-
CUSTOMER: CUSTOMER ORDER: ITL REFERENCE: DESCRIPTION: Isotech
Model 493 Isothermal Tower Aluminium Fixed Point Cell.
IDENTIFICATION: DATE OF CALIBRATION: From 6th October 2009 to 10th
October 2009 BASIS OF CALIBRATION: The Isothermal Tower has been
inter-compared to one of the Laboratory Reference cells. The
temperature scale in use in this Laboratory is the International
Temperature Scale of 1990 (ITS 90). This laboratory is accredited
in accordance with the recognised International Standard ISO/IEC
17025:2005. This accreditation demonstrates technical competence
for a defined scope and the operation of a laboratory quality
management system (refer joint ISO-ILAC-IAF Communiqué dated
January 2009). The Joint Communique is available on the ILAC
website at www.ilac.org on the publications and resources page.
CERTIFICATE OF CALIBRATION ISSUED BY: ISOTHERMAL TECHNOLOGY
LIMITED. DATE OF ISSUE: 14th October 2009 CERTIFICATE NO:
Approved Signatory Name: Signature:
Page 1of 7
The Northern Temperature Primary Laboratory is the Calibration
Laboratory of Isothermal Technology Limited
This certificate is issued in accordance with the laboratory
accreditation requirements of the United Kingdom Accreditation
Service. It provides traceability of measurement to recognized
national standards and to units of measurement realized at the
National Physical Laboratory or other recognized national standards
laboratories. This certificate may not be reproduced other than in
full, except with the prior written approval of the issuing
laboratory.
-
MEASUREMENTS:
1. The fixed point cell within the Isothermal Tower comprises an
ingot of 99.9999 (6N) pure metal in a very high purity graphite
crucible, all sealed in metal.
Melt and freeze plateaux were observed, using a Standard
Platinum Resistance Thermometer (SPRT) to investigate the slopes of
the melt and freeze curves (ref. Isotech Journal of Thermometry
Volumes 7.1 and 8.1).
2. The cell was also compared to one of the Laboratories
reference cells. For this, a monitor SPRT was placed in each cell.
The reference cell was melted and held at 5˚C above the melt
temperature overnight whilst the Isothermal Tower was melted and
held at 2˚C above the melt temperature overnight. The following day
both cells were put onto their freeze plateau in the prescribed
manner at the same time. The plateau temperatures of the test and
reference cells were recorded for a period of 20 minutes after
stabilisation. The SPRT’s were then exchanged and the readings of
temperature difference between the test cell and the reference cell
recorded for 20 minutes. The SPRT’s were exchanged once more and
readings of temperature recorded as before. Finally the remainder
of the freeze plateau for both the test and reference cells was
recorded to establish that the measurements of temperature
difference had been made on the first 25% of the freeze plateau.
Each freeze plateau lasted in excess of 10 hours. The
inter-comparison was repeated again on subsequent days using
separate freezes.
CERTIFICATE OF CALIBRATION Description: Isotech Model 493
Isothermal Tower Aluminium Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 2 of 7
-
RESULTS:
The temperature of the test cell has been compared to that of
the Isotech Open Primary Reference Aluminium cell which has
traceability to the reference cell of NIST, and for which an
uncertainty of ± 0.80 mK (2s) has been established. The equilibrium
temperature of the calibrated cell differed from that of the
reference cell as follows;
INTER-COMPARISON TEST CELL – REFERENCE CELL
(mK)
1 -1.622
2 -1.749
Mean Difference = -1.686 mK Standard Deviation = +/- 0.127 mK
(2s)
CERTIFICATE OF CALIBRATION Description: Isotech Model 493
Isothermal Tower Aluminium Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 3 of 7
-
UNCERTAINTIES: The principle components of uncertainty in the
inter–comparison of the cells were: TYPE A: (statistical)
1. The short term reproducibility of the SPRT in the cells and
the effects caused by thermal shock during transfer from one cell
to the other.
2. Statistical uncertainties in the resistance measurements,
particularly those due to electrical interference from the furnace
heater and controller.
TYPE B:
3. The effects of impurities. 4. The effects of different
thermal conditions in the furnaces used (ie. temperature gradients)
5. Uncertainties resulting from the bridge measurements.
Reproducibility of the SPRT and the measurements, and
interference effects (1 & 2 above) cause Type A (statistical)
uncertainties. Impurities contribute to the Type B uncertainty in
the freezing point and are estimated from the quality of the
freezing plateau obtained. The uncertainty estimates at
approximately 95 % confidence (2 standard deviations) for the
inter-comparison are given in Table 1. The uncertainty of the
inter-comparison was obtained by combining the component
uncertainties in quadrature (ie. by calculating the square root of
the sum of the squares), and is also at 2 standard deviations.
Table 1.
Type A 1 & 2 ± 0.421 mK
Type B 3, 4 & 5 ± 1.775 mK
Uncertainty of Inter-comparison (2s) ± 1.824 mK
CERTIFICATE OF CALIBRATION Description: Isotech Model 493
Isothermal Tower Aluminium Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 4 of 7
-
The uncertainty of the equilibrium temperature of the calibrated
cell is ±2 mK. (2s), this does not include the mean temperature
difference of the calibrated cell to the reference cell. The
reported expanded uncertainty is based on a standard uncertainty
multiplied by a coverage factor k = 2, providing a level of
confidence of approximately 95%. The uncertainty evaluation has
been carried out in accordance with UKAS requirements.
NOTES:
1. There is a temperature variation with depth below the metal
surface where the ITS 90 defined temperature applies.
2. In the calibrated cell the distance from the metal surface to
the bottom of the re entrant
well is 180 mm ± 5 mm. 3. The hydrostatic temperature variation
of this cell is 0.0016 mK per mm. 4. The correction should be
calculated using the distance between the metal surface and the
mean sensing position of the thermometer in the re entrant well.
5. The ambient temperature was 20 ˚C ± 2 ˚C throughout the
calibration.
6. Throughout the inter-comparison the Zone Controller of the
Isothermal Tower was set to
12.0.
CERTIFICATE OF CALIBRATION Description: Isotech Model 493
Isothermal Tower Aluminium Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 5 of 7
-
29418/3 Isothermal Tower Aluminium Fixed Point Cell MELT PLATEAU
4 17th September 2009 (S.P. 660.8 Deg C, Zone 12.0)
85.1658
85.1659
85.166
85.1661
85.1662
85.1663
85.1664
85.1665
85.1666
85.1667
85.1668
85.1669
85.167
85.1671
85.1672
85.1673
85.1674
85.1675
85.1676
85.1677
85.1678
899600 903200 906800 910400 914000 917600 921200
TIME/SECS
RE
SIS
TA
NC
E/O
HM
S
670SQ/002 Resistance/Ohms 29418/3 Isothermal Tower Aluminium
Fixed Point Cell FREEZE PLATEAU 4
18th September 2009 (S.P. 660.2 Deg C, Zone 12.0)
85.1654
85.1655
85.1656
85.1657
85.1658
85.1659
85.166
85.1661
85.1662
85.1663
85.1664
85.1665
85.1666
85.1667
85.1668
85.1669
85.167
85.1671
85.1672
970000 973600 977200 980800 984400 988000 991600 995200
998800
TIME/SECS
RE
SIS
TA
NC
E/O
HM
S
670SQ/002 Resistance/Ohms
CERTIFICATE OF CALIBRATION Description: Isotech Model 493
Isothermal Tower Aluminium Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 6 of 7
-
29418/3 Isothermal Tower Aluminium Fixed Point Cell MELT PLATEAU
52nd October 2009 (S.P. 661.4 Deg C, Zone 12.0)
85.0742
85.0743
85.0744
85.0745
85.0746
85.0747
85.0748
85.0749
85.075
85.0751
85.0752
85.0753
85.0754
85.0755
85.0756
171000 174600 178200 181800 185400 189000 192600 196200
199800
TIME/SECS
RE
S/O
HM
S
670SQ/014 Resistance/Ohms 29418/3 Isothermal Tower Aluminium
Fixed Point Cell FREEZE PLATEAU 5
5th October 2009 (S.P. 660.0 Deg C, Zone 12.0)
85.0731
85.0732
85.0733
85.0734
85.0735
85.0736
85.0737
85.0738
85.0739
85.074
85.0741
85.0742
85.0743
85.0744
85.0745
85.0746
85.0747
85.0748
85.0749
419500 423100 426700
TIME/SECS
RE
S/O
HM
S
670SQ/014 Resistance/Ohms
CERTIFICATE OF CALIBRATION Description: Isotech Model 493
Isothermal Tower Aluminium Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 7 of 7
-
CUSTOMER: CUSTOMER ORDER: ITL REFERENCE: DESCRIPTION: Isotech
Model 491 Isothermal Tower Tin Fixed Point Cell. IDENTIFICATION:
DATE OF CALIBRATION: From 24th September 2009 to 1st October 2009
BASIS OF CALIBRATION: The Isothermal Tower has been inter-compared
to one of the Laboratory Reference cells. The temperature scale in
use in this Laboratory is the International Temperature Scale of
1990 (ITS 90). This laboratory is accredited in accordance with the
recognised International Standard ISO/IEC 17025:2005. This
accreditation demonstrates technical competence for a defined scope
and the operation of a laboratory quality management system (refer
joint ISO-ILAC-IAF Communiqué dated January 2009). The Joint
Communique is available on the ILAC website at www.ilac.org on the
publications and resources page.
CERTIFICATE OF CALIBRATION ISSUED BY: ISOTHERMAL TECHNOLOGY
LIMITED. DATE OF ISSUE: CERTIFICATE NO:
Approved Signatory Name: Signature:
Page 1of 8
The Northern Temperature Primary Laboratory is the Calibration
Laboratory of Isothermal Technology Limited
This certificate is issued in accordance with the laboratory
accreditation requirements of the United Kingdom Accreditation
Service. It provides traceability of measurement to recognized
national standards and to units of measurement realized at the
National Physical Laboratory or other recognized national standards
laboratories. This certificate may not be reproduced other than in
full, except with the prior written approval of the issuing
laboratory.
-
MEASUREMENTS:
1. The fixed point cell within the Isothermal Tower comprises an
ingot of 99.9999 (6N) pure metal in a very high purity graphite
crucible, all sealed in metal.
Melt and freeze plateaux were observed, using a Standard
Platinum Resistance Thermometer (SPRT) to investigate the slopes of
the melt and freeze curves (ref. Isotech Journal of Thermometry
Volumes 7.1 and 8.1).
2. The cell was also compared to one of the Laboratories
reference cells. For this, a monitor SPRT was placed in each cell.
The reference cell was melted and held at 5˚C above the melt
temperature overnight whilst the Isothermal Tower was melted and
held at 2˚C above the melt temperature overnight. The following day
both cells were put onto their freeze plateau in the prescribed
manner at the same time. The plateau temperatures of the test and
reference cells were recorded for a period of 20 minutes after
stabilisation. The SPRT’s were then exchanged and the readings of
temperature difference between the test cell and the reference cell
recorded for 20 minutes. The SPRT’s were exchanged once more and
readings of temperature recorded as before. Finally the remainder
of the freeze plateau for both the test and reference cells was
recorded to establish that the measurements of temperature
difference had been made on the first 25% of the freeze plateau.
Each freeze plateau lasted in excess of 10 hours. The
inter-comparison was repeated again on subsequent days using
separate freezes.
CERTIFICATE OF CALIBRATION Description: Isotech Model 491
Isothermal Tower Tin Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 2 of 8
-
RESULTS:
The temperature of the test cell has been compared to that of
the Isotech Open Primary Reference Tin cell which has traceability
to the reference cell of NIST, and for which an uncertainty of ±
0.29 mK (2s) has been established. The equilibrium temperature of
the calibrated cell differed from that of the reference cell as
follows;
INTER-COMPARISON TEST CELL – REFERENCE CELL
(mK)
1 -0.448
2 -0.426
Mean Difference = -0.437 mK Standard Deviation = +/- 0.022 mK
(2s)
CERTIFICATE OF CALIBRATION Description: Isotech Model 491
Isothermal Tower Tin Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 3 of 8
-
UNCERTAINTIES: The principle components of uncertainty in the
inter–comparison of the cells were: TYPE A: (statistical)
1. The short term reproducibility of the SPRT in the cells and
the effects caused by thermal shock during transfer from one cell
to the other.
2. Statistical uncertainties in the resistance measurements,
particularly those due to electrical interference from the furnace
heater and controller.
TYPE B:
3. The effects of impurities. 4. The effects of different
thermal conditions in the furnaces used (ie. temperature gradients)
5. Uncertainties resulting from the bridge measurements.
Reproducibility of the SPRT and the measurements, and
interference effects (1 & 2 above) cause Type A (statistical)
uncertainties. Impurities contribute to the Type B uncertainty in
the freezing point and are estimated from the quality of the
freezing plateau obtained. The uncertainty estimates at
approximately 95 % confidence (2 standard deviations) for the
inter-comparison are given in Table 1. The uncertainty of the
inter-comparison was obtained by combining the component
uncertainties in quadrature (ie. by calculating the square root of
the sum of the squares), and is also at 2 standard deviations.
Table 1.
Type A 1 & 2 ± 0.317 mK
Type B 3, 4 & 5 ± 0.673 mK
Uncertainty of Inter-comparison (2s) ± 0.744 mK
CERTIFICATE OF CALIBRATION Description: Isotech Model 491
Isothermal Tower Tin Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 4 of 8
-
The uncertainty of the equilibrium temperature of the calibrated
cell is ±0.80 mK. (2s), this does not include the mean temperature
difference of the calibrated cell to the reference cell. The
reported expanded uncertainty is based on a standard uncertainty
multiplied by a coverage factor k = 2, providing a level of
confidence of approximately 95%. The uncertainty evaluation has
been carried out in accordance with UKAS requirements.
NOTES:
1. There is a temperature variation with depth below the metal
surface where the ITS 90 defined temperature applies.
2. In the calibrated cell the distance from the metal surface to
the bottom of the re entrant
well is 180 mm ± 5 mm. 3. The hydrostatic temperature variation
of this cell is 0.0022 mK per mm. 4. The correction should be
calculated using the distance between the metal surface and the
mean sensing position of the thermometer in the re entrant well.
5. The ambient temperature was 20 ˚C ± 2 ˚C throughout the
calibration.
6. Throughout the inter-comparison the Zone Controller of the
Isothermal Tower was set to
4.0.
CERTIFICATE OF CALIBRATION Description: Isotech Model 491
Isothermal Tower Tin Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 5 of 8
-
29418/1 Isothermal Tower Tin FixedPoint Cell MELT PLATEAU 2
(S.P. 231.6 Deg C, Zone 4.0) 14th August 2009
47.7511
47.7512
47.7513
47.7514
47.7515
47.7516
47.7517
47.7518
47.7519
47.752
47.7521
47.7522
47.7523
47.7524
182500 186100 189700 193300 196900 200500 204100 207700 211300
214900 218500 222100
TIME/SECONDS
RE
SIS
TA
NC
E/O
HM
S
670SQ/002 Resistance/Ohms 29418/1 Isothermal Tower Tin Fixed
Point Cell FREEZE PLATEAU 2
(S.P. 231.0 Deg C, Zone 4.0) 15th August 2009
47.7505
47.7506
47.7507
47.7508
47.7509
47.751
47.7511
47.7512
47.7513
47.7514
47.7515
47.7516
47.7517
47.7518
252600 256200 259800 263400 267000 270600 274200 277800 281400
285000 288600 292200 295800 299400
TIME/SECONDS
RE
SIS
TA
NC
E/O
HM
S
670SQ/002 Resistance/Ohms
CERTIFICATE OF CALIBRATION Description: Isotech Model 491
Isothermal Tower Tin Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 6 of 8
-
29418/1 Isothermal Tower Tin Fixed Point Cell MELT PLATEAU 3
(S.P. 231.6 Deg C, Zone 4.0) 16th August 2009
47.7511
47.7512
47.7513
47.7514
47.7515
47.7516
47.7517
47.7518
47.7519
47.752
47.7521
47.7522
47.7523
47.7524
336000 343200 350400 357600 364800 372000 379200 386400 393600
400800
TIME/SECONDS
RE
SIS
TA
NC
E/O
HM
S
670SQ/002 Resistance/Ohms 29418/1 Isothermal Tower Tin Fixed
Point Cell FREEZE PLATEAU 3
(S.P. 231.0 Deg C, Zone 4.0) 17th August 2009
47.7505
47.7506
47.7507
47.7508
47.7509
47.751
47.7511
47.7512
47.7513
47.7514
47.7515
47.7516
47.7517
47.7518
428200 431800 435400 439000 442600 446200 449800 453400 457000
460600 464200 467800 471400 475000
TIME/SECONDS
RE
SIS
TA
NC
E/O
HM
S
670SQ/002 Resistance/Ohms
CERTIFICATE OF CALIBRATION Description: Isotech Model 491
Isothermal Tower Tin Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 7 of 8
-
29418/1 Isothermal Tower Tin Fixed Point Cell MELT PLATEAU 421st
September 2009 (S.P. 232.8 Deg C, Zone 4.0).
47
47.0001
47.0002
47.0003
47.0004
47.0005
47.0006
47.0007
47.0008
47.0009
47.001
47.0011
364300 367900 371500
TIME/SECS
RE
SIS
TA
NC
E/O
HM
S
670/113 Resistance/Ohms
29418/1 Isothermal Tower Tin Fixed Point Cell FREEZE PLATEAU 4
22nd September 2009 (S.P. 230.0 Deg C, Zone 4.0).
46.9985
46.998646.9987
46.9988
46.9989
46.99946.9991
46.9992
46.999346.9994
46.9995
46.999646.9997
46.9998
46.9999
4747.0001
47.0002
47.000347.0004
47.0005
47.0006
449000 452600 456200 459800
TIME/SECS
RE
SIS
TA
NC
E/O
HM
S
670/113 Resistance/Ohms
CERTIFICATE OF CALIBRATION Description: Isotech Model 491
Isothermal Tower Tin Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 8 of 8
-
CUSTOMER CUSTOMER ORDER: ITL REFERENCE: DESCRIPTION: Isotech
Model 492 Isothermal Tower Zinc Fixed Point Cell. IDENTIFICATION:
DATE OF CALIBRATION: From 14th October 2009 to 20th October 2009
BASIS OF CALIBRATION: The Isothermal Tower has been inter-compared
to one of the Laboratory Reference cells. The temperature scale in
use in this Laboratory is the International Temperature Scale of
1990 (ITS 90). This laboratory is accredited in accordance with the
recognised International Standard ISO/IEC 17025:2005. This
accreditation demonstrates technical competence for a defined scope
and the operation of a laboratory quality management system (refer
joint ISO-ILAC-IAF Communiqué dated January 2009). The Joint
Communique is available on the ILAC website at www.ilac.org on the
publications and resources page.
CERTIFICATE OF CALIBRATION ISSUED BY: ISOTHERMAL TECHNOLOGY
LIMITED. DATE OF ISSUE: 20th October 2009 CERTIFICATE NO:
Approved Signatory Name: Signature:
Page 1of 7
The Northern Temperature Primary Laboratory is the Calibration
Laboratory of Isothermal Technology Limited
This certificate is issued in accordance with the laboratory
accreditation requirements of the United Kingdom Accreditation
Service. It provides traceability of measurement to recognized
national standards and to units of measurement realized at the
National Physical Laboratory or other recognized national standards
laboratories. This certificate may not be reproduced other than in
full, except with the prior written approval of the issuing
laboratory.
-
MEASUREMENTS:
1. The fixed point cell within the Isothermal Tower comprises an
ingot of 99.9999 (6N) pure metal in a very high purity graphite
crucible, all sealed in metal.
Melt and freeze plateaux were observed, using a Standard
Platinum Resistance Thermometer (SPRT) to investigate the slopes of
the melt and freeze curves (ref. Isotech Journal of Thermometry
Volumes 7.1 and 8.1).
2. The cell was also compared to one of the Laboratories
reference cells. For this, a monitor SPRT was placed in each cell.
The reference cell was melted and held at 5˚C above the melt
temperature overnight whilst the Isothermal Tower was melted and
held at 2˚C above the melt temperature overnight. The following day
both cells were put onto their freeze plateau in the prescribed
manner at the same time. The plateau temperatures of the test and
reference cells were recorded for a period of 20 minutes after
stabilisation. The SPRT’s were then exchanged and the readings of
temperature difference between the test cell and the reference cell
recorded for 20 minutes. The SPRT’s were exchanged once more and
readings of temperature recorded as before. Finally the remainder
of the freeze plateau for both the test and reference cells was
recorded to establish that the measurements of temperature
difference had been made on the first 25% of the freeze plateau.
Each freeze plateau lasted in excess of 12 hours. The
inter-comparison was repeated again on subsequent days using
separate freezes.
CERTIFICATE OF CALIBRATION Description: Isotech Model 492
Isothermal Tower Zinc Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 2 of 7
-
RESULTS:
The temperature of the test cell has been compared to that of
the Isotech Open Primary Reference Zinc cell which has traceability
to the reference cell of NIST, and for which an uncertainty of ±
0.52 mK (2s) has been established. The equilibrium temperature of
the calibrated cell differed from that of the reference cell as
follows;
INTER-COMPARISON TEST CELL – REFERENCE CELL
(mK)
1 0.767
2 0.808
Mean Difference = 0.788 mK Standard Deviation = +/- 0.041 mK
(2s)
CERTIFICATE OF CALIBRATION Description: Isotech Model 492
Isothermal Tower Zinc Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 3 of 7
-
UNCERTAINTIES: The principle components of uncertainty in the
inter–comparison of the cells were: TYPE A: (statistical)
1. The short term reproducibility of the SPRT in the cells and
the effects caused by thermal shock during transfer from one cell
to the other.
2. Statistical uncertainties in the resistance measurements,
particularly those due to electrical interference from the furnace
heater and controller.
TYPE B:
3. The effects of impurities. 4. The effects of different
thermal conditions in the furnaces used (ie. temperature gradients)
5. Uncertainties resulting from the bridge measurements.
Reproducibility of the SPRT and the measurements, and
interference effects (1 & 2 above) cause Type A (statistical)
uncertainties. Impurities contribute to the Type B uncertainty in
the freezing point and are estimated from the quality of the
freezing plateau obtained. The uncertainty estimates at
approximately 95 % confidence (2 standard deviations) for the
inter-comparison are given in Table 1. The uncertainty of the
inter-comparison was obtained by combining the component
uncertainties in quadrature (ie. by calculating the square root of
the sum of the squares), and is also at 2 standard deviations.
Table 1.
Type A 1 & 2 ± 0.360 mK
Type B 3, 4 & 5 ± 0.773 mK
Uncertainty of Inter-comparison (2s) ± 0.853 mK
CERTIFICATE OF CALIBRATION Description: Isotech Model 492
Isothermal Tower Zinc Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 4 of 7
-
The uncertainty of the equilibrium temperature of the calibrated
cell is ±1 mK. (2s), this does not include the mean temperature
difference of the calibrated cell to the reference cell. The
reported expanded uncertainty is based on a standard uncertainty
multiplied by a coverage factor k = 2, providing a level of
confidence of approximately 95%. The uncertainty evaluation has
been carried out in accordance with UKAS requirements.
NOTES:
1. There is a temperature variation with depth below the metal
surface where the ITS 90 defined temperature applies.
2. In the calibrated cell the distance from the metal surface to
the bottom of the re entrant
well is 180 mm ± 5 mm. 3. The hydrostatic temperature variation
of this cell is 0.0027 mK per mm. 4. The correction should be
calculated using the distance between the metal surface and the
mean sensing position of the thermometer in the re entrant well.
5. The ambient temperature was 20 ˚C ± 2 ˚C throughout the
calibration.
6. Throughout the inter-comparison the Zone Controller of the
Isothermal Tower was set to
13.0.
CERTIFICATE OF CALIBRATION Description: Isotech Model 492
Isothermal Tower Zinc Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 5 of 7
-
29418-2 Isothermal Tower Zinc Fixed Point Cell MELT PLATEAU 12th
October 2009 (S.P. 420.0 Deg C, Zone 13.0)
63.787
63.7871
63.7872
63.7873
63.7874
63.7875
63.7876
63.7877
63.7878
63.7879
63.788
63.7881
63.7882
63.7883
63.7884
63.7885
63.7886
63.7887
1044500 1048100 1051700 1055300 1058900 1062500 1066100 1069700
1073300
TIME/SECS
RE
SIS
TA
NC
E/O
HM
S
670/113 Resistance/Ohms 29418-2 Isothermal Tower Zinc Fixed
Point Cell FREEZE PLATEAU
13th October 2009 (S.P. 419.0 Deg C, Zone 13.0)
63.786
63.7861
63.7862
63.7863
63.7864
63.7865
63.7866
63.7867
63.7868
63.7869
63.787
63.7871
63.7872
63.7873
63.7874
63.7875
63.7876
63.7877
63.7878
63.7879
63.788
1109000 1112600 1116200 1119800 1123400 1127000 1130600
1134200
TIME/SECS
RE
S/O
HM
S
670-113 Resistance/Ohms
CERTIFICATE OF CALIBRATION Description: Isotech Model 492
Isothermal Tower Zinc Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 6 of 7
-
29418-2 Isothermal Tower Zinc Fixed Point Cell MELT PLATEAU 2
15th October 2009 (S.P. 420.0 Deg C, Zone 13.0)
63.787
63.7871
63.7872
63.7873
63.7874
63.7875
63.7876
63.7877
63.7878
63.7879
63.788
63.7881
63.7882
63.7883
63.7884
63.7885
63.7886
63.7887
1299700 1303300 1306900 1310500 1314100 1317700 1321300 1324900
1328500 1332100 1335700
TIME/SECS
RE
SIS
TA
NC
E/O
HM
S
670-113 Resistance/Ohms 29418-2 Isothermal Tower Zinc Fixed
Point Cell FREEZE PLATEAU 2
16th October 2009 (S.P. 419.0 Deg C, Zone 13.0)
63.786
63.7862
63.7864
63.7866
63.7868
63.787
63.7872
63.7874
63.7876
63.7878
63.788
1366000 1369600 1373200 1376800 1380400 1384000 1387600
1391200
TIME/SECS
RE
SIS
TA
NC
E/O
HM
S
670-113 Resistance/Ohms
CERTIFICATE OF CALIBRATION Description: Isotech Model 492
Isothermal Tower Zinc Fixed Point Cell Identification: UKAS
Accredited Calibration Laboratory No. 0175 N.T.P.L. Northern
Temperature Primary Laboratory, Southport, England Tel. +44 (0)
1704 543830 / 544611 Fax. +44 (0) 1704 544799
CERTIFICATE NO:
Page 7 of 7
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