American Magnetics 150A Portable Liquid Helium Level Meter (CE-Marked) - Manual

1 March 6, 2001
INSTALLATION, OPERATION AND MAINTENANCE
INSTRUCTIONS FOR THE AMI
MODEL 150A
LIQUID HELIUM LEVEL METER
I. INTRODUCTION
The American Magnetics, Inc. (AMI) Model 150A is a compact, fully portable Liquid Helium
Level Meter providing simple and easy operation. The instrument is battery operated and when
used in conjunction with an AMI LHe Level Sensor, provides a truly portable means of
measuring liquid helium levels at any location. The sensor connects to the instrument via a
standard DB9 connector. The instrument displays 0-100% of sensor maximum active length
immersed in LHe. The instrument can be used with AMI sensors with active lengths of up to 60
inches. The instrument is powered by sealed lead-acid batteries. A standard AC-DC adapter
(either 120VAC or 230VAC) is supplied with the unit for charging the batteries. Since battery
energy consumption is strongly dependent on the LHe level being measured, AMI has developed
a special "battery saver" circuit which reduces the power drain from the batteries as more of the
sensor becomes superconducting. Power requirements decrease as LHe level increases. A front
panel POWER LED is provided to indicate sufficient battery power exists to make an accurate
level reading.
II. SPECIFICATIONS (at 25 °C unless stated otherwise)
Input Power (instrument) Sealed lead-acid battery (6VDC)
Input Power (AC adapter) 90VAC to 132VAC 50/60 Hz, or 180VAC to 264VAC
50/60 Hz (depending on specified AC adapter model)
Operating temperature (instrument) 0 to 50 °C non-condensing
Operating temperature (AC adapter) 0 to 40 °C non-condensing
Sensor active length range 1 inch to 60 inches
Linearity 0.5% of full scale
Absolute Calibration 0.5% of full scale
2% of full scale (from 0 to 50 ºC)
Probe Current 75 mA nominal
Battery Life Typically 1,000 readings with a 60" sensor.