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Page 7 of 25 SPEX SamplePrep LLC 9.24.07
The control panel is a touch-screen, activated by a stylus. The Freezer/Mill is programmed and
operated through this control panel, whose successive screens are described and illustrated in
Section 5, starting on page 8. Programmable parameters include pre-cooling time, grinding time,
cooling time between grinding periods, the number of grinding periods, and the rate of grinding.
The control display also warns if the lid is not fully closed, or if there is not enough liquid
nitrogen in the tub.
4.3 Lid and Lid Latch, Coil Assembly and Coil Gate, LN Sensor
The lid of the 6870 Freezer/Mill supports the coil (dual electromagnet assembly) and coil
housing. To open the lid, hold the lid down with one hand, and with the other pull the upper end
of the latch toward you. The lower end of the latch should disengage from the cabinet. Release
the lid and it should be pushed up by the gas cylinders, which also keep the lid raised when open.
The lid must be open to put vials in the coil and take them out. Liquid nitrogen (LN) is added
with the lid open, unless the 6870 is equipped with the 6820 Auto-Fill System.
The lid must be shut and latched for the Freezer/Mill to run. Push the lid down, hold it down
while engaging the latch, then lock the latch by pushing its top end toward the cabinet.
The circular hole on the right side of the coil housing is where to insert a vial for grinding. The
coil gate keeps the vial or vials in place during grinding, but must be lowered to insert or remove
vials. The rectangular space toward the top of the coil housing is for pre-cooling loaded vials.
(Do not run the 6870 Freezer/Mill without a loaded vial in the coil.)
The coil gate holds the vial or vials in the coil during grinding. To lock a vial in place, loosen
(unscrew) the coil gate handle a turn or two, and position it so the handle passes through the slot
in the coil gate when the gate is raised. Tighten the coil gate handle against the gate, so the gate
contacts the vial snugly, but do not overtighten the gate as this can crack the plastic center
section of the vial. When the coil gate handle is properly tightened, fold it down to lock the gate
during grinding. Always use the proper Adapters for Mid-Size and Small vials (see 4.4), and
always wear gloves when touching a chilled vial or any part of the chilled coil housing!
The LN sensor is behind a shield on the back wall of the LN tub. If there is not enough liquid
nitrogen in the tub to start the mill, when RUN is touched the STATUS screen (p. 10) will display
STATUS: LOW LN LEVEL. If the LN runs low during a grinding program the same message
will appear and the program will stop. To continue running, fill the tub with liquid nitrogen to
the mark. When RUN is pressed, the grinding program will start over.
To keep a run from being interrupted by the liquid nitrogen (LN) sensor, the LN level should
be visually checked from time to time during extended runs, as well as before every run. The
6870 Freezer/Mill can run low on LN during extended runs, so should be checked after each
30 minutes of grinding time, and the LN topped off if necessary. The Freezer/Mill warranty
does not cover damage to the coil caused by operating the mill with little or no liquid nitrogen.