About The Npd; Npd Flows And General Information - Agilent Technologies 7820A Advanced User's Manual

About the NPD

NPD flows and general information

H
2
Frit
Valve
PS
Restrictor
PS = Pressure Sensor
Advanced User Guide
We strongly recommend that you allow the firmware to perform
Auto Adjust and set the Bead Voltage.
The NPD passes sample and carrier through a hydrogen/air plasma.
A heated ceramic or glass source, called the bead, is just above the jet.
The low hydrogen/air ratio cannot sustain a flame, minimizing
hydrocarbon ionization, while the alkali ions on the bead surface
facilitate ionization of nitrogen- or phosphorus-organic compounds.
The output current is proportional to the number of ions collected. It
is sensed by an electrometer, converted to digital form, and sent to an
output device.
Makeup Air
Frit Frit
Valve Valve
PS
Restrictor
EPC Module
PS
Restrictor
Column
5
Detectors
Vent
Electrically
heated bead
85