We had good luck with a similar construction project where we simply built a
protective box around the magnet. We needed to replace a large metal fume
hood and tear out some masonry about 2 meters away from our unshielded
400/89, along with some ductwork directly above the magnet. We built a
sturdy box out of thick plywood, surrounding the magnet on 3 sides and on
top. The box was barely bigger than the magnet, and our craftsmen assembled
it carefully, working very close to the magnet. The box was anchored to
keep it from sliding. We topped off the liquid helium before building the
box, and we filled liquid nitrogen through the open side during the
construction. When we weren't filling, the open side (which faced away from
the construction area) was covered with a plastic curtain. Construction was
completed and the box removed before another liquid helium fill was needed.
Steve McKenna
BP, Naperville, IL
mckennst_at_bp.com
+1 (630) 961-7846
Received on Tue Aug 06 2002 - 15:10:05 MST