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 | RTPW | 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. |