This thermometer uses the volume expansion of gases at temperature changes, in particular the proportional gas expansion of inert gases. These gases can cover temperature changes from –260°C through +700°C and are therefore particularly suitable for high or low temperature measurement. In a closed pressure system the internal pressure change will be proportional to the temperature change, i.e. the pressure will increase when the temperature rises.


The measuring system consists of a bulb with its active volume, a capillary, a bourdon spring and a mechanical gear amplifying the movement of the bourdon tube and transforming it into a rotation. Because the capillary connecting the bulb to the bourdon tube can be bent into any shape and can have a length up to 30m, remote measurement can be executed.


Main features of the gas pressure thermometers are

– extreme temperature range for mechanical thermometers

– good precision and very low measuring hysteresis

– especially when oil filled extremely choc and vibration resistant

– non-polluting & non-contaminating because of use of inert gases

– no aging behavior –> very long mean time between calibrations


These features allow the use in cleanest and health sensitive environments (pharmaceutical & food industry) as well as for extreme temperatures under highest vibrations.





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