INFICON DataFID Portable Flame Ionization Detector for Leak Detection and Repair (LDAR) - Manual (Page 16)

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Figure 2. Block Diagram
Detector Response
The DataFID is strictly an organic compound detector. It does not respond to inorganic compounds. The
DataFID
’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 DataFID response. Organic fuels (acetylene, refined
petroleum products), burn easily and are also extremely well detected.
The presence of substituted functional groups (amino, hydroxyl, halogens) on a simple hydrocarbon
reduces its combustion efficiency and thus DataFID
’s sensitivity to the compounds methanol and
chloromethane, for example, are detectable with the DataFID but not as well as methane. A greater
number of carbon atoms can offset this loss of sensitivity due to substitution. For example, the DataFID is
more sensitive to n-butanol than it is to methanol.
NOTE: The FID Response Factors Technical Note is maintained on INFICON ’s web site:
www.inficon.com .
Display and
I/O Connector
Keypad
Microprocessor
Power
Supply
Electrical Connections Sample Flow
Pump
Sample
In
Inlet
Filter
Flame Ionization
Detector
Detector
Out