Uncertainties for:

SPRT's Liquid-in-Glass IPRT's Thermistors Thermocouples Humidity

Uncertainty Budget for SPRT's

2/3/2000   Ar Hg Ga In Sn Cd Zn Al Ag
Type A (in mK)
                  
Bridge Measurement                  
DR from DT 0 0 0 0 0 0 0 0 0.01
realization of repeatability 0.03 0.07 0.02 0.04 0.12 0.12 0.18 0.28 0.5
non-linearity                  
quadrature effects in ac meas. 0 0 0 0 0 0 0 0 0
                      
   Total A 0.03 0.07 0.02 0.04 0.12 0.12 0.18 0.28 0.50
   n 266 260 288 84 302 36 406 130 98
Type B                     
components not divided by sqrt(3) Chemical Impurities 0.05 0.01 0.01 0.05 0.01 0.05 0.17 0.27 0.29
Hydrostatic-head 0.0004 0.0112 0.0032 0.0084 0.0065 0.0090 0.0092 0.0083 0.0097
Propagated TPW 0.0018 0.0075 0.0101 0.0151 0.0182 0.0219 0.0262 0.0376 0.0538
SPRT self-heating 0.0136 0.0146 0.0149 0.0155 0.0159 0.0164 0.0169 0.0184 0.0207
Immersion 0.0033 0.0071 0.0012 0.0033 0.0022 0.0030 0.0027 0.0016 0.0054
Moisture 0 0 0 0 0 0 0 0 0
Gas pressure 0 0 1 E-5 1 E-5 1 E-5 1 E-5 1 E-5 1 E-5 1 E-5
Insulation degradation 0 0 0 0 0 0 0 0 0
                      
Total B divided by sqrt(3) Total B 0.03 0.01 0.01 0.03 0.02 0.03 0.10 0.16 0.17
                      
Combined Standard Uncertainty 0.04 0.07 0.02 0.05 0.12 0.12 0.21 0.32 0.53
                      
Expanded Uncertainty (k=2) 0.08 0.14 0.04 0.10 0.24 0.25 0.41 0.64 1.06

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2/3/2000     TPW
Type A     mK
    Bridge Measurement  
    DR from DT 0
  repeatability of bridge readings (n=560) 0.003
    non-linearity  
  quadrature effects in ac meas. 0
       
    Total A 0.003
       
Type B      
components not divided by sqrt(3)   Chemical Impurities (7N5) 0.0052
    Hydrostatic-head 0.0041
    SPRT self-heating 0.0148
    Immersion 0.0007
    Moisture 0
    Gas pressure 0
  Insulation degradation 0
       
Total B divided by sqrt(3)   Total B 0.01
       
  Combined Standard Uncertainty 0.01
       
  Expanded Uncertainty (k=2) 0.02

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NIST Expanded Uncertainty (k=2) for each of the ITS-90 defining fixed points
 
 
 
Thermometric fixed point
Temperature, K
U (k=2), mK
e-H2 TP
13.8033
0.22
e-H2 VP
17
0.21
e-H2 VP
20.3
0.22
Ne TP
24.5561
0.26
O2 TP
54.3584
0.18
AR TP
83.8058
0.08
Hg TP
234.3156
0.14
H2O TP
273.16
0.02
GA MP
302.9146
0.04
In FP
429.7485
0.1
Sn FP
505.078
0.24
Zn FP
692.677
0.41
Al FP
933.473
0.64
Ag FP
1234.93
1.06

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Maximum Expanded Uncertainties (k=2) of SPRT calibrations at NIST
 
ITS-90 Temperature Subrange
U (k=2), mK
13.8033 K
 to 
0.01 °C
0.62
54.3584 K
to
0.01 °C
0.29
83.8058 K
to
0.01 °C
0.27
234.3156 K
to
29.7646 °C
0.14
0 °C
to
29.7646 °C
0.04
0 °C
to
156.5985 °C
0.10
0 °C
to
231.928 °C
0.24
0 °C
to
419.527 °C
0.41
0 °C
to
660.323 °C
0.64
0 °C
to
961.78 °C
1.06

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Liquid-in-Glass Thermometer Calibration Uncertainties

Table 6: Tolerances and"Estimated" Uncertainties for Low-Temperature Total-Immersion Thermometers

Celsius Scale Graduated Thermometers    
         
Temperature Range °C
Type of Thermometer
Graduation Interval in °C
Tolerance in °C
"Estimated" Uncertainty in °C
-35 to 0
Mercury
1.0 or 0.5
0.5
0.1 to 0.2
-35 to 0
Mercury
0.2
0.4
0.02 to 0.05
-56 to 0
Mercury-thallium
0.5
0.5
0.1 to 0.2
-56 to 0
Mercury-thallium
0.2
0.4
0.02 to 0.05
-200 to 0
Organic Liquid
1
2
0.2 to 0.5 
 
 
 
 
 
Fahrenheit Scale Graduated Thermometers
 
 
 
 
 
Temperature Range °F
Type of Thermometer
Graduation Interval in °F
Tolerance in °F
"Estimated" Uncertainty in °F
-35 to 32
Mercury
1.0 or 0.5
1
0.1 to 0.2
-35 to 32
Mercury
0.2
0.5
0.04
-69 to 32
Mercury-thallium
1.0 or 0.5
1
0.1 to 0.2
-69 to 32
Mercury-thallium
0.2
0.5
0.04
-328 to 32
Organic Liquid
2.0 or 1.0
3
0.3 to 0.5

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Table 7: Tolerances and "Estimated" Uncertainties for Low-Temperature Partial-Immersion Thermometers, where "Estimated" Uncertainties are calculated using values from BS Circular No. 8 (1921).

Celsius Scale Graduated Thermometers    
         
Temperature Range °C
Type of Thermometer
Graduation Interval in °C
Tolerance in °C
"Estimated" Uncertainty in °C
-35 to 0
Mercury
1.0 or 0.5
0.5
0.2 to 0.3
-56 to 0
Mercury-thallium
1.0 or 0.5
0.5
0.2 to 0.3
-90 to 0
Organic Liquid
1
3
0.4 to 1.0
         
Fahrenheit Scale Graduated Thermometers    
         
Temperature Range °F
Type of Thermometer
Graduation Interval in °F
Tolerance in °F
"Estimated" Uncertainty in °F
-35 to 32
Mercury
1.0 or 0.5
1
0.3 to 0.5
-69 to 32
Mercury-thallium
1.0 or 0.5
1
0.3 to 0.5
-130 to 32
Organic Liquid
2.0 or 1.0
5
0.8 to 2.0

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Table 8: Tolerances and"Estimated" Uncertainties for Celsius Total-Immersion Mercury Thermometers

Temperature range in °C
Graduation
interval in °C
Tolerance
in °C
"Estimated"
Uncertainty in °C
 
 
 
 
Thermometers Graduated below 150 °C
0 up to 150
1.0 or 0.5
0.5
0.1 to 0.2
0 up to 150
0.2
0.4
0.02
0 up to 150
0.1
0.3
0.02
 
 
 
 
Thermometers graduated below 300 °C
0 up to 100
1.0 or 0.5
0.5
0.05
Above 100 up to 300
1.0 or 0.5
1
0.05
0 up to 100
0.2
0.4
0.02
Above 100 up to 200
0.2
0.5
0.06
 
 
 
 
Thermometers graduated above 300 °C
0 up to 300
2
2
0.2 to 0.5
Above 300 up to 500
2
4
0.05 to 1.0
0 up to 300
1.0 or 0.5
2
0.16
Above 300 up to 500
1.0 or 0.5
4
0.16

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Table 9: Tolerances and"Estimated" Uncertainties for Fahrenheit Total-Immersion Mercury Thermometers

Temperature range in °F
Graduation
interval in °F
Tolerance
in °F
"Estimated"
Uncertainty in °F
 
 
 
 
Thermometers Graduated below 300 °F
32 up to 300
1.0 or 0.5
0.5
0.1 to 0.2
32 up to 300
0.2
0.4
0.02
32 up to 212
0.1
0.3
0.02
 
 
 
 
Thermometers graduated below 600 °F
32 up to 212
2.0 or 1.0
1
0.2 to 0.5
Above 212 up to 600
2.0 or 1.0
2
0.5
 
 
 
 
Thermometers graduated above 600 °F
32 up to 600
5
4
0.5 to 1.0
Above 600 up to 950
5
7
1.0 to 2.0
32 up to 600
2.0 or 1.0
3
0.2 to 1.0
Above 600 up to 950
2.0 or 1.0
6
0.5 to 1.0

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Table 10: Tolerances and "Estimated" Uncertainties for Celsius Partial-Immersion Mercury Thermometers

Temperature
range in °C
Graduation
interval in °C
Tolerance
in °C
"Estimated"
Uncertainty in °C
 
 
 
 
Thermometers Graduated below 150 °C
0 up to 100
1.0 or 0.5
1
0.1 to 0.3
0 up to 150
1.0 or 0.5
1
0.1 to 0.5
 
 
 
 
Thermometers graduated below 300 °C
0 up to 100
1
1
0.1 to 0.3
Above 100 up to 300
1
1.5
0.5 to 1.0
 
 
 
 
Thermometers graduated above 300 °C
0 up to 300
2.0 or 1.0
2.5
0.5 to 1.0
Above 300 up to 500
2.0 or 1.0
5
1.0 to 2.0