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KU's 800 MHz NMR facility in the Structural Biology Center
800 magnet lab
We designed a suite of four rooms to house our 800 MHz
instrument: a magnet room, console room, computer room, and utility
chase. The largest of these is the magnet room itself, as
pictured above and shown as room 100A in the floor plan below.
This room is a 40' diameter circle that encloses all of the 10 gauss
fringe field and nearly all of the 5 gauss fringe field. The
fringe field lines are shown on the floor--the innermost lighter circle
encloses 10 gauss, the dark circle between 10 and 5 gauss, and the
lighter area beyond it is below 5 gauss. The room has a 16' 6"
ceiling. Underneath the magnet is a 15' square vibration isolated
concrete slab containing no ferromagnetic materials; it is supported by
five concrete piers sunk down to bedrock, about 20 feet
underground. The aluminum access platform was fabricated by
Marcon Metals in Ontario, Canada and assembled around the magnet after
it was set on its antivibration stand. The building's mechanical
systems are also on slabs isolated from the building itself, so the
vibrations transmitted through the building floor are negligible. The
round form of the magnet lab is reflected in the distinctive gray brick
cone on the outside of the building.
Exterior view of the 800 lab
A constant temperature, constant flow air supply enters the
room via the supply vents visible at the top of the picture
above. The air returns through the vents at the lower left,
through the second room in the suite, a utility chase (room
100A1). If oxygen sensors (located at floor and ceiling level,
but not directly above the magnet), detect the oxygen level in the room
has dropped (as would happen in the case of a magnet quench), a large
fan in the ceiling turns on to pull the low-oxygen atmosphere outside,
the building air supply is shut off, and a louver in the utility chase
opens to admit large quantities of air directly from the outside so the
normal air return route becomes the air supply route for the duration
of the emergency. We also have a "panic button" to start
the exhaust fan if the oxygen sensors should ever fail to turn it on
automatically.
Floor plan of the 800 suite
Most of the heat producing equipment (the RF console and the magnet
pumping system) are in the console room (room 100), which is well
supplied with air conditioning. Because there are almost no
sources of heat in the magnet room, the air conditioning there is
not required to cycle on and off, and keeping a
very stable temperature around the magnet becomes much simpler. We
maintain a very constant 70.5 F in the magnet room. With the
number of fans and pumps running in the console room, the
background noise level there is fairly high. For this reason, the
data system (and the operator) are located in a separate computer room
(102), which is much quieter than the console room, and its heat
load is also isolated from the magnet room. We made extensive use
of glass between the rooms and the 800 suite and the lobby, in order to
give visitors a good view of the lab operations.
View of the magnet room through the computer room
The 800 instrument is performing
extremely well in this very stable environment. The level of
engineering and safety systems in this lab far exceeds what we have in
any of our NMR rooms in other buildings on campus.
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