Operating theSRI AutomaticCalibrationAccessory
( ACS )
If thedesireddilution ratio is higher than canbeachievedby lowering the “cal gas “
EPCpressure, then the timeduringwhich the “ cal gas” solenoid is actuated canbe
controlled fromPeakSimple’sChannel 1Event table. This isonly valid formolecules
which trap completelywithnobreakthroughduring the samplingperiod. For exam-
ple, BTEX traps completely onTenax-GRwithnobreakthrough for a5minute sam-
pling periodwhereas ethylenewould not. Formoleculeswhich do not breakthrough
the trap, the “ cal gas” solenoid canbeactivated for a fractionof the samplingperiod.
In theexampleEvent tablebelow, The “cal gas “ solenoid (RelayAon thisparticular
GC ) isactuatedat 0.2minutesandde-activatedat 3.00minutes. Notice that the
“zero” gas ( RelayC ) flow remains on from0.1 to6.150minutes or until theVacuum
Pump ( RelayD ) turns off. Noticealso that both “zero” and “ cal gas “ are turnedon
twominutes before the vacuumpumpbegins pullinggas through the traps. This is to
allow thegas flows toequilibrateprior to sampling thediluted flow.
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Cal Gas solenoidOn
