Precision Thermal‐Conductivity Gas Analyzer Using Thermistors
作者:
R. E. Walker,
A. A. Westenberg,
期刊:
Review of Scientific Instruments
(AIP Available online 1957)
卷期:
Volume 28,
issue 10
页码: 789-792
ISSN:0034-6748
年代: 1957
DOI:10.1063/1.1715724
出版商: AIP
数据来源: AIP
摘要:
The characteristics of a thermal‐conductivity gas‐analyzer unit employing thermistors as sensing elements are analyzed theoretically. It is shown that, as a consequence of the fact that thermistors have a negative temperature coefficient of resistance, the sensitivity of the instrument as a function of bridge current exhibits a maximum. The dependence of zero stability on current and cell temperature is approximately related to differences in resistance, temperature coefficient of resistance, and geometry of the reference and sample thermistors. An apparatus suitable for precise trace analyses is described and results obtained with it are presented. It is suggested that the widespread lack of faith in the inherent stability of thermistors for analysis applications is not justified, and has probably been due to insufficient care with current and temperature control.
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