6
Sample Stirrer
The sample stirrer is a plate containing electromagnetic coils positioned beneath the instrument cavity floor. The
electromagnetic stirring plate works in conjunction with stirring bars placed in the reaction vessel to affect stirring and
ensure a homogeneous sample. An initial supply of magnetic stir bars are provided with the system. Additional stir bars are
available from CEM Corporation. Commercial Teflon® coated magnetic stir bars can be used.
NOTE: The stir bars are Teflon®-coated iron oxide bars. When placed in the microwave field, the iron oxide bars will reflect
the microwave energy without damaging the instrument.
WARNING
Cardiac pacemakers require magnets to control operation during checkout. If the Discover System is equipped with a
sample stirrer, some danger exists if a pacemaker is positioned in close proximity to the instrument cavity. If the
instrument is suspected of interfering with the operation of a pacemaker, the instrument should be turned off or the
pacemaker wearer should move away from the instrument.
Cooling
The cooling feature directs a gas source onto the outside wall of the reaction vessel. This provides the ability to rapidly
cool (quench) a reaction after the application of microwave energy. The cooling feature is either on or off and is part
of the method. The feature consists of:
• plumbing to direct the gas from the inlet point of the Discover to the reaction vessel in the cavity, a solenoid
valve connected to the CPU (controller) board to turn the gas flow on and off,
• A hose fitting to connect the Discover to the gas source via hose, and
• 8 feet (2.44 meters) of 1/4 inch (6.35 mm) inside diameter air hose.
The gas source is user supplied. CEM Corporation recommends either nitrogen or clean air at a minimum pressure of 25 psi
(~ 1.5 bar). This will provide a flow rate of 20 liters per minute and will cool a 5mL volume of ethylene glycol in a 10mL reaction
vessel from 150°C to less than 50°C in less than 2 minutes.
To Next Page
Loading...
Need help?
General
