Retsch Mixer Mill MM 500 control, Руководство пользователя

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The Mixer Mill MM 500 control
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Fig. 11: Operating the MM 500 control with the cryoPad
PLEASE NOTE: The connection of the cryoPad to the MM 500 control is described in the
operating instructions for the cryoPad.
3.4.2 System overview MM 500 control and cryoPad
The cryoPad enables the controlled supply of liquid nitrogen LN
2
and thus represents the link
between the MM 500 control and a storage tank for liquid nitrogen LN
2
. The cryoPad is an
additional device on which the MM 500 control can be set up in a space-saving manner, which
expands the functionality of the MM 500 control by embrittlement and targeted temperature
control in the negative temperature range. The device is connected to the inflow and return
ducts of the two thermal plates via four connections. By selectively cycling the nitrogen flow, the
cryoPad enables the temperatures of the right and left thermal plate of the MM 500 control to be
controlled within narrow temperature limits. In this regard, the cryoPad takes over the exact
control with the help of a PID controller and enables
the parameter “temperature” to be kept
approximately constant depending on the process conditions. In addition to temperature control,
the cryoPad performs elementary safety functions which are necessary when working with liquid
nitrogen. The cryoPad has a RS232 communication line to the mill MM 500 control and is thus
able to take commands from the mill. In operation with the cryoPad, the liquid channels form an
“open hydraulic system”, excess nitrogen evaporates at the device outlet (“Exhaust”) and is
released into the environment.