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Browse Prior Art Database

Liquid Nitrogen Level Sensor

IP.com Disclosure Number: IPCOM000090238D
Original Publication Date: 1969-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR

Abstract

This ferromagnetic temperature sensor determines the level of liquid nitrogen in a container. Its Curie temperature Tc is near 85 degrees K and it has windings for excitation. The small EuO core, drawings A and B, is doped with Eu. For detecting the nitrogen level the sensor is placed some distance above the desired level. When the liquid level drops and the temperature of the sensor rises several degrees, the magnetization M of the sensor becomes zero as shown in drawing C. This critical change in M is utilized for the liquid nitrogen level sensor. The sensor of the drawing A consists of a small transformer with an EuO core and fifty turns of AWG 40 wire as primary and secondary windings. For temperatures below Tc, the induced voltage in the secondary winding energizes the sensitive relay so that the relay is open.

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Liquid Nitrogen Level Sensor

This ferromagnetic temperature sensor determines the level of liquid nitrogen in a container. Its Curie temperature Tc is near 85 degrees K and it has windings for excitation. The small EuO core, drawings A and B, is doped with Eu. For detecting the nitrogen level the sensor is placed some distance above the desired level. When the liquid level drops and the temperature of the sensor rises several degrees, the magnetization M of the sensor becomes zero as shown in drawing C. This critical change in M is utilized for the liquid nitrogen level sensor. The sensor of the drawing A consists of a small transformer with an EuO core and fifty turns of AWG 40 wire as primary and secondary windings. For temperatures below Tc, the induced voltage in the secondary winding energizes the sensitive relay so that the relay is open. When the temperature exceeds Tc, the relay closes and the timer actuates the electrical valve for a preset period for filling of the liquid nitrogen container. In drawing B the EuO sensor is used as a choke. For temperatures above Tc, the impedance of the coil becomes almost zero and the relay is activated which turns on the timer.

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