Allied Telesis 6870 Manual Do Utilizador

Page 3 of 25                               SPEX SamplePrep LLC                                        9.24.07                        

 
SECTION 1.0:  INTRODUCTION 
 
SPEX SamplePrep Freezer/Mills are cryogenic laboratory mills that cool samples to cryogenic 
temperatures, and pulverize them by magnetically shuttling a steel impactor back and forth 
against two stationary end plugs. Since the vial is closed, the integrity of its contents is 
maintained: hazardous or critical samples are easily controlled, cleanup is simplified, and cross-
sample contamination is eliminated. Because the vial is immersed in liquid nitrogen throughout 
the grinding cycle, the sample is kept at cryogenic temperatures and its key aspects preserved. 
These features have made SPEX SamplePrep Freezer/Mills the most effective cryogenic mills in 
the world.  They are the “mills of last resort” for many normally ungrindable samples, or samples 
whose composition or structure is altered by the heat generated by conventional grinding. 
 
Before operating the 6870 Freezer/Mill, familiarize yourself with these instructions.  The 
Freezer/Mill is different in its principles and operation from any other laboratory mill. If 
you’re familiar with the mill and want to proceed directly to grinding, Section 6.0 
(PRACTICAL OPERATION) on p.14 can serve as a general review of the actual operation of 
the mill. We suggest unpacking the mill, then going over its various features with these 
instructions in hand before attempting to add liquid nitrogen or grind a sample. 
 
OPERATING CONDITIONS:  Do not set up the 6870 Freezer/Mill in an insulated or confined 
space.  The Freezer/Mill should be run on an open countertop, in ambient air. If the entire mill is 
chilled during operation, components like the gas cylinders can fail.  This damage is not covered 
by the Freezer/Mill warranty.  
 
VERY IMPORTANT:  Liquid nitrogen not only makes samples brittle through severe chilling, 
making them “grindable,” but also cools the magnetic coil which powers the 6870 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 6870 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 NOTES: 
1) Liquid Nitrogen can be hazardous.  Its boiling point is -195.8

nitrogen directly or indirectly, you must wear cryogenic gloves to protect your hands.  Be careful 
not to splash liquid nitrogen on clothes or unprotected skin.  Always use cryogenic gloves when 
handling very cold objects or materials: sample vials, the nitrogen tank valve or hose, chilled 
Freezer/Mill components, etc. We also recommend safety goggles to protect your eyes. 
 
2) Do not attempt to operate the 6870 Freezer/Mill without liquid nitrogen