Topic: __
.-
EPC(E'llect~~nicp_re~sure
control) operation
.
" rcCCC;;c _ .
._
SRI GCs are equipped with electronic pressure control of all
system gases. Detector support gases such as hydrogen and air
are controlled by the screwdriver adjustable local setpoint on the
GC, and once set are seldomaltered. The carrier gas pressure
may
be
controlled by either the local setpoint screwdriver adjust–
ment or by the channel
two
pressure program in the PeakSimpte
data systemsoftware. The main benefit of carrier gas pres–
sure programming ( ramping ) is to speed up the flow rate
through the column at the end of the run in order to elute
high boiling peaks more quickty.
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l ocal setpoint adjustments for
temperatures and pressures using
small screwdriver
_
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Set the 'Control By" radiobut–
ton in theChannel 2Details
screen to Pressure.
Then enter thedesiredpres–
sureprogram intoChannel 2
by selecting thePressure
screen fromthe
EdillChannel..J~~~~t0~
menu
Most chromatographers choose
to
set the carrier gas pressure
using the screwdriver local seucmt adjustment rather than the
channel
two
pressure program
for
the following reasons :
1)
Thescrewdriveradjustment is simpler. andonce set is
not likely
to
be
altered unintentionally.
2)
The benefitsof ramping the carrier gas pressure are
often not worth the extra operational complexity.
Because very few userschoose toutilize the pressure
proqram–
ming features, all SRI GCs are shipped with the EPC control
disabled. Instructions for enabling the EPCare shown on the
following page. Once theEPC is enabled, the carrier gas pres-
the PeakSimple data system software. Channel two must
be
activated and a pressure programentered even if only a single
detector signal is beingacquired on channel one. The pressure
program end time must be coordinated with the temperature
program for the columnoven
which
is
loaded into channel one.
Manl49.pub
