Isotech ITL- M-17702 User manual

HIGH TEMPERATURE
FURNACE HANDBOOK
ISSUE 8 - 05/05
Page 1 of 37
HIGH
TEMPERATURE FURNACE
MODEL ITL- M-17702
This manual is issued under the authority of
Mr. J. P. Tavener, Managing Director
This manual refers to the following cells
Aluminium Freeze Point Cell
Silver Freeze Point Cell
Copper Freeze Point Cell
The company is always willing to give technical advice and assistance where appropriate.
Equally, because of the programme of continual development and improvement we reserve
the right to amend or alter characteristics and design without prior notice. This publication is
for information only.
Isotech North America
158 Brentwood Drive, Unit 4
Colchester, VT 05446
Phone: [phone]
Fax: [phone]
[email protected]
www.isotechna.com

HIGH TEMPERATURE
FURNACE HANDBOOK
ISSUE 8 - 05/05
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CONTENTS
PAGE NO:
Guarantee 3
EMC Information 4
Health and Safety Instructions 5
High Temperature Furnace, Certificate of Test 6
Sectional View of Transport Clamp 7
Cautionary Note 8
The High Temperature Furnace 9 - 10
Figure 1 - Sealed Metal Freezing-Point Cell 11
Figure 2 - Sealed Metal Freezing-Point Cell Body Dimensions 12
Figure 3 - High Temperature Furnace 13
Realising the Following Fixed Points: Aluminium & Silver 14 - 15
Figure 4 - Typical Melt/Freeze Sequence 16
Cell Handling 17 - 20
High Temperature Furnace Cell Assembly 21
Fault Finding and After Sales Services 22
Spare parts 23
Servicing the High Temperature Furnace 24
Thermometric Fixed Points - A Tutorial 25 - 27
Defining Fixed Points and Related Data 28
General Note on Isotech Metal Freeze Point Cells 29
Precautions to Prevent Devitrification of Quartz Envelopes 30
General Comment 31
Additional Services and Information 32
Appendix 1 33
Appendix 2 34
Appendix 3 35
Using the PC Interface 36
Cal Notepad 37 - 38

HIGH TEMPERATURE
FURNACE HANDBOOK
ISSUE 8 - 05/05
Page 3 of 37
GUARANTEE
This instrument has been manufactured to exacting standards and is guaranteed for twelve
months against electrical break-down or mechanical failure caused through defective material or
workmanship. The guarantee does not cover failure caused by misuse. In the event of failure
covered by this guarantee, the instrument must be returned, carriage paid, to the supplier for
examination, and will be replaced or repaired at our option.
FRAGILE CERAMIC AND/OR GLASS PARTS ARE NOT COVERED BY THIS GUARANTEE
INTERFERENCE WITH THIS INSTRUMENT, OR FAILURE PROPERLY TO MAINTAIN IT, MAY
INVALIDATE THIS GUARANTEE
RECOMMENDATION
The life of your ISOTECH Instrument will be prolonged if regular maintenance and cleaning to
remove general dust and debris is carried out.
Serial No:....................................................
Date:...........................................................
www.isotechna.com
[email protected]
Fax: [phone]
Phone: [phone]
Colchester, VT 05446
158 Brentwood Drive, Unit 4
Isotech North America

HIGH TEMPERATURE
FURNACE HANDBOOK
ISSUE 8 - 05/05
Page 4 of 37
mailto:[email protected]
EMC INFORMATION
This product meets the requirements of the European Directive on Electromagnetic
Compatibility (EMC) 89/336/EEC as amended by EC Directive 92/31/EEC. To ensure
emission compliance please ensure that any serial communications connecting leads
(RS232 or RS422 or 485) are fully screened.
The product meets the susceptibility
requirements of EN 50082-1, criterion
C.
ELECTRICAL SAFETY
This equipment must be correctly earthed.
This equipment is a Class 1 Appliance. A protective earth is used to ensure the conductive
parts cannot become live in the event of a failure of the insulation.
The protective conductor of the flexible mains cable which is coloured green/yellow MUST
be connected to a suitable earth.
The Blue conductor should be connected to Neutral and the Brown conductor to Live (Line).
Warning: Internal mains voltage hazard. Do not remove the panels.
There are no user serviceable parts inside. Contact your nearest Isotech agent for repair.
Voltage transients on the supply must not exceed 2.5kV.

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FURNACE HANDBOOK
ISSUE 8 - 05/05
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HEALTH AND SAFETY INSTRUCTIONS
1. Read all of this handbook before use.
2. Wear appropriate protective clothing.
3. Operators of this equipment should be adequately trained in the handling of hot and
cold items and liquids.
4. Do not use the apparatus for jobs other than those for which it was designed, ie. the
calibration of thermometers.
5. Do not handle the apparatus when it is hot (or cold), unless wearing the appropriate
protective clothing and having the necessary training.
6. Do not drill, modify or otherwise change the shape of the apparatus.
7. Do not dismantle the apparatus.
8. Do not use the apparatus outside its recommended temperature range.
9. If cased, do not return the apparatus to its carrying case until the unit has cooled.
10. There are no user serviceable parts inside. Contact your nearest Isotech agent for
repair.
11. Ensure materials, especially flammable materials are kept away from hot parts of the
apparatus, to prevent fire risk.
12. Ensure adequate ventilation when using oils at high temperatures.

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FURNACE HANDBOOK
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HIGH TEMPERATURE FURNACE
CERTIFICATE OF TEST
SERIAL NO:
Prior to despatch the following tests were carried out:
Insulation Test: M ΩDate:
Earth Impedance: ΩDate:
Temperature cycle to maximum temperature: Date:
Communication's test (if applicable): PASS Date:
Laboratory Test at °C the profile was optimised
Main controller offset °C
Date:
Comments or concessions:
Controller parameters are listed in an appendix of the handbook.
The above serial no. furnace was tested and found to comply with the specifications.
Signature:

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FURNACE HANDBOOK
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EVERY EFFORT HAS BEEN MADE TO PACKAGE THIS UNIT FOR TRANSPORT AND TO
ENSURE ITS GOOD CONDITION ON ARRIVAL AT ITS DESTINATION.
BEFORE COMMISSIONING IT IS NECESSARY TO REMOVE THE FURNACE CORE
TRANSIT CLAMP. TO AVOID DAMAGE PLEASE FOLLOW INSTRUCTIONS:
1. Slacken the central nut using the required tube spanner; the insertion of a
screwdriver through the tube spanner will prevent the central stud turning.
2. Remove the 3 screws securing the transit clamp to the top of the unit. Slacken each
screw equally by degrees and then completely remove the screws.
3. Gently lift the transit clamp vertically; a central tube which has secured the furnace
core will then slide out. The 3 screws should then be replaced in the top of the unit
4. Normal commissioning procedure may now be followed.
5. Keep the transit clamp and use it if the furnace is ever transported.
CAUTIONARY NOTE

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FURNACE HANDBOOK
ISSUE 8 - 05/05
Page 8 of 37
PRODUCTS OF ISOTHERMAL TECHNOLOGY LTD ARE INTENDED FOR TECHNICALLY
TRAINED AND COMPETENT PERSONNEL FAMILIAR WITH GOOD LABORATORY
PRACTICE. IT IS EXPECTED THAT PERSONNEL USING THIS EQUIPMENT WILL BE
KNOWLEDGEABLE AND SKILFUL IN THE MANAGEMENT OF APPARATUS WHICH MAY
BE UNDER POWER OR UNDER EXTREMES OF TEMPERATURE (MOLTEN METALS,
CRYOGENIC LIQUIDS, ETC.) AND WILL APPRECIATE THE HAZARDS WHICH MAY BE
ASSOCIATED WITH, AND THE PRECAUTIONS TO BE TAKEN WITH, SUCH
EQUIPMENT.
ELECTRICAL INSTALLATION
THE FURNACES HAVE BEEN DESIGNED FOR CONVENIENT USE AND MAY BE
PLUGGED TO A STANDARD THREE-PIN 13-AMPERE SOCKET. THEY ARE SUPPLIED
SUITABLE FOR THE U.K. MAINS WHICH HAS LIVE, NEUTRAL AND EARTH LINES.
THIS EQUIPMENT MUST BE EARTHED
THE FURNACE IS SUPPLIED WITH A FUSE CARRIER FITTED WITH A NEUTRAL LINK.
THIS IS CLEARLY LABELLED AND IS FOR USE WITH A MAINS SYSTEM WITH A
NEUTRAL LINE, SUCH AS THE UK SUPPLY. IF THE FURNACE IS TO BE USED ON A
SYSTEM WHERE BOTH SUPPLY LINES ARE LIVE WITH RESPECT TO EARTH THEN
THE NEUTRAL FUSE LINK SHOULD BE REPLACED WITH A FUSE. A SPARE FUSE IS
SUPPLIED WITH THE FURNACE.

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FURNACE HANDBOOK
ISSUE 8 - 05/05
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THE HIGH-TEMPERATURE FURNACE
The high-temperature furnace for realisation of metal freezing points is based on the heat-
pipe. It is furnished with two independent control systems, one for temperature control and
the other for over-temperature protection.
Proportional, integral and derivative adjustments for the controller Eurotherm 2604 and the
means for obtaining optimum settings, are described in the manufacturer's manual, which is
included as part of this manual. These parameters are initially adjusted to optimal conditions
for the Isotech Laboratory environment (ambient temperature of 20 ±2°C) in which the
furnace was tested prior to shipment.
The furnace has an over-temperature cut-off controller. Its purpose is to establish an upper
temperature limit after which all systems power will be shut down to protect the system from
the effects of possible operating controller failure.
In use:
a. The over-temperature controller should be set at a temperature approximately 50°C
higher than the operating controller setting.
b. To turn on system power at start up (or as required), it is necessary to actuate the
front panel off/on switch and also to depress the red reset button.
To adjust the over temperature trip point press the UP and Down keys to modify the SP
value to the desired temperature.
On furnaces with the 2216 controller fitted, the model type is shown on the controller at
power up, it is necessary to use the UP and DOWN keys to modify the value.

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FURNACE HANDBOOK
ISSUE 8 - 05/05
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A further safety device is provided in the furnace and is accessible by removing the top
panel and some fibre insulation. It comprises a gold wire (Potassium Heat Pipe only) in
series with the primary power circuit and is essentially in thermal contact with the furnace
core. Its function is to melt if both other control systems fail. This thermal fuse should not
be replaced after failure until the causative fault has been understood and corrected! The
terminal posts for fuse-connection are sited on the outer shell of the furnace assembly facing
the rear panel.
A section through the sealed type of metal freezing-point cell used in the furnace is shown in
Figure 1 and cell external dimensions are specified in Figure 2.
Figure 3 shows a section through the furnace (not to scale) together with the layout of the
controllers and power switch on the front panel.
The furnace is equipped with a thermometer pre-heating tube.

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FURNACE HANDBOOK
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FIGURE 1
SEALED METAL FREEZING POINT CELL
A High-purity graphite crucible and cover
B High-purity graphite sleeve
C High-purity metal
D Fused-quartz envelope, filled to give a pressure of 1 standard atmosphere at the metal
freezing temperature

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FURNACE HANDBOOK
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FIGURE 2
SEALED METAL FREEZING-POINT CELL APPROXIMATE BODY DIMENSIONS

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FURNACE HANDBOOK
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FIGURE 3
A. Cooling Coil
B. Heat Pipe Furnace
C. Gold Fuse (for Potassium Heat Pipe only)
D. Control Thermocouple
E. Over-temperature thermocouple
F. Heating Element
G. Fibrewool Insulation
H. Furnace Filler Pipe
I. Controller
J. Over-temperature controller
K. Mains Switch
L. Insulation Block
M. Insulation Block
REALISING THE FOLLOWING FIXED POINTS: ALUMINIUM, SILVER AND COPPER

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FURNACE HANDBOOK
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Page 14 of 37
Aluminium and Silver metals are characterised by a relatively short supercool (supercool is
the characteristic of a freezing pure metal to remain liquid at a temperature below that at
which the solid melts). The supercool of these metals can be expected to be less than
0.5°C. The typical supercool for copper is 1.5°C t o 2.5°C.
The cell is placed in the furnace, suitable insulation and cover added and a monitoring
thermometer inserted, (for Al + Ag a HT SPRT (High Temperature Standard Platinum
Resistance Thermometer) and for Cu a standard thermocouple of suitable type and
construction). Initially the furnace controller should be set 5-10°C below the nominal fixed
point temperature and left to stabilise. At this point the monitor thermometer is used to
calibrate the furnace controller which is then set to be +1 to +2°C above the fixed point
temperature allowing for any controller offset. The temperature rise is monitored with a
bridge and/or recorder connected to the thermometer.
Following the melt arrest, the temperature of the cell will rise to the controlled temperature.
The metal in the cell is now entirely in the liquid phase and may be maintained in this
condition for any desired period of time, for example, to accommodate to a calibration
schedule. For optimal realisation of the freeze plateau the molten cell should be left at +5°C
overnight prior to freezing the cell the next day.
To freeze, the furnace controller is set below the actual freeze temperature (for pure metals,
melt and freeze temperatures are theoretically identical). The suggested setting is 1°C
below the freeze temperature; this is, assuredly, below the bottom of the supercool. The
furnace is allowed to cool to this new setpoint temperature, taking typically 30 to 45 minutes
to do so.
When the monitor indicates that the cell is at, or below, its freeze temperature, the monitor is
removed to a rack or the pre-warming tube of the furnace and replaced by a cold rod of
quartz. This initiates nucleation. After 2 minutes the rod can be removed and replaced by
the monitor again.
This procedure creates a radial freeze from the inside and outside walls of the cell towards
the centre.
A typical melt/freeze sequence is shown in Figure 4.
If the cell is left too long in the furnace without initiating the freeze as described above,
nucleation will occur and the cell will begin to freeze from the bottom of the cell upwards.
This will result in a short, imperfect, plateau and, moreover, give an incorrect value of freeze
point (typically 10mK below that expected).

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FURNACE HANDBOOK
ISSUE 8 - 05/05
Page 15 of 37
Depending upon factors such as furnace control and the number of thermometers
successively loaded into the cell, plateau durations between an hour and many hours may
be achieved. Thermometers may be preheated prior to transfer to the cell. A pocket is
provided in the furnace for this purpose. It is wise to ascertain from time to time that the
plateau is still in existence, by checking the cell temperature with the monitoring
thermometer at intervals within the measurement sequence. Let us suppose that Th
m
is the
monitoring thermometer and Th
1
...
n
are thermometers to be calibrated.
If n=2 a suitable sequence might be:-
Th
m
, Th
1
, Th
m
, Th
2
, Th
m
and if n=4
Th
m
, Th
1
, Th
2
, Th
m
, Th
3
, Th
4
, Th
m
The Th
m
measured last should be equal in indication to that of the Th
m
measured first to
ensure that the plateau has been present for Th
1
, etc.
At the temperatures of Indium, Lead and Zinc it is generally permissible to withdraw a
thermometer, of type Isotech 909, directly into room temperature. After exposure to
Aluminium and Silver Point temperatures, slow cooling is vital to ensure that thermometer
characteristics remain unaltered.
A USEFUL HINT
When first creating freezes use large under settings - typically 3 to 5°C BELOW the freeze
plateau. The result will be a shorter freeze time than ideal, but will engender confidence in
establishing a plateau. Once familiar with the procedure using coarse settings, on
subsequent exercises bring the setting of the controller closer to the known freeze
temperature to increase the plateau length.
There follows later a tutorial about Fixed Points.

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FURNACE HANDBOOK
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FIGURE 4
TYPICAL MELT/FREEZE SEQUENCE
A. Initial temperature rise
B. Temperature arrest during melt
C. Furnace-controlled temperature
D. Temperature drop caused by furnace controller adjustment to initiate freeze
E. Depth of supercool (particularly pronounced for tin)
F. Plateau showing constant temperature during freeze
G. End of freeze plateau. Temperature drops to setting of furnace for freeze.

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FURNACE HANDBOOK
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CELL HANDLING
In order to facilitate introduction to, and removal from, the furnace, Isotech provides, for each
cell, supplementary equipment largely comprising an Inconel basket with detachable handle.
To prevent the cell-surface becoming discoloured, it is recommended that, before using the
cell, the basket and insulation be placed in the furnace and the furnace be taken to above
the cell working temperature for at least 2 hours. This operation outgasses the basket and
insulation, which may smoke and discolour during this first temperature excursion. The cell
can then be inserted into the basket in readiness for use. Please read section concerning
cleaning of cells prior to use and devitrification of the quartz. If removing the cell with a
thermometer in its pocket (e.g. tin cell), extreme caution is necessary in applying support by
means of the diametrally-pivoted handle. The handle will need to be maintained in a non-
vertical plane while being used for removing and replacing the assembly.
CELL KIT
Basket, handles, discs of ceramic insulation, inconel baffles and platinum foil discs if
required.
Sketches shows the recommended assembly of the cell basket (and insulation discs) in a
furnace core.

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FURNACE HANDBOOK
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DRAWING 410-07-00 ISSUE 5
CELL BASKET (SHORT) GENERAL ASSEMBLY
DRAWING 410-07-01 ISSUE 3
TYPE B OPTIMAL CELL BASKET GENERAL ASSEMBLY

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FURNACE HANDBOOK
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DRAWING 410-07-04 ISSUE 1
TYPE C OPTIMAL CELL BASKET GENERAL ASSEMBLY

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FURNACE HANDBOOK
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