<strong>Affordable working standard SPRT</strong>
<ul>
 	<li>Range to aluminum point (660 °C )</li>
 	<li>Inconel™ and platinum sheaths guard against contamination</li>
 	<li>Less than 8 mK/year drift</li>
 	<li>Many calibration options available including by fixed point</li>
 	<li>Fifth wire provides shield ground</li>
</ul>
SPRTs designed by Fluke Calibration are known for their outstanding reliability and minimal long-term drift. They have been calibrated by national (and other primary) laboratories and proven repeatedly to outperform competitive models. Now Fluke Calibration’s 5699 Extended Range Metal-Sheath SPRT combines all the advantages of a Fluke Calibration-designed sensor with the protective sheathing materials that allow your SPRT to be used in virtually any furnace or bath with temperatures as high as 670 °C.

Designed and manufactured by our 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 (&lt; 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.

If you choose not to calibrate the 5699 yourself, a wide variety of options are available from Fluke Calibration’s own primary standards laboratory, including fixed-point calibrations covering any range between –200 °C and 661 °C.

At Fluke Calibration, we use SPRTs every day. We design them, build them, calibrate them, use them as standards, and know what it takes to make a reliably performing instrument. Why buy from anyone else?