PLATINUM RESISTANCE THERMOMETER PRT

5187SA Platinum Resistance Thermometer PRT. High Precision Platinum Thermometer.
Platinum Resistance thermometer is designed to realize, with the highest accuracy, the International Temperature Scale ITS-90 over the range -189°C to 66O°C.
The design is the result of many years practical experience and cooperation with the National Physical Laboratory

Platinum Resistance Thermometer

Platinum Resistance Thermometer PRT construction

The resistance element is of pure platinum coiled and mounted in a strain free construction. 
The former is of fused silica and great care is taken to ensure freedom from contamination.
All the joints are welded, the four leads from the element to the seal in the thermometer head are heavier gauge platinum thereby avoiding the generation of thermal e.m.f.'s at the junction with the element.
The leads are brought through a hermetic seal at the head of the thermometer and joined via low loss terminals to copper flex in a specially constructed cable with four conductors. 
The cable is made with PTFE insulation to ensure low dielectric loss so that the thermometer may be used with either d.c. or a.c. measuring systems. The terminations are gold plated copper spade tags. The thermometer tube is specially treated to avoid radiation loss by the piping effect in its walls. 
Each thermometer is supplied with a purpose-made carrying case.

Stainless Steel Sheath

To reduce the possibility of damage the Type 5187SA thermometer may be supplied with a protective stainless steel sheath, outside diameter 8-9mm, fitted into the thermometer head by means of three screws. The thermometer is calibrated without the sheath and when this is in position the response time is increased to about 20 seconds

Platinum Resistance Thermometer PRT specifications
Temperature Range:  -189°C to 660°C	Calibration: Suitable for calibration to ITS-90 up to max temp 660.323°C (F.P. Aluminum)
Resistance at 0°C (Rtp):   25 Ohms +/- 0.5Ohm	R(Ga)/R(tp):  Ratio not less than 1.11807 R(Me)/R(tp):  Ratio not greater than 0.844235
Reproducibility: +/-0.001°C	Gas Filling:  Dry air at 1/3 atmosphere
Basic Accuracy:  +/-0.001°C	Dimensions:  Sheath - diameter 6.5 to 7.5 length 480 mm Head - diameter 23 mm length 60 mm Overall length: 540 mm  Immersion depth:  300mm
Self heating:  0.002°C to 0.003°C with 1mA and the thermometer bulb immersed in unstirred water	Leads:  Supplied with 4 meters of PTFE insulated cable fitted with gold plated copper spade tags.
Case Size: 67 x 16 x 7 cm	Net Weight: Including thermometer 1.15kg

The Type 5187SA Platinum Resistance Thermometer maximum calibration will be 660.232°C.
Note: TP - Triple point, MP  -Melting point, FP - Freezing point.