Bi-Strip Hygrometer
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Author: Hans-Jürgen Schwarz
English Translation by Sandra Leithäuser
back to Air Humidity Measurement
Abstract[edit]
These hygrometers are simple spiral springs made of a metal spring strip, which is covered with a hygroscopic gel layer on one side. They work similarly to the bi-metal springs, i.e. the hygroscopic side expands due to water absorption and a signal is transmitted proportional to the relative humidity. There are now hygrometer springs that do not even yield at a permanent exposure of 100% RH. These metal springs and their absorptive layer have been specially adjusted to reach a low hygroscopic hysteresis and the same accuracy as the hair hygrometer.