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DEFINING FIXED POINTS AND RELATED DATA
ITS 90 TEMPERATURE
PRESSURE
COEFFICIENT
FIXED POINT
°C
K
mK/bar
mK/m HEAD
OF
SUBSTANCE
ITL CELL DESIGNATION
SUITABLE
APPARATUS FOR
CELL
OPERATION
ARGON TP
-189.3442
83.8058
(NOT AVAILABLE FROM ITL)
MERCURY TP
-38.8344
234.3156
+5.4
+7.1
ITL-M-17724
ITL-M-17725
WATER TP
0.01
273.16
-7.5
-0.73
ITL 811
ITL-M-18233
GALLIUM MP
29.7646
302.9146
-2.0
-1.2
ITL-M-17401
ITL-M-17402A
INDIUM FP
156.5985
429.7485
+4.9
+3.3
ITL-M-17668
ITL-M-17701/3/4
TIN FP
231.928
505.078
+3.3
+2.2
ITL-M-17669
ITL-M-17701/3/4
ZINC FP
419.527
692.677
+4.3
+2.7
ITL-M-17671
ITL-M-17701/2*/3
ALUMINIUM FP
660.323
933.473
+7.0
+1.6
ITL-M-17672
ITL-M-17702**
SILVER FP
961.78
1234.93
+6.0
+5.4
ITL-M-17673
ITL-M-17702**
COPPER FP
1084.62
1357.77
+3.3
+2.6
ITL-M-17674
ITL-M-17705
NOTES:
1.
TP = Triple Point, MP = Melting Point, FP = Freezing Point
2.
Pressure corrections that apply to triple point and to other sealed-cell measurements are determined solely by the
pressure
head of material in the cell; variability of atmospheric pressure has no effect on the measurements.
*
Furnace with potassium heat-pipe for zinc freezing point.
**
Furnace with either potassium or sodium heat pipe at aluminium and silver freezing points.
