American Magnetics 160 User Manual

INSTALLATION, OPERATION AND MAINTENANCE

INSTRUCTIONS FOR THE AMI

MODEL 160

LIQUID HELIUM LEVEL SUPERCONDUCTING DIPSTICK

I. INTRODUCTION

The American Magnetics, Inc. (AMI) Model 160 Liquid Helium Level Superconducting
Dipstick is designed for measuring the level of liquid helium in storage dewars that are
accessible from the top. The dipstick is a cost effective, low loss, accurate alternative to
flutter tubes and carbon resistor liquid helium level measuring devices.

Each Model 160 consists of a superconducting point sensor mounted on an extension tube
and a detachable electronics enclosure.

II. SPECIFICATIONS

Sensor Diameter ............................... 0.25 Inch

Extension Tube Diameter ...................... 0.25 Inch

Sensor Active Region .......................... 0.1 Inch

Sensor and Extension Tube Overall Length .... 72 Inches

(Custom Lengths may be provided at the customers request.)

Cable Length ................................... 8.5 Feet

Electronics Enclosure Dimensions .............. 2-3/8" W x 4-1/4"L x 1-1/8" H

Total Weight ................................... 12 Ounces

Accuracy .................................... +/- 0.1 Inch

Repeatability ................................... +/- 0.1 Inch

III. INSTALLATION

1. Carefully remove the sensor from the shipping tube and the electronics enclosure from its
packaging material.

NOTE: Save the PVC shipping tube as a handy storage
container and to protect your dipstick from damage when not in
use.

2. Inspect the sensor and electronics enclosure for any physical damage that may have
occurred during shipment.

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NOTE: If there is any shipping damage save all packaging
material and contact the shipper's representative to file a damage
claim. Do not return any damaged material to AMI unless prior
authorization has been received (see Section VIII).

3. Plug the connector at the end of the sensor cable into the mating receptacle located at the
end of the electronics enclosure.

IV. OPERATION

1. Place the toggle switch on the electronics enclosure to the GAS DETECT position. The
green POWER LED should be illuminated indicating that the Model 160 is energized and
battery voltage is sufficient for proper operation. The red ALARM LED should be
illuminated indicating an alarm condition since the dipstick is in a gas (not in liquid
helium). The audible alarm should be sounding indicating an alarm.

2. Place the toggle switch on the electronics enclosure to the LIQUID DETECT position.
The green POWER LED should remain illuminated and the red ALARM LED, along
with the audible alarm, should go out since the dipstick is not in liquid helium.

NOTE: The Model 160 dipstick incorporates an automatic
power indicator shutoff circuit in the event of low battery power.
When the battery has reached a preset voltage level the circuit will
prevent the power LED from lighting up. The unit may still work
with the power LED off, but it is recommended that the battery be
changed at this point.

3. Ensure your helium storage vessel is properly vented and has an access slightly larger
than the sensor. The Model 160 dipstick is designed to use the transfer tube port in a
standard portable helium dewar.

CAUTION: Due to the length and small diameter of the dipstick,
if inserting the dipstick in a close tolerance opening, be careful not
to apply any lateral force to the dipstick to prevent any damage.

WARNING: Always lower the warm dipstick into the storage

container very slowly to ensure that pressure buildup in the
storage container is not excessive. Failure to do so could result in
equipment damage and/or personnel injury.

4. Slowly lower the dipstick until it touches the surface of the liquid helium. The audible
alarm will sound and the red ALARM LED will illuminate. Place the toggle switch to the
GAS DETECT position, the alarms should go out, and continue to lower the dipstick
until it reaches the bottom of the dewar. Mark the tube at a known reference point with a

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