Calibration and linearity verification of capacitance type cryo level indicators using cryogenically multiplexed diode array

Karunanithi, R and Jacob, S and Gour, Abhay Singh and Das, M and Nadig, DS and Prasad, MVN (2011) Calibration and linearity verification of capacitance type cryo level indicators using cryogenically multiplexed diode array. In: Advances in Cryogenic Engineering: Transactions of the Cryogenic Engineering Conference - CEC, 13–17 June 2011, Spokane, Washington, USA, pp. 499-506.

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Abstract

In space application the precision level measurement of cryogenic liquids in the storage tanks is done using triple redundant capacitance level sensor, for control and safety point of view. The linearity of each sensor element depends upon the cylindricity and concentricity of the internal and external electrodes. The complexity of calibrating all sensors together has been addressed by two step calibration methodology which has been developed and used for the calibration of six capacitance sensors. All calibrations are done using Liquid Nitrogen (LN2) as a cryogenic fluid. In the first step of calibration, one of the elements of Liquid Hydrogen (LH2) level sensor is calibrated using 700mm eleven point discrete diode array. Four wire method has been used for the diode array. Thus a linearity curve for a single element of LH2 is obtained. In second step of calibration, using the equation thus obtained for the above sensor, it is considered as a reference for calibrating remaining elements of the same LH2 sensor and other level sensor (either Liquid Oxygen (LOX) or LH2). The elimination of stray capacitance for the capacitance level probes has been attempted. The automatic data logging of capacitance values through GPIB is done using LabVIEW 8.5.

Item Type:	Conference Proceedings
Series.:	AIP Conference Proceedings
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Keywords:	Calibration; Diode array; Capacitance; Level; Data Acquisition (DAQ); Stray Capacitance
Department/Centre:	Division of Physical & Mathematical Sciences > Centre for Cryogenic Technology
Date Deposited:	04 Mar 2013 08:49
Last Modified:	05 Mar 2013 07:01
URI:	http://eprints.iisc.ac.in/id/eprint/45408

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