Ser No. 151
Platinum Resistance thermometer
model WS104 manufactured by
Rosemount Engineering Company Limited, Durban Road, Bognor Regis,
Sussex, England. June 1966.
This Inconel Sheathed Thermometer is designed for routine high precision measurements where a standard thermometer would prove too expensive and/or fragile for repeated use. The sensing element is constructed from highly pure platinum wire held within a ceramic former in a completely unstrained condition. Both current and potential leads are fitted to enable the most accurate measurements to be made. The thermometer is capable of being calibrated to the National Physical Laboratory Type 2 Test. This test implies a short term stability up to its maximum temperature of better than 0.01 deg. C. Long term stability is certainly well within the specified figure.
Temperature Range - 183°C to +500°c.
Ice Point Resistance 25.5 ohms.
(R100/Ro ) 1.3920 declared individually.
For drawing SD 456 showing dimensions and specification click here
Routine Calibration of Thermocouples, Mercury in Glass or other resistance thermometers etc. Freezing Point_and Boiling Point determinations, Calorimetry, Thermodynamic Research, Determination of heats of reaction, Routine Precision Calibrations in actual industrial processes.
The resistance of a metal wire increases with temperature. By passing a current (AC or DC) through it and measuring the voltage with a suitable bridge or voltmeter, the reading can be converted to temperature using a calibration equation. Platinum is used as it has the most stable resistance-temperature relationship over the largest temperature range.
I was given this instrument which formed part of a large collection amassed by Bob Evans by his daughter Alice Kirby. I have checked that it works using a digital multimeter, but have not yet tried it with a more accurate potentiometric bridge.