About The Fpd - Agilent Technologies 7890 Series Advanced Operation Manual

5
Detectors

About the FPD

H
2
Frit
Valve
PS
Restrictor
PS = Pressure Sensor
206
The sample burns in a hydrogen- rich flame, where some
species are reduced and excited. The gas flow moves the
excited species to a cooler emission zone above the flame
where they decay and emit light. A narrow bandpass filter
selects light unique to one species, while a shield prevents
intense carbon emission from reaching the photomultiplier
tube (PMT).
The light strikes a photosensitive surface in the PMT where
a light photon knocks loose an electron. The electron is
amplified inside the PMT for an overall gain of up to a
million.
Makeup Air
Frit Frit
Valve Valve
PS
Restrictor
The current from the PMT is amplified and digitized by the
FPD electronics board. The signal is available either as a
digital signal on the communications output or as a voltage
signal on the analog output.
The FPD should not be stored at temperatures above 50 °C,
based on the original manufacturer's specifications for the
PMT.
EPC Module
PS
Restrictor
Column
Vent
Emission Zone
Wavelength filter
Window
Advanced Operation Manual