American Magnetics 110 Liquid Helium Level Meter (CE-Marked) - Manual (Page 11)

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1 Introduction
1.1 Model 110A Features
The American Magnetics, Inc. (AMI) Model 110A Liquid Helium Level
Monitor is an economical level meter designed for systems requiring a
basic liquid helium level readout.
The Model 110A is designed to be used in conjunction with an AMI liquid
helium level sensor. The liquid helium level sensor consists of a small
diameter NbTi filament in a hollow tube. A constant current is passed
through this filament causing the portion of the filament in helium gas to
become resistive, while the portion in the liquid helium remains
superconducting. The resulting voltage across the resistive portion of the
filament is read by the instrument, converted to a liquid level, and
displayed on the front panel meter.
1.1.1 Convenient display
The Model 110A is equipped with an analog display which provides liquid
helium level indication in percent.
1.1.2 Remote monitoring
The Model 110A is provided with a 0-10 VDC (or 0-100 millivolt DC)
recorder output. A 4-20 mA current loop option is available in lieu of the
recorder output.