Manually Controlled Detector - Agilent Technologies 6890 Series Service Manual

Manually controlled detector

The manually controlled NPD has three pneumatic supply lines for air,
hydrogen and makeup gas. All three lines have an on/off solenoid valve and
a non-adjustable restrictor frit. In addition, the makeup gas line has a pressure
regulator to change flow without changing supply pressure. The makeup gas
and hydrogen lines merge before entering the detector.
Makeup in
Figure 320-3
Jun 2001
On/off
solenoid
valves
Air in
H in
2
Pressure
regulator
Manual detector flow
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Nitrogen Phosphorus Detector (NPD)
Theory of operation
Restrictors
320
Vent
Electrically
heated bead
3 of 32