Hart Scientific 5695 - Glass capsule SPRT (–200°C to 500°C)

Sometimes you would like to make SPRT measurements but traditional SPRTs are too long or awkward for a particular application. Now Hart makes two versions of our miniature glass capsule SPRTs, which are perfect for cryogenics, calorimetry, and other metrology work requiring small SPRTs.

Both models are true SPRTs. The high-purity platinum wire is hand-wound on a glass cross frame in a strain-free design. The glass capsule is designed to match the thermal expansion of the platinum wire to ensure a true seal at all operating temperatures. The capsules are pressure sealed and come protected in their own maple case. Both models comply completely with ITS-90 and have the following resistance ratios:

W(302.9146K) ³ 1.11807
and
W(234.3156K) £ 0.844235

The 5686 covers temperatures from –260°C to 232°C, so it’s perfect for cryogenic applications. It is 5.8 mm in diameter and 56 mm long.

The 5695 is designed for high-temperature applications requiring a small SPRT. Its range is –200°C to 500°C and its size is 5.2 mm by 68 mm.

Fixed-point calibrations in Hart’s laboratory are available for both models. The Model 5686 may be calibrated from –200°C to 232°C, and the Model 5695 may be calibrated from –200°C to 420°C.

These SPRTs are small but meet customary SPRT performance for reproducibility, reliability, and stability. They solve many of the problems associated with taking precision measurements in situations unsuitable for traditional-length SPRTs. These are excellent calibration instruments.