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Standard Platinum Resistance Thermometers (SPRTs) are used to interpolate temperature very accurately in the range of -189.3442°C to 660.323°C on the International Temperature Scale of 1990 (ITS-90).
AccuMac's AM1850-25 SPRT measures from -200 to +500 °C and features a very low drift rate.
The AM1850-25 is used worldwide as standard or reference probe to calibrate other thermometers and to measure temperature precisely in primary and secondary laboratories.
100 ohm SPRTs offer more sensitivity or achieve a better resolution for the same amount of temperature change while 25 ohm SPRTs offer excellent durability and stability over time.
For example for approximately every 1 °C change in temperature, the 100 ohm SPRT will have about a 0.4 ohm change in resistance and a 25 ohm SPRT will only have about 0.1 ohm change. The 100 ohm SPRT has a change in resistance that is 4 times larger than the 25 ohm SPRT.
Primary laboratories often use Thermometry Bridges to read this change in resistance and their equipment may have up to 6-10 decimal places which offers these facilities excellent resolution.
Industrial users often use readouts that are not as advanced and will therefore choose a 100 ohm SPRT.
The 25 ohm SPRT sensor has thicker platinum wires compared to the 100 ohm sensor. These thicker/bigger wires are more shock resistant and hence more stable.
Therefore generally speaking 25 ohm SPRTs are more stable and 100 ohm SPRTs are more sensitive. 25 ohm SPRTs are popular with Primary labs and 100 ohm SPRTs tend to be more popular with commercial labs.
It takes decades of scientific expertise and original craftsmanship to create these world class products.
To reach the best performance in stability and repeatability, the sensing element and sensor support are specially designed to protect the platinum sensing wire from contamination - all components used in each SPRT are cleaned to an extremely high standard before and during assembly.
The gas mixture fill in the thermometer reduces any sensor wire oxidation to as low as possible.
Every SPRT is fully tested for stability after manufacture.
This world class probe meets all the ITS-90 criteria for a standard thermometer.
Inconel sheath 6.35 mm x 480 mm Probe
Alpha 0.003925, Rtp/R0 25
Comes complete with a wooden carrying case that has a customised foam insert.
Very competitive pricing.
Read the attached data sheet or contact Teltherm for further assistance.