Primary Standards Selection Guide

Primary Standards for Temperature Calibration

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	R_TPW	Description
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 Ω	0 °C to 1070 °C, quartz sheath
5685	2.5 Ω	0 °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 Cased	156.5985 °C
5945	Mini Freezing Point of Tin, Metal Cased	231.928 °C
5946	Mini Freezing Point of Zinc, Metal Cased	419.527 °C
5947	Mini Freezing Point of Aluminum, Metal Cased	660.323 °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
7196	Affordable 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
1595A	0.06 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.