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5686
Users Guide
Care and Handling Guidelines
Read before removing the SPRT from the case.
SPRT Care
The 5686 capsule Standard Platinum Resistance Thermometer (SPRT) is an extremely delicate
instrument. Great care must be taken in handling the SPRT to maintain calibration accuracy.
Vibration or shock may cause the resistance to increase. A slight tap to the SPRT tip can cause a
change in R
as high as 1 mK. The glass capsule should always be wiped down with 200 proof
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Ethyl Alcohol or other suitable solvent before exposure to high temperatures. Correct handling
of the SPRT will prolong the life expectancy. When not in use, the SPRT should be stored in the
protective case provided by Fluke.
Handling Guidelines
• Keep the thermometer as clean as possible. Always remove any fluid from the sheath
immediately after taking the thermometer from a bath. To remove any possible contaminants,
always wipe the sheath with Ethyl Alcohol or other solvent before submitting the SPRT to high
temperatures.
• Immerse the thermometer in the appropriate liquid for the temperature range. If a dry block is
used, the well diameter should allow the SPRT to comfortably slip in and out without excess
movement. For best results, immerse the thermometer as deep as possible to avoid "stem
effect" (the temperature error caused by the conduction of heat away from the sensor). Do not
submerge the handles.
• Allow sufficient time for the thermometer to stabilize before making measurements. This
allows for the best accuracy.
• Use the correct drive current with the thermometer to prevent error in temperature or
resistance.
• Anneal the thermometer at a temperature slightly higher than the maximum temperature at
which the thermometer will be used when it has been subjected to mechanical or temperature
shock. The SPRT should also be annealed before calibration. If the thermometer is annealed in
a furnace above 660 °C, the furnace should be base metal free.
• Use the protective case provided or other protection when the thermometer is not in use.
• DO NOT subject the thermometer to any physical shock or vibration.
• DO NOT subject the thermometer to temperatures above the highest specified operating
temperature.
• DO NOT expose the thermometer's cables to extreme temperatures.
Operation
General
For best results, be familiar with the operation of the cryostat, calibration bath or furnace and the
read-out instrument. Be sure to follow the manufacturer's instructions for the read-out instrument,
cryostat, and the calibration bath or furnace.
6
Caution
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