User guide

Inlets 8
Advanced User Guide 257
About the VI split mode
When you introduce a sample in the split mode, a small amount
of the sample enters the column while the major portion exits
from the split vent. The ratio of split flow to column flow is
controlled by the user. The split mode is primarily used for high
concentration samples when you can afford to lose most of the
sample out the split vent and for samples that cannot be diluted.
Split ratio
Because of the interface’s small internal volume, the maximum
total flow to the interface is 100 mL/min. This maximum flow
puts some restriction on the split ratio you can set.
Split mode pneumatics
During Pre Run, during sampling, and after sampling, total flow
to the interface is measured by a flow sensor and controlled by
a proportional valve. Flow at the head of the column is
back- pressure regulated. Pressure is sensed upstream from the
proportional valve.
Recommended temperature: ≥ transfer line temperature of the
external sampling device
Table 52 Specifications of the volatiles interface (continued)
Specification Value/Comment
Table 53 Maximum split ratios
Column diameter
(mm)
Column flow
(mL/min)
Maximum split
ratio
Total fl ow
(mL/min)
0.20 1 100:1 100
0.53 5 20:1 100