply only.
Note the direction of flow through the valve.)
AR 2000 Operator's Manual
Figure 7.11
The Cooling Control Unit
Important: Note the direction of flow through this
valve.
Important: Notez la direction d’écoulement à
travers de la valve.
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3. Connect the GAS /
LIQUID outlet port on
the CCU to the Coolant
Inlet port on the Upper
Heated Plate using the
4-mm outer diameter
Coolant Inlet Port
tubing (blue) and the 4mm to 6-mm adaptor
provided.
Inert Gas Port
4. Connect the Coolant
Outlet port on the Upper
Heated Plate to drain, if
Coolant Outlet Port
mains water is the
supply, or to return, if a
fluid circulator is used.
Use the 4-mm outer
diameter tubing (blue)
Coolant and Inert Gas Connections for the UHP
Figure 7.13
for this port. A 4-mm to
6-mm adaptor and 6-mm "Y" piece are provided for the connection to the fluid circulator.
5. Connect the EVENT socket on the CCU to the EVENT B socket on the rear of the AR 2000 Rheometer, using
the cable provided.
6. Set the purge air flow rate to 1 Liter per minute (L/min). Note that the reading is taken from the center of the
float. To set the flow rate, it may be necessary to raise the temperature of the Upper Heated Plate using
Rheology Advantage™ software, to ensure continuous air flow.
Using Circulating Fluids Other Than Water
For low temperatures, circulating fluids other than water must be used. These should be fluids of the silicone
type, as recommended by the supplier of the fluid circulator. A separate kit is available for use with these fluids.
WARNING: Flammable fluids such as ethanol or mineral oils should NOT be used with
the Upper Heated Plate. Circulating fluids should NOT be used outside the ranges
given by the supplier.
ATTENTION: Des fluides inflammables tels que l’éthanol ou les huiles minérales ne
devraient pas être employés avec l’Upper Heated Plate. Des fluides de circulation ne
devraient pas être employés en dehors des gammes données par le fournisseur.
Silicone fluids are usually higher in viscosity than water, and the required flow rates cannot be achieved with
the standard CCU described above. The special low temperature kit should replace this. As when water is used
as the circulating fluid, it is suggested that separate sources should be used for the cooling fluid supplied to the
Peltier plate and the Upper Heated Plate. Then water may be used for the Peltier, and a silicone fluid for the
Upper Heated Plate, for example. However, the same supply may be used for both units, provided that sufficient
pressure is available to ensure adequate flow through both. Note that if a single supply is used, the Peltier and
Upper Heated Plate should always be connected in parallel, never in series.
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1. Connect the flow port on the fluid circulator to the inlet of the 2-way valve using the 6-mm outer diameter
(blue) tubing provided.
2. Connect the outlet from the valve to the Upper Heated Plate inlet, and the outlet from the Upper Heated
Plate to the circulator return port using the 6-mm outer diameter tubing (blue). Note that when silicone
fluids are used as coolants, the air purge on the Upper Heated Plate is not required.
3. Connect the EVENT socket on the valve bracket to the EVENT B socket on the rear of the AR 2000 rheometer,
using the cable provided.
Table 7.2 shows minimum and maximum temperatures for the Upper Heated Plate, using circulating fluids
available from Julabo GmbH,
www.julabo.com, with an FP50-MS fluid circulator supplied by the same com-
pany.
Table 7.2
Circulating Fluid Minimum Temperature (°C) Maximum Temperature (°C)
Water 5 150
Thermal HY -30 55
Thermal H5S -20 105
Thermal H10S -10 150
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Connecting and Disconnecting the Geometry Holder
WARNING: The Upper Heated Plate fixture, upper geometry holder, and the upper
geometry, may be hot. Ensure that these components are cool before attempting to
remove or replace the upper geometry holder.
ATTENTION: Le montage d’Upper Heated Plate, le support supérieur de la géométrie
et la géométrie supérieure, peuvent être chauds. Assurez-vous que ces composants
sont froid avant d’essayer d’enlever ou remplacer le support de la géométrie
supérieure.
Connecting the Geometry and Holder
To connect the upper geometry and holder follow these steps:
1. Raise the instrument head fully, using either the Rheology
Advantage™ software or the Head UP button located on
the instrument control panel.
2. Attach the geometry to the holder, using the attaching tool
provided, if necessary. (This tool cannot be used with the
40-mm diameter geometry, which can attached to the
holder by hand.)
3. When the geometry is in place, carefully insert and position the holder within the Upper Heated Plate, and connect
to the instrument shaft by rotating the drawrod. For Upper
Heated Plate geometries, a backoff distance of 120,000 µm is recommended.
4. Use 1.448 x 10
-3
rad/Nm for the geometry compliance, unless other information is available.
Heat Spreader
25 mm Geometry
Figure 7.14
Upper Geometry Holder
(Shows the cylindrical heat spreader with
a 25 mm diameter geometry in place.)
Removing the Geometry and Holder
To remove the upper geometry and holder from the AR 2000 rheometer follow these steps:
1. Raise the instrument head fully, using either the Rheology Advantage™ software or the Head UP button
located on the instrument control panel. Grasp the holder firmly, and unscrew from the instrument shaft by
rotating the drawrod.
2. Lower the geometry holder carefully until it is clear of the Upper Heated Plate.
3. When the geometry holder is free of the instrument, the geometry can be removed from the holder using the
geometry attaching tool provided, if necessary.
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Configuring the Upper Heated Plate
The temperature of the upper Upper
Heated Plate is controlled through the
instrument firmware. For the best performance the control algorithm requires
accurate information concerning the
thermal properties of the Upper Heated
Plate and the cooling fluid. In the Rheology Advantage control module, under the
Options menu click Instrument and then
the Temperature tab. The window box
shown in the figure to the right will
appear.
A list of the features are described as
follows:
• Cooling Temperature: The
temperature of the circulating water,
measured at the inlet: should be
entered manually. For the vortex air
cooler, use the value given in Table
7.3
Figure 7.15
• Cooling range: This is inversely
proportional to the flow rate. For the
vortex air cooler, use the value in Table 7.3. Typical values are given in the table below.
UHP Configuration Window
Table 7.3
Feed Temperature Flow Rate Range
Mains Tap Water 15 °C 0.75 Liter min
Fluid Circulator 5 °C 0.25 Liter min
-1
-1
5 °C
15 °C
Vortex Air Cooler 15 °C -- 100 °C
• Thermal mass: The energy required to raise the temperature of the upper platen. It is suggested that the
value of 65 J/°C, obtained by TA Instruments, be used unless other information is available.
• Gradient calibration span: Arrived at by calibration (see below) although a manual entry may be made.
• Gradient calibration offset: Arrived at by calibration (see below) although a manual entry may be made.
• Modeling enabled: If this box is checked, the temperature of the upper platen will be matched as closely
as possible to that of the Peltier plate during heating or cooling. This means that the heating or cooling rate
of both platens is constrained to that of the slower of the two (usually the upper platen). To remove this
constraint, allowing the faster platen to change temperature more rapidly than the slower, uncheck this
box.
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Calibration of the Upper Heated Plate
The temperature of the Upper Heated Plate is read from a probe positioned within the Upper Heated Plate heat
spreader as close to the upper geometry as possible, although not in physical contact with it. The temperature of
the Peltier plate is read from a probe positioned in thermal contact with the plate as close to the surface as
possible. The temperature reported by Rheology Advantage is that of the Peltier probe. For best performance the
Upper Heated Plate probe should be calibrated to the temperature of the upper geometry plate.
NOTE: Calibration should be performed on installation of the Upper Heated Plate, and at least
annually thereafter. The calibration routine may take several hours, and it is more efficient to
perform a single calibration with more points, rather than several calibrations with fewer points
NOTE: Le calibrage devrait être effectué sur l’installation de l’Upper Heated Plate, et au moins
annuellement ensuite. La routine de calibrage peut prendre plusieurs heures, et il est plus
efficace d’effectuer un calibrage simple avec plus de points, plutôt que plusieurs calibrages
avec peu de points.
During the automatic calibration routine a heat flow sensor is used to determine the temperature gradient
between the Peltier plate and the upper geometry. The gradient is reduced to within preset tolerances by adjusting the temperature of the Upper Heated Plate while the temperature of the Peltier plate is held constant. After
each adjustment a user-defined stability criterion is applied and, once temperature stability is achieved, comparison is made with the gradient tolerance. When the gradient tolerance condition is satisfied the temperature
value is accepted.
The procedure is repeated for a number of points over a range set by the user. When the calibration routine is
complete the temperature values for the upper
geometry determined by the calibration are compared
with those reported by the Upper Heated Plate probe
to obtain the appropriate offset and span values.
1. Under the Options menu click Instrument and
then the Temperature tab. The window, shown
in Figure 7.15 on the previous page, will be
displayed.
2. Ensure that the Cooling temperature and Cool-
ing range boxes contain the appropriate values.
3. Click Calibrate. The Calibrate Zero Heat Flow
window, shown in Figure 7.16 shown to the
right, will be displayed.
The parameters shown on the window are
described as follows:
• Start Temperature: Temperature at which
calibration is to begin.
UHP Calibrate Zero Heat Flow Window
• End Temperature: Temperature at which
calibration is to end.
Figure 7.16
• Number of Points: Number of temperature points, which will be at equal intervals.
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• Initial Equilibration Time: Time at each set temperature, before readings are taken.
• Adjust Equilibration Time: Time after each adjustment to the Upper Heated Plate temperature, before
readings are taken.
• Average Time: Time after each adjustment, over which successive temperature readings are averaged
to provide a data point.
• Average Stable Tolerance: Range within
which two successive data points must fall
for the temperature to be accepted as stable.
• Gradient Zero Tolerance: Once stability is
achieved, the last data point is compared
with the set temperature. If the difference is
not more than the gradient zero tolerance, the
set temperature is accepted as the temperature value. If the difference is greater than the
gradient zero tolerance, a further adjustment
is made to the Upper Heated Plate temperature.
• Gradient Scale Factor: It is suggested that
the default value of 1.5 should be used unless
other information is available.
4. Click Next. A window similar to that shown in
Figure 7.14 is displayed. Follow the instructions
given. The Upper Heated Plate calibration box
and zero value plug are shown in Figure 7.18
below.
Upper Heated Plate Calibration Box (Left) and Zero Value Plug (Right)
Figure 7.17
Zero Value Determination Instructions
Figure 7.18
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5. When the zero value calibration has been completed
a window, similar to that shown in Figure 7.16, will be
displayed. Follow the instructions given. The zero heat
flow sensor is shown connected to the calibration box in
Figure 7.20 below.
Zero Heat Flow Sensor Connected to
Calibration Box (Note the T on the
Figure 7.19
upperside of the sensor.)
UHP Calibration Instructions
6. Use the instrument Head UP and Head DOWN buttons to position the heat
flow sensor between the Peltier plate and the geometry as shown in Figure
7.21.
7. Click Next to begin
calibrating as instructed
(see Figure 7.19, above
left). When the calibration is complete the
results will be displayed
as shown in Figure 7.22
(to the left).
Figure 7.20
The graph shows the
temperature difference
between the set temperature and the temperature
read by the Upper
Heated Plate heat
spreader probe, plotted
Positioning the Heat Flow
Figure 7.21
Sensor
against set temperature.
The Gradient calibration span is the slope of the best-
fit straight line through the data, and the Gradient
calibration offset is the intercept.
Figure 7.22
Results of UHP Calibration
8. To accept the values click Next. The instrument
firmware will automatically be updated with these
values.
9. When the calibration is finished, raise the instrument head, and remove the calibration sensor. Remove the
connector from the electronics box.
NOTE: For safety reasons the temperature control is set to idle at the end of the calibration
routine, although the final temperature will still be displayed as the set temperature.
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Clamping the Air Bearing
An air-bearing clamp is provided for use with the Upper
Heated Plate. Never attach or remove the clamp unless
the air supply is connected and switched on.
To attach the clamp
1. Remove the geometry holder from the instrument
shaft, and remove the geometry from the holder (see
Figure 7.23).
2. Replace the geometry holder
3. Push the clamp up onto the drawrod and attach it by
turning the drawrod counterclockwise
(anticlockwise).
To remove the clamp hold it firmly and release it by
turning the drawrod clockwise.
Figure 7.23
Air-Bearing Clamp
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Using an Inert Gas Atmosphere
Many samples experience oxidation at elevated temperatures—an atmoshere of inert gas such as nitrogen or
argon can be used to prevent this. The gas supply should be regulated to less than 40 psi (2.8 bar) before
connection to the Upper Heated Plate. A gas flow meter (not supplied) should be used to set the gas flow rate.
1. Connect the gas supply to the inlet port on the gas flow meter.
2. Connect the outlet port on the flow meter to the inert gas inlet port on the Upper Heated Plate using 4-mm
outer diameter tubing (white) and the connector provided.
3. Set the inert gas flow rate at 1 Liter per minute (L/min). If the gas flow rate is set too high, temperature
control of the Upper Heated Plate may be affected.
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Using the Sample Cover
Some samples are affected by drafts and general air flow, which can cause drying at the sample edge. To avoid
this, a protective sample cover is provided. The cover should be placed in the up position during sample
loading and trimming: the cover is held in this position by a bayonet fitting that attaches over the coolant
connectors. The cover should be used in the down position during the experimental run.
Figure 7.24
Sample Cover
Up Position (Left ) and Down Position (Right)
WARNING: The sample cover may be hot. Ensure that it is cool before attempting to
raise or remove it.
ATTENTION: Le couvercle échantillon peut être chaud. Assurez-vous qu’il est froid
avant d’essayer de l’enlever.
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Chapter 8
The Pressure Cell
Overview
WARNING: TA Instruments' Pressure Cell is designed for use at temperatures up to 150°C
and pressures up to 138 bar (2000 psi) . At all times during the use of the cell, wear safe ty
glasses and clothing that afford adequate protection against the sa mple under test, and
the temperature and pressure used. At other than ambient temperature, the outer
surfaces of the cell may become very ho t or cold. When operating at these temperature s,
wear gloves that afford adequate protection against the surface temperature of the
pressure cell and its fittings.
The Pressure Cell is used with the standard concentric cylinder, Peltier-controlled, heating jacket. A copper
sheath is fitted to the cell to ensure good heat transmission between the jacket and the cell.
The Pressure Cell may be used either in self-pressuring mode, in which the pressure is produced by the volatility
of the sample, or in external pressurization mode, with an applied pressure of up to 138 bar (2000 psi). In this
chapter, the pressure cell assembly and operation for both modes are described.
NOTE: For external pressurization, the user of the cell is required to provide a high-pressure
source, and suitable pressure-rated connections to a 1/8-inch or 1/4-inch NPT female fitting.
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Specifications
Operating Specifications
The specifications for the standard pressure cell concentric cylinders are:
Stator inner radius: 14.00 mm
Rotor outer radius: 13.00 mm
Cylinder immersed height: 44.00 mm
Gap: 3500 µm (recommended)
Backoff distance: 3500 µm
Geometry inertia: 92.00 µN.m.s2 (approximate)
Sample volume: 9.5 ± 0.5 ml
Temperature range: -10 to 150°C
Maximum applied pressure: 138 bar (2000 psi)
Maximum pressure (self-pressurizing): 5 bar (72.5 psi)
Torque range about 100 µN.m to 0.2 N.m
Maximum angular velocity: 50 rad/s
Seal construction: DuPont Kalrez®
Safety Specifications
Over pressure rupture disk: 172 bar (2500 psi)
Hydraulically tested to: 414 bar (6000 psi)
Operational Limits
CAUTION: To prevent sample entering the upper part of the cell and contaminating the
bearings, the cell should not be used above the limits give n below. Exceeding these limits
may also cause mechanical damage to the cell.
• Maximum Angular Velocity: 50 rad/s
• Maximum Sample Viscosity: The geometry should not be forced into the sample. Light hand pressure
should be all that is required.
• Maximum Frequency: 50 Hz (314 rad/s)
NOTE: The quality of data obtained using the pressure cell cannot be expected to match that
obtained when conventional measuring systems are used with the rheometer. Some of the
normal calibration routines are not relevant to, or cannot be used with the Pressure Cell.
Alternative calibration routines are described in this chapter.
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Pressure Cell Components
Magnet
Cup
Peltier
Heating
Jacket
Manifold
Assembly
Figure 8.2
Pressure Cell on AR Rheometer
Cup
The Pressure Cell consists of four main
component assemblies. These components include the pressure cell cup, the
concentric cylinder rotor, the magnet
assembly, and the pressure manifold.
Figure 8.1 shows a schematic cross section of the pressure cell cup, rotor, and
magnet assemblies, and Figure 8.2
shows a fully configured Pressure Cell
installed on an AR Rheometer. The
following section will discuss these
four components individually.
Magnet
Assembly
Rotor
Assembly
Cover
Kalrez
Sapphire
Bearings
Kalrez® Seal
Gauge Port
TM
Seal
Retaining Plate
4-Pole
Magnet
Thumbscrew
4-Pole
Magnet
Locking Nut
Rotor
Inlet Port
AR 2000 Operator’s Manual
Figure 8.1
Cross Section Schematic
The Pressure Cell is shown assembled on the AR rheometer, with the instrument head in the DOWN position, in
Figure 8.2 to the left.
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The Pressure Cell Cup
Figure 8.3
Pressure Cell Cup with Rotor Assembly
Figure 8.4
Pressure Gauge Port
(Gauge and Valve Shown)
The Pressure Cell Cup contains
the sample fluid. It is inserted into
the Peltier jacket, which mounts
on the rheometer using the Smart
TM
Swap
connection. A copper
sheath ensures good heat transmission between the jacket and the
cup. There are three ports on the
cup, which are identified by
engraved labels.
NOTE: When
installing NPT fittings use
Teflon® thread
sealing tape.
CAUTION: Do not attempt to attach or detach any fittings to or from the cell while it is
mounted on the rheometer. Doing so can cause damage to the instrument.
Rupture Disk
Assembly in the
SafetyRelief
Port
Pressure Gauge
in the Pressure
Gauge Port
Rotor
Assembly
Cap
Snubber and
Compression
Fitting in the
Inlet Port
The Inlet Port
The Inlet Port, which is used in the external pressurization mode, is where the compressed gas is introduced
to the cup. A pressure manifold is supplied that attaches to the inlet port using a compression connector. A
pressure snubber is fitted between the port and the high-pressure line to slow the pressure build and prevent
sample from entering the line.
The Pressure Gauge Port
This port is fitted with a pressure gauge which indicates the pressure within the cell, and a relief valve. This
valve is only intended to be used when the pressure
from the cell cannot be relieved in the usual way (see
"Pressurizing and Depressurizing the Cell," found later
in this chapter). You will need a 5/8-inch open or boxend wrench to hold the valve body and a 7/16-inch
wrench to open the valve.
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Safety Relief Port
The Safety Relief Port is equipped with a rupture disk assembly that is designed to relieve excessive cup pressure.
At excessive internal pressure, the rupture disk breaks and propels the internal atmosphere out of the cup.
WARNING: Do not operate the pressure cell without the safety relief fitting in place. Do
not remove the rupture disc from the safety valve fitting, as this may cause the pressure
cell to crack during an overpressure condition, resulting in damage and personal injury.
The rupture disc should only be replaced by a qualified TA Instruments Service Representative.
CAUTION: You MUST install the Safety Relief Port with the Rupture Disk such th at it is
pointed to rear of the AR-G2 and away from t he operator. This will prevent sample material
from being ejected toward the operator in the event of an over-pressure situation.
Rotor Assembly
The rotor assembly contains the Concentric Cylinder rotor, which is mounted on a shaft that is radially supported
by two sapphire bearings located under the rotor assembly cap . Also atta ched to th e shaft is a f our- pole magne t.
The rotor assembly installs into the cup using a threaded mount, and seals with a Kalrez® seal. A second Kalrez
seal is seated between the cap and the thumbscrew.
4-Pole
Magnet
Locking
Nut
Rotor
Thumbscrew
Cap
Kalrez
Seal
Figure 8.5
Pressure Cell Rotor Assembly with Cap Off (Left) and On (Right)
CAUTION: Prior to use, ensure that the two Kalrez seals are installed and are in good
condition. Replace, if damaged, with seals provided by TA Instruments only.
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Magnet Assembly
Figure 8.6
Magnet Assembly with
Cover
Reference
Mark
Figure 8.7
Magnet Assembly with AR 2000/
AR 2000ex Adapter Insert
Adapter
Insert
(Used with
AR 2000/AR 2000ex.)
(Remove for AR-G2.)
The magnet assembly attaches to the rheometer's rotating spindle,
and then lowers over the rotor assembly. The spindle collar of the
magnet assembly includes an insert adapter. The adapter insert
should remain in the collar for use with AR2000 or AR2000ex
rheometers. If using the pressure cell with an AR-G2 rheometer,
take the adapter insert out of the spindle collar by removing the
two Phillips (or cross head) screws extending for the outer surface
of the spindle collar. See the figure below. Like the rotor assembly,
the magnet assembly contains a 4-pole magnet. When the spindle
and magnet assembly are rotated, the attraction between the two
4-pole magnets produces a corresponding rotation of the rotor.
There is no physical contact between the two assemblies.
CAUTION: Do not place magnetic storage
media near the magnet assembly, as it contains a powerful magnet capable of destroying
magnetically recorded material.
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Pressure Manifold
Pressure Gauge
Three-Way Valve
Mounting Plate
Sorbothane
Block
Figure 8.8
Pressure Manifold Assembly
The Pressure Cell includes a
high-pressure manifold
assembly that is connected to
the rheometer frame. The
rigid piping pressure manifold provides strain relief
between the pressure cell
and external high-pressure
connections. It also includes
necessary valves and gauges
for safely pressurizing and
depressurizing the cell. It is
a critical part of the pressure
cell assembly and the pressure cell should not be operated without the manifold in
place. The pressure manifold, shown in Figure 8.8 to
the right, includes the following:
• Mounting plate and
Sorbothane block. The
Sorbathane block is a
flexible material that
provides flex between
the rigid pressure cell
piping assembly and the
rheometer frame.
• 1/8-inch and 1/4- inch
female NPT fittings for
high-pressure connections.
• Three way valve for pressurizing, maintaining cell pressure, and depressurizing the cell.
• Pressure gauge for monitoring pressure in the cell.
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Requirements for External Pressure Source
Figure 8.9
Typical Setup for External Pressurization
Fittings are provided for external pressurization up to 138 bar (2000 psi). A high-pressure source must be
supplied with 1/8-inch or 1/4-inch NPT male fittings for connection to the manifold supplied by TA
Instruments. In addition, a means of isolating the source from the manifold, and of relieving the pressure in
the line from the source to the manifold should be provided. Figure 8.9 below shows a typical set up for
external pressurization.
WARNING: Only use TA Instruments' high-pressure manifold when operating the
pressure cell. Ensure that the manifold can be isolated from the high-pr essure source
provided by the user, and that there is a pressure vent valve in the line between the
source and the manifold.
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Installing and Using the Pressure Cell
Pressure Cell Cup
Rotor Assembly
Tommy Bar
Angled Pipe
Manifold Assembly
with Gauge
Figure 8.10
Entire Pressure Cell Configuration Disassembled
The AR-G2 and AR2000/ex Pressure Cell is shipped with the Rotor installed in the pressure cell cup, and the
high-pressure piping manifold fully assembled. Installing the AR Pressure Cell from it's initial shipped
configuration requires some disassembly. Disassembly instructions are as follows:
• Step 1: Unpack the preassembled pressure cell cup and rotor. Using the spanner (Tommy bar) provided,
remove the rotor assembly from the pressure cell cup, and carefully place the rotor in a safe location. Remove
foam packing material from Cup.
NOTE: All the compression fittings that are used on the manifold assembly have a specific
tightening procedure for the first time the nut is tigh tened on the tubing during the manufacturing
process. Subsequent disassembly and remake of any fitting should be done b y first putting a
reference mark on the nut and the body of the fitting before loosening the fitting. After
reassembly of the fitting to a finger tight condition, the nut should then be tightened with a
wrench so that the mark on the nut aligns with the mark on the body of the fitting. A second
wrench should be used to hold the body of the fitting in place while turning the nut.
• Step 2: Unpack the preassembled piping manifold assembly. Using a wrench, remove the furthest extending
angled pipe from the Tee fitting joining the gas inlet and pressure gauge.
Figure 8.10 below shows the disassembled configuration.
The steps on the next several page provide the instructions needed to install and use the pressure cell.
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Step 1: Install High-Pressure Piping Manifold
Attach
here
Figure 8.11
Attach Manifold to Back of Rheometer
manifold
Manifold
Sorbothane Block
Cap Head Screws
Figure 8.12
Manifold Installed
Manifold
Bracket
The pressure manifold attaches to the lower right
rear as viewed from front of rheometer or left lower
corner when facing rear of the AR rheometer, as
shown in Figure 8.11.
Attach the mounting plate and Sorbothane block to
the two M5 using the cap head screws provided, as
shown in Figure 8.12 below.
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Step 2: Install and Configure Pressure Cell Cup and Rotor
Small
Magnet
Wrench
(Tommy
Bar) Hole
Scribe
Line
Figure 8.14
Rotor Assembly
with Small Magnet
Safety Relief
Angled
Pipe
Peltier
Jacket
Hot Symbol
Smart Swap
Alignment
Line
Figure 8.13
Pressure Cell Cup Installed in Peltier Jacket
Valve
Small
Magnet
Figure 8.15
Orientation of Small Magnet
Follow the instructions below to both install and configure the Pressure Cell Cup and Rotor:
1. Locate the Peltier Concentric Cylinder Jacket. Remove the Peltier Jacket, if it is installed on the AR Instrument.
2. Remove any Peltier Concentric Cylinder cups and remove the two
knurled screws that fasten the standard Peltier cups in place (Note the
standard knurled screws can not be
used with the Pressure Cell).
3. Insert the Pressure Cell cup into the
jacket, with the Safety Relief valve
facing to the rear of the cup. (Note
the "Hot" symbol and white Smart
Swap alignment line are markings on
the front of the Peltier Jacket). Fix
the cup in position in the jacket using
the two hex head screws and hex
keys provided with the Pressure
Cell. See Figure 8.13 to the right.
4. Connect angled high-pressure pipe
to the cell inlet port, ensuring that the straight part of the pipe is vertical as shown in Figure 8.13. Tighten
the compression connector as directed in the NOTE on page 93.
5. Locate the rotor assembly. Place the small magnet onto the rotor
assembly, as shown in Figure 8.14, such that the small magnet is
vertically aligned with the scribe line etched on the collar on the rotor
assembly.
6. Hand-tighten the rotor assembly into the cup. Fully tighten the rotor
until flush with the cup using the wrench (also called a Tommy bar).
7. Position the small magnet on the
rotor to face in the front center
of the Peltier Jacket as shown in
Figure 8.15 to the left.
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8. Install Peltier Jacket on rheometer using Smart Swap Connectors.
Figure 8.16
Aligning the Reference Mark
Reference
Mark
Small
Magnet
Figure 8.17
Magnets Engaging
9. Install the Magnet Assembly onto the shaft of the rheometer.
10. Rotate the draw rod so the magnet assembly reference mark is aligned with the small magnet on the
Rotor. Ensure that the reference mark on the upper
geometry remains aligned with the small magnet by
lightly holding the rheometer draw rod and begin
lowering the rheometer head as shown in Figure
8.16
11. At a gap of about 20 mm between the shoulder on
the rotor assembly, and the underside of the upper
magnet assembly, the magnets in the upper assembly will engage with those in the rotor assembly as
shown in Figure 8.17. (A small noise will be heard
when this happens and a change of a few Newtons
will be seen in the normal force reading.). Immediately stop moving the rotor assembly down and
remove the small magnet.
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Step 3: Positioning Gap and Pressure Cell Calibrations
Once the Pressure Cell cup and rotor have been installed, you will need to position the gap and perform the
calibrations as directed in this section.
CAUTION: The standard calibration routines used by Rheology Advantage for zero gap,
geometry inertia and bearing friction are not suitable for use with the pre ssure cell. When
the pressure cell is selected as the measuring geometry, these routines are either
disabled or are replaced by more appropriate routines. Do not attempt to use or calibrate
the pressure cell unless this geometry is selected.
1. Ensuring that the pressure cell geometry is selected in the software, find the gap zero position. Do not request
the instrument to raise the head to the backoff distance. Set a gap of 3500 µm.
2. When the Pressure Cell is the selected geometry on an AR2000 or AR2000ex, the Gap Zero Mode of normal
force with a value of 5N will be used. This will override any other settings in Rheology Advantage software.
3. Conduct the Bearing Friction Calibration. The bearing friction routine used when the Pressure Cell is selected
as the geometry is slightly different from the standard routine. The calibration should be conducted at a
geometry gap of 3500 µm. The bearing friction calibration must be done again when another measuring
system is used. A typical value for the Pressure Cell should be between 8 and 15 µN.m / (rad/s). This is about
ten times higher than for other geometries.
4. Map the Air Bearing. Perform a rotational mapping at a gap of 3500 µm using the Standard mapping routine.
NOTE: DO NOT USE PRECISION OR EXTENDED MAPPING ROUTINES WITH THE PRESSURE CELL.
CAUTION: It is important that the bearing is re-mapped before any other measuring
system is used.
NOTE: When changing to other geometries, Rheology Advantage does not restore the pr evious
settings. However, the mapping table is cleared and the bearing friction is reset to zero. Any
functions that were previously unavailable are reactivated and the gap zero mode settings are
restored, because the settings were not overwritten.
5. Check the Cell by running peak-hold test at 0.05 rad/s and a duration time of 126 sec. The peak-to-peak
residual torque should not be larger than 100 µN.m.
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Step 4: Loading a Sample
Figure 8.18
Aligning the Reference Mark
Reference
Mark
Small
Magnet
Samples are loaded in the pressure cell after the cell is set up and calibrated. The following steps will detail
the sample loading procedure.
1. Rotate the drawrod so the reference mark on the magnet assembly is facing the front of the instrument.
Raise the rheometer head high enough to place the small magnet on the rotor. Once the small magnet is
in place, raise the rheometer head to the maximum height.
NOTE: DO NOT REMOVE MAGNET ASSEMBLY FROM THE RHEOMETER HEAD. IF IT IS
REMOVED, THE MAPPING WILL NO LONGER BE AS EFFECTIVE, CAUSING AN
INCREASE IN RESIDUAL TORQUE.
2. Remove the Peltier jacket from rheometer.
3. Leaving the small magnet in place, gently remove the rotor from the cup.
4. Load the sample into the cup. For very viscous samples, you may find it easiest to weigh the sample in the
cup, if the sample density is known (this can be done after removing the cup from the jacket).
NOTE: Volume is 9.5 ± 0.5 mL.
5. Ensure that the small magnet is still aligned with
the mark on the rotor assembly.
6. Replace the rotor assembly and fully tighten.
7. Replace the Peltier jacket onto the Smart Swap Base
of the rheometer.
8. Rotate the draw rod so the magnet assembly reference mark is aligned with the small magnet on the
Rotor. Ensure that the reference mark on the upper
geometry remains aligned with the small magnet
by lightly holding the rheometer draw rod and
begin lowering the rheometer head as shown in
Figure 8.18.
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9. At a gap of about 20 mm between the shoulder on the
Figure 8.19
Magnets Engaging
rotor assembly and the underside of the upper magnet
assembly the magnets in the upper assembly will
engage with those in the rotor assembly as shown in
Figure 8.19. (A small noise will be heard when this
happens and a change of a few Newtons will be seen
in the normal force reading.). Immediately stop moving the rotor assembly down and remove the small
magnet.
10. Lower the instrument head to the geometry gap
(default 3500 µm). Do not zero the gap.
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Step 5: Align Manifold and Make Manifold Connections
Figure 8.20
Place to Connect/Disconnect Manifold
Figure 8.21
Connector Used to
Connect/Disconnect Manifold
Finger
Tighten
This
Connector
After the sample is loaded, you will need to align the manifold
as follows. The pressure manifold should only be connected
and disconnected from the cup assembly at the bottom of the
angled pipe connected to the cup as shown in Figure 8.20.
Please refer to the NOTE on page 93.
1. Prior to connecting the pressure manifold to the angled
pipe, slacken off to finger tight the compression connectors on the manifold in order to easily align the manifold
with the pipe mounted on the cup. DO NOT USE EXCESSIVE FORCE TO POSITION THE PRESSURE MANIFOLD.
2. Finger-tighten ONLY the manifold to the angled pipe
mounted on the cup, using the connector indicated in
Figure 8.21.
3. Once this f itting is finger tight, fully tighten all other
compression fittings as directed in the NOTE on
page 93.
4. Finally, fully tighten the angled pipe to the manifold
as directed in the NOTE on page 93.
CAUTION: To avoid putting excessive
force on the pressure cell, make sure that
connection or disconnection between the
pressure cell and the manifold is made at
the breakage point compression connector only (see Figures 8.20 and 8.21. Con-
nection or disconnection should be made at no other point while the pressure cell is
mounted on the rheometer.
NOTE: To disconnect the pressure cell from the manifold, ensure that both the cell and the
manifold are depressurized. Then disconnect the compression connector indicated in Figures
8.20 and 8.21.
WARNING: Before disconnecting the pressure cell from the manifold, ensure that neither
the cell nor the manifold is pressurized, and that both are cool enough to touch.
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