PerkinElmer Photovac MicroFID, User Manual

Page: 139 / 170

Technical Description
The ions move in the electric field, generating a current, which is
proportional to the concentration of the ionized molecules in the
ionization chamber. An electrometer circuit converts the current to a
voltage that is then fed to the microprocessor.
After the sample passes through the flame and has become ionized
it is vented from the detector through a flame arrestor. The flame
arrestor prevents the flame from igniting any flammable gases
present in the sampling location.
Display and
I/O Connector
Keypad
Microprocessor
Power
Supply
Electrical Connections
Sample Flow
Pump
Sample
In
Inlet
Filter
Flame Ionization
Detector
Detector
Out
Figure 28 Block Diagram
Detector Response
MicroFID is strictly an organic compound detector. It does not
respond to inorganic compounds. MicroFID’ s sensitivity is highly
dependent on chemical structure and bonding characteristics. The
combustion efficiency of a compound determines its sensitivity.
Simple saturated hydrocarbons (methane, ethane etc.) possess high
combustion efficiencies and are among the compounds that produce
the highest MicroFID response. Organic fuels (acetylene, refined
petroleum products), burn easily and are also extremely well
detected.
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