Isotech, Model 670, Primary SPRT

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SPRT (Standard Platinum Resistance Thermometer), Model 670

Our Best Standard Platinum Resistance Thermometer

-200ºC to 670ºC (1238ºF)

Resistance Value (0ºC): 25.5 Ω
Resistance Ratio: W_GA>1.11807 as required by ITS-90
Sensitivity: 0.1Ω/ºC
Long term drift from 0.001ºC/year
Calibration (UKAS or NIST): By Fixed Point through W4 & W7 subranges

Product Code: 670

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Overview

Specification

Datasheet & Resources

This is the first new thermometer, after the introduction of ITS-90, to be specifically designed to give optimum performance up to the aluminum point. Its construction permits the four internal platinum lead wires to expand and contract in the same manner as those of silver-point thermometers. The all-quartz construction of the support-members gives the most stable performance with minimal drift, and a unique platinum radiation shield prevents heat radiating up the inside of the sheath. The temperature range and design of this new unit means that we offer 25.5 Ω (Ro). The construction, including the coiled sensing element, heat-shunt baffles and light scattering barriers, creates a thermometer of unsurpassed stability. Because the 670 goes beyond the temperature range of oxide growth to the level at which the oxide dissociates, the 670 is filled conventionally with argon containing 10% oxygen.

A 2-metre length of low thermal emf, high temperature, screened cable is connected in the handle, via a strain-relieving transition, to the all pure-platinum construction of the thermometer. Gold-plated U-shaped terminals complete the cable construction, and the 670 is delivered in an elegant soft lined carry-case of our own design.

A 670 is delivered only after a stabilizing process which is complete when the reproducibility of R_TPW is within 0.0005°C after excursions to the extremes of its temperature range. Values of R_TPW and W_GA are routinely provided with the 670.

The 670 can be supplied with R_TPW and W_GA only or with full NIST Traceable or UKAS Accredited calibration.

A comprehensive handbook and tutorial will help you get the very best performance and stability from your 670.