Electron Capture Detector (Ecd) Theory Of Operation; Epc Detector; Manually Controlled Detector - Agilent Technologies 6890 Series Service Manual

340 Electron Capture Detector (ECD)
Theory of operation

EPC detector

The EPC version of the ECD detector has one flow line for the anode purge/
makeup gas. After an initial filter frit, it splits into two paths. Each line has
a proportional valve controlled by a pressure sensor, and a non-adjustable
restrictor frit. The makeup gas line sweeps past the end of the column and
carries the column effluent into the ECD cell. The anode purge flow sweeps
the upper part of the ECD and cleans sample deposition from the detector.
Anode
purge and
makeup gas
in
Figure 340-2

Manually controlled detector

The manually controlled ECD has a pneumatic supply line for the anode purge
gas and for the makeup gas. Both lines have an on/off solenoid valve and a
nonadjustable restrictor frit. A pressure regulator allows for adjusting the
2 of 24
Pressure
Filter Proportional
sensors
valves
frit
PS
Makeup
PS
Pressure
control loops
EPC ECD flow diagram
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Restrictors
Anode
Vent
purge
63
Ni plating
Capillary adapter
Jun 2001