A PORTABLE DIELECTRIC-HYGROMETER OF PAPER

Abstract

This instrument is a portable dielectric-hygrometer that consists of 1 Mc. oscillator and double resonant circuit (I. B. Circuit), and preferable to measure moisture content of running web. Charac teristics of this instrument are to be able to measure moisture contents from only dielectric constant variance and to be not influenced by resistance varisance of paper even at relatively high moisture range. The followings are some of the test results.
(1) Appropriately adjusting the sensitivity vari-con of this instrument, it is capable of measuring not only ordinary moisture contents (3-14%), but also relatively high moisture contents (to about 35%).
(2) It needs appropriate calibration, because other paper properties besides the moisture content also enter the results.
(3) The deviations of measured moisture contents amount to ± 0.3-0.4 % for ordinary range (3-14%) and ±1.5 % for high moisture range (20-35 %).
(4) The temperature effect at the range of 15°C to 35°C is so small that we can neglect the deviations caused by temperature variance.