Primary Standards Selection Guide

Primary Standards for Temperature Calibration
Primary Standards Selection Guide
The defining instruments of the ITS-90 (International Temperature Scale of 1990) are Standard Platinum Resistance Thermometers (SPRT) and ITS-90 fixed point cells. SPRTs are calibrated in fixed point cells to provide the highest possible temperature accuracy. Primary standards offered by Fluke Calibration include Standard Platinum Resistance Thermometers, ITS-90 fixed point cells and all of the equipment and services necessary for calibration traceable to the ITS-90, including, furnaces, baths, resistance bridges, and standard resistors.
 Standard Platinum Resistance Thermometers (SPRTs) 
Model RTPWDescription 
5681 25.5 Ω–200 °C to 670 °C, quartz sheath 
5683 25.5 Ω–200 °C to 480 °C, quartz sheath  
5684 0.25 Ω0 °C to 1070 °C, quartz sheath  
5685 2.5 Ω0 °C to 1070 °C, quartz sheath  
5698 25.5 Ω–200 °C to 670 °C, working standard, , quartz sheath  
5699 25.5 Ω–200 °C to 670 °C, high temperature, metal sheath
5686 25.5 Ω–260 °C to 232 °C, glass capsule


ITS-90 Fixed-point cells 
Model Description Temperature 
Triple point of water cells
5901A-G TPW Cell, 12 mm ID with handle, glass shell 0.01 °C 
5901A-Q TPW Cell, 12 mm ID with handle, quartz shell 0.01 °C 
5901C-G TPW Cell, 13.6 mm ID with handle, glass shell 0.01 °C 
5901C-Q TPW Cell, 13.6 mm ID with handle, quartz shell 0.01 °C 
5901D-G TPW Cell, 12 mm ID, glass shell 0.01 °C 
5901D-Q TPW Cell, 12 mm ID, quartz shell 0.01 °C 
5901B-G TPW Cell, mini, glass shell 0.01 °C 
Standard size fixed-point cells
5900E TP Mercury, SST –38.8344 °C 
5904 Freezing Point of Indium 156.5985 °C 
5905 Freezing Point of Tin 231.928 °C 
5906 Freezing Point of Zinc 419.527 °C 
5907 Freezing Point of Aluminum 660.323 °C 
5908 Freezing Point of Silver 961.78 °C 
5909 Freezing Point of Copper 1084.62 °C 
5924 Open Freezing Point of Indium 156.5985 °C 
5925 Open Freezing Point of Tin 231.928 °C 
5926 Open Freezing Point of Zinc 419.527 °C 
5927A Open Freezing Point of Aluminum 660.323 °C 
5928 Open Freezing Point of Silver 961.78 °C 
5929 Open Freezing Point of Copper 1084.62 °C 
5943 Melting Point of Gallium, SST 29.7646 °C 
Mini triple point of water and fixed-point cells
5901B Mini Triple Point of Water 0.01 °C 
5914A Mini Freezing Point of Indium 156.5985 °C 
5915A Mini Freezing Point of Tin 231.928 °C 
5916A Mini Freezing Point of Zinc 419.527 °C 
5917A Mini Freezing Point of Aluminum 660.323 °C 
5918A Mini Freezing Point of Silver 961.78 °C 
5919A Mini Freezing Point of Copper 1084.62 °C 
5944 Mini Freezing Point of Indium, Metal Cased156.5985 °C 
5945 Mini Freezing Point of Tin, Metal Cased 231.928 °C 
5946 Mini Freezing Point of Zinc, Metal Cased 419.527 °C 
5947Mini Freezing Point of Aluminum, Metal Cased660.323 °C


Maintainance apparatus
Model Features/Use 
7012 Maintains: triple point of water and gallium cells.
Comparisons: –10 °C to 110 °C. 
7037 Maintains: triple point of water and gallium cells.
Comparisons: –40 °C to 110 °C. 
7312 Maintains: two TPW cells. Compact size, runs quietly.
Comparisons: –5 °C to 110 °C. 
7341 Maintains: triple point of mercury cell.
Comparisons: –45 °C to 150 °C. 
9210 Maintains: mini triple point of water.  
Comparisons: –10 °C to 125 °C. 
9230 Maintains: stainless steel gallium cell.
Comparisons: 15 °C to 35 °C. 
9260 Maintains: indium, tin, zinc, and aluminum cells.
Comparisons: 50 °C to 680 °C. 
9114 Maintains: indium, tin, zinc, and aluminum cells.
Comparisons: 100 °C to 680 °C. 
9115 Maintains: aluminum and silver cells.
Comparisons: 550 °C to 1000 °C. 
9116 Maintains: aluminum, silver, gold, and copper cells.
Comparisons: 400 °C to 1100 °C. 
9117 Anneals SPRTs, HTPRTs, and thermocouples to 1100 °C.
Protects them against contamination from metal ions. 
Boiling point of liquid nitrogen 
7196Affordable substitute for a triple point of argon system. Provides for low-temperature comparison calibrations at approximately –196 °C with uncertainties of 2 mK. 
Resistance bridge 
1595A0.06 ppm accuracy for calibration of SPRTs and thermistors. 
Standard resistors 
742A Excellent performance without oil or air baths. Values from 10 ohm to 100 megohm. 
5430 Highest stability oil-filled resistors (< 2 ppm/year drift). AC cal uncertainty to 3 ppm. 
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