The measuring principle is based on the volumetric temperature expansion of the gas filling in the measuring element. The measuring element is firmly connected by a capillary tube with a measuring spring. The spring transfers the expansion of the gas filling by a movement on a dial. Gas-filled dial thermometers are used for temperatures from -80°C up to +600°C. Accuracy is ± 1% of full scale deflection. Gas-filled dial thermometers can be supplied with a capillary line between measuring element and spring of up to 100m length.