6875 Freezer/Mill
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SPEX® SamplePrep LLC
DEC 2015
1.0 INTRODUCTION
SPEX SamplePrep Freezer/Mills are laboratory mills that cool unconventional materials to
cryogenic temperatures and pulverize them to a powder form without thermal degradation. Our
proven technology uses a dual electromagnetic, grinding chamber that rapidly drives a steel
impactor back and forth against the two end plugs of the sample vial. Since the vial is securely
closed the integrity of its contents is maintained, hazardous or critical samples are easily
controlled, and cross-sample contamination is eliminated. The sample chemical composition is
preserved as a result of the vials being immersed in liquid nitrogen at cryogenic temperatures
throughout the grinding process. These unique aspects have made SPEX SamplePrep
Freezer/Mills the most effective cryogenic mills in the world. They are the “mills of first choice”
for many abnormal materials, or samples whose composition or structure cannot be ground using
conventional grinding methods.
NOTE: Please do not operate the 6875 Freezer/Mill® until you have read these instructions and
are familiar with its controls and operation. The Freezer/Mill is different in its principles
and operation from any other laboratory mill.
OPERATING CONDITIONS:
Do not set up the 6875 Freezer/Mill® in an insulated or confined space.
The Freezer/Mill should be run on an open countertop, in ambient air, with recommended
maximum relative room humidity 70% from 5°C - 31°C (40°F - 88°F). If the entire mill is chilled
during operation, components such as the gas cylinders, controller, and display screen can fail.
This damage is not covered by the Freezer/Mill warranty. During operation, water vapor in the air
will condense on parts of the unit. For this reason, it is important not to place any moisture-
sensitive equipment near the Freezer/Mill.
VERY IMPORTANT:
Liquid nitrogen not only makes samples brittle through severe chilling, making
them “grindable,” but also cools the magnetic coil which powers the 6875 Freezer/Mill. If the mill
is operated without liquid nitrogen for a period of about one minute, the coil will become very hot
and may sustain permanent damage. The 6875 Freezer/Mill has a liquid nitrogen sensor that
should shut down the mill when the liquid nitrogen gets too low to cool the coil. Nevertheless the
nitrogen level should be visually checked during extended runs as well as topped off before every
run. The Freezer/Mill warranty does not cover damage to the coil caused by operating the mill
with little or no liquid nitrogen.
SAFETY
: Liquid nitrogen (LN) can be hazardous. Its boiling point is -195.8°C (-320.4°F). When
working with liquid nitrogen directly or indirectly, the LN Tank valve or hose, or chilled
Freezer/Mill components, cryogenic gloves must be worn to protect hands. Safety googles are
also recommend to protect eyes from possible splashing. Be careful not to splash liquid nitrogen
onto clothes or unprotected skin. Additional information on LN safety can be found at
http://engineering.dartmouth.edu/microengineering/ln2.html