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6. Press the DISCOVER key to activate and program parameters for the ActiVent option. If the ActiVent feature is
not being used, proceed to step 8.
CAUTION
If the reaction temperature exceeds the acid boiling point and too many venting actions are performed, the vial
could become dry and superheat.
NOTE:
The ActiVent feature is not required for the Dynamic Control Option. It allows the Discover SP-D Clinical System
to release unwanted gaseous byproducts from the reaction to prevent over pressurization and vial failure from gaseous
buildup.
NOTE:
If the ActiVent feature is not being used, the system will automatically release excess pressure above 400 Psi or
21 Bar.
7. Enter the desired vent parameters using the ARROW keys to navigate between Delta Pressure, Stage, PressureSp,
and Times @ SP. Use the “+/-” keys to increase and decrease the numeric value(s).
The “Delta Pressure” is the assigned amount of pressure to drop from the pressure set point. A delta of 50 PSI
(1.7 BAR) is recommended.
The “PressureSP” is the pressure set point at which the venting will begin. If the gaseous byproduct that is
generated is the only pressure in the reaction vial (the reaction temperature does NOT exceed the boiling point of
the solvent), the ActiVent pressure release can be set below the control point. If a gas is generated, but some of
the pressure is due to vapor pressure, then the release point for the ActiVent must be set at or above the
pressure control point.
The “Times at SP” is the maximum number of times a reaction will vent during the assigned ramp and hold time.
However, this parameter can be adjusted based on specific reaction conditions. For a typical reaction, 5 vents
are recommended.
The number of stages is the stage at which the PressureSP will be active for a multistage method. A maximum of
5 stages can be added.
8. Once all ActiVent parameters have been entered, press the ENTER key to return to the method parameters screen.
9. Press the ENTER key to accept all method parameters.
Ramp-to-Temperature
The Ramp to Temperature Control option is the RECOMMENDED control type for all digestion samples. The sample is
brought to temperature in an exact programmed time, and power is varied automatically to follow that time. The effects of
variations in sample absorbance characteristics are minimized as each sample runs the same temperature profile. The
user programs:
the ramp time to achieve the temperature
the hold time at that temperature
the input power level
a control temperature (the temperature at which the magnetron will turn off)
a maximum pressure (the maximum pressure the Discover SP-D Clinical will control at or below)
stirring speed (stirring is required for digestions). CEM Corporation recommends medium speed.
a premix time (time for stirring before the heating begins)
