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Description
Designed and manufactured by Hart's primary standards
metrologists, the strain-free sensing element in the 5699 meets
all ITS-90 requirements for SPRTs and minimizes long-term drift.
After one year of regular usage, drift is less than 0.008°C
(<0.003°C is typical). Even lower drift rates are possible
depending on care and handling. A fifth wire for grounding is
added to the four-wire sensor to help reduce electrical noise,
particularly for AC measurements. Finally, you can get an improved
version of an old industry-standard Inconel-sheathed SPRT.
The 5699 is constructed with a
0.219-inch-diameter Inconel sheath for high durability and fast
response times. Inside the sheath, the sensing element is
protected by a thin platinum housing that shields the sensor from
contamination from free-floating metal ions found within metal
environments at high temperatures. Reduced contamination means a
low drift rate-even after hours of use in metal-block furnaces at
high temperatures.
At Hart, they use SPRTs every day. They
design them, build them, calibrate them, use them as standards,
and know what it takes to make a reliable performing instrument. |
