User guide

Inlets 8
Advanced User Guide 245
control the inlet operation. This is discussed in more detail
under “To develop a PTV method that uses large volume
injection” on page 247.
Setting parameters for solvent vent operation
Mode: The current operating mode—solvent vent.
Tem pe ratur e Actual and setpoint initial inlet temperatures.
Initial time The time, measured from Start Run, when the
initial inlet temperature hold ends. Must be greater than Vent
end time.
Rate # Temperature program rate for inlet thermal ramps.
Final temperature # Final inlet temperature for ramps 1, 2, and
3.
Final time # Hold time at Final temp #. This time is a duration; it
is not measured from Start Run.
Pressure Actual and setpoint inlet pressure before and after
the vent period. It sets the starting point of column head
pressure.
Vent pressure The inlet pressure during the vent period. By
decreasing the inlet pressure while venting, solvent elimination
proceeds faster. Also, the pressure reduction decreases the
amount of carrier gas—and solvent vapor—that enters the
column during this time.
Users select from 0 to 100 psig. If 0 is chosen, the inlet uses the
lowest pressure possible at the given vent flow. Table 45
shows
approximate values for this minimum at various vent flows of
helium. Pressures less than those in the table are not possible
unless the flow is reduced.
Table 45 Minimum attainable pressures
Vent flow (mL/min) Actual vent pressure at
“0“ psig setpoint
Actual vent pressure at
“0” kPa setpoint
50 0.7 5
100 1.3 10
200 2.6 18
500 6.4 44