CompactGC manual
30
6.2
Leak
check
A leak check is performed by pressurizing the sealed system with carrier gas. Any leaks
are registered by a drop in the pressure reading. The pneumatic diagram, supplied with
the system, is a useful tool.
TCD channel
•
turn of the bridge temperature
•
turn off the reference gas (send value 0)
•
seal the end of the channel by a 1/16” cap on the detector outlet
•
set the total flow to zero
•
set the inlet pressure to 100 kPa, and after the channel is pressured, set the
pressure to zero
•
observe the pressure
FID channel
Extreme care should be taken to a leak-tight gas connection since hydrogen is used as
FID feeding gas. This feeding gas is mixed with the carrier gas at the end of the column
(see figure 6.2; left nut). In case of a leak, hydrogen will enter the column oven.
For a total check of this channel, the FID detector is disconnected, and the flame jet is
replaced by a blind jet.
•
turn off the hydrogen and air gas supply (send value 0)
•
seal the detector base or the end of the column
•
set the total flow to zero
•
set the inlet pressure to 100 kPa, and after the channel is pressured, set the
pressure to zero
•
observe the pressure
An electronic leakchecker may also be used.
PDD channel
For this channel, except the gas from the digital gas controllers, also discharge gas is
supplied directly via a restrictor (see the PDD, chapter 3.4).
•
turn off the pulser
•
set the total carrier flow to zero
•
set the inlet pressure to 150 kPa, and after the channel is pressurized, set the
pressure to zero
•
close the external gas supply to the CompactGC
•
wait until a stable pressure readout is obtained (approximately 150 kPa), and
observe if this value remains stable