69
GC Injectors
AutomatedCalibrationSystem (ACS)
For theSRI TO-14AirMonitoringGC
TheSRI AutomaticCalibrationSystem (ACS) allows for automatic, unattended recalibrationwhen using an
SRI GC equippedwith the TO-14Air Concentrator for ambient air analysis.
100ppm
standard gas
cylinder and
regulator,
customer
supplied
Sample introduction “T”
through which vacuum
pump pulls either gas
standard or ambient air
Zero air
cylinder and
regulator,
customer
supplied
EPC inGC
(PeakSimple
control)
SolenoidA
(PeakSimple
control)
SolenoidB
(PeakSimple
control)
Restrictor
0-100mL/min
(determined
byEPC
pressure)
Restrictor
1000mL/min
fixed flow
10psi
Mixing
chamber
Flow through TO-14
GCtrap=100mL/min
Vacuumpump
(PeakSimple control)
Undercontrolof thePeakSimplesoftware includedwith theGC, theACScanmakedilutionsof thecustomer-
supplied standardgas andZeroAir at ratios of 10,000 to1. For example, if the standardEPCon theTO-14
GC is set to50psi, a100ppm standardgaslows through the restrictor at a rateof 100millilitersperminute;
the Zero Air lows at a rate of 1,000 milliliters per minute. This produces a 10ppm diluted gas, which is
sampled into the TO-14Air Concentrator by the vacuumpump (suppliedwith the TO-14Air Concentrator).
Bymanipulating both the EPC pressure and time, the 100ppm standard can be diluted over a 10,000 to 1
concentration. For example, let’s say you’vedecided touse 300 seconds as the lengthof time the vacuum
pump issampling thestandardgas. If thestandardEPCpressure is reduced to10psi, thestandardgaslow
rate is reduced to 10milliliters perminute, and the resulting diluted concentration is 1ppm. If solenoidA is
open for 30 seconds (10% of the total 300 second time period during which the vacuum pump is pulling
sample through theTO-14 trap), the resulting time-averagedconcentration is100ppb.BecausePeakSimple
controls the dilution ratio, a multi-point calibration curve can be automatically constructed as part of the
AutosamplerQueue feature. TheAutosamplerQueuepermitsPeakSimple toperiodically recalibratewithout
operator intervention.
8640-0050
TO-14AutomaticCalibrationSystem
