Specifications

Heated Flame Ionization Detector Analyzer Module
Rosemount Analytical NGA 2000
748414-A
August 1999
3
INTRODUCTION
1
1.4 THEORY OF TECHNOLOGY
This Analyzer Module uses the flame ionization method of detection. The sensor is a burner
in which a regulated flow of sample gas passes through a flame sustained by regulated
flows of a fuel gas (a hydrogen/diluent mixture) and air.
Within the flame, the hydrocarbon components of the sample stream undergo a complex
ionization that produces electrons and positive ions. Polarized electrodes collect these ions,
causing current to flow through an electronic measuring circuit.
The ionization current is proportional to the rate at which carbon atoms enter the burner,
and is therefore a measure of the concentration of hydrocarbons in the sample. This
measure of concentration is placed on the network, where it can be shown on a data
acquisition device.
F
IGURE
1-1. F
LAME
I
ONIZATION
D
ETECTION
T
ECHNOLOGY
C
Positive
Carbon
Ions
Si
g
nal Conditionin
g
Negative Ion
Collection Plate
Sample
Air
Fuel
+90V