American Magnetics 4Q06125PS-430 High Stability Integrated Power Supply System - Manual (Page 16)

xvi Rev. 5
Foreword
Safety Summary
is 18-8 stainless steel. Copper, Monel
®
, brass and aluminum are also
considered satisfactory materials for cryogenic service.
Magnet Quenches
When an energized superconducting magnet transitions from
superconducting state to normal state, the magnet converts magnetic
energy to thermal energy thereby rapidly converting the liquid helium to a
vapor. When this phase transformation occurs, pressures can build rapidly
in the cryostat due to the fact that one part of liquid helium will generate
782 parts of gaseous helium at STP (standard temperature and pressure).
The cryostat must be designed to allow the generated vapor to rapidly and
safely vent to an area of lower pressure. Cryostats are designed with
pressure relief valves of sufficient capacity so as to limit the pressure
transients within the container in order to prevent damage to the vessel.
Operating a superconducting magnet in a cryostat without properly sized
relief mechanisms or disabled relief mechanism is unsafe for the operator
as well as for the equipment. If there is any doubt as to the sufficiency of
the pressure relief system, contact the manufacturer of the magnet and
cryostat for assistance.
Safety Summary
Superconducting magnet systems are complex systems with the potential
to seriously injure personnel or equipment if not operated according to
procedures. The use of cryogenic liquids in these systems is only one factor
to consider in safe and proper magnet system operation. Proper use of
safety mechanisms (pressure relief valves, rupture disks, etc.) included in
the cryostat and top plate assembly are necessary. Furthermore, an
understanding of the physics of the magnet system is needed to allow the
operator to properly control the large amounts of energy stored in the
magnetic field of the superconducting coil. The Model 430 Programmer has
been designed with safety interlocks to assist the operator in safe
operation, but these designed-in features cannot replace an operator’s
understanding of the system to ensure the system is operated in a safe and
deliberate manner.
Recommended Safety Equipment
• First Aid kit
• Fire extinguisher rated for class C fires
• Cryogenic gloves
• Face shield
• Signs to indicate that there are potentially damaging magnetic fields
in the area and that cryogens are in use in the area.