Advantages of permeation devices
Disadvantages of bottled standards
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Use pure substance in an inert matrix
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Precise concentrations
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Easily generated with NIST traceablity using
established EPA and ASTM protocols
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Removal and/or addition of a single component
is simple
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Wide range of concentrations easily generated
by varying the dilution flow rate and/or the set
point temperature
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Expensive
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Balanced in another medium
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Large number of gas cylinders needed for
calibrations requiring multiple components over
a wide range of concentrations
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Consume valuable lab space
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Possible degradation of standard with the
cylinder
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Mutually reactive chemicals cannot be used
Summary
Calibration devices from VICI Metronics offer several advantages over cylinder-supplied gas
calibration standards. Multi-component gas mixtures can be easily generated with NIST
traceability using established EPA and ASTM protocols by using the appropriate combination
of permeation devices. The technique also allows the removal of a single component from a
gas mixture by simply removing the appropriate permeation device. A wide range of
concentrations can easily be generated by simply varying either the dilution flow rate and/or
the set point temperature.
By contrast, bottled trace level (ppb and ppm) standards can be very expensive, and
calibrations requiring multiple components over a wide range of concentrations require a
large number of gas cylinders, consuming valuable lab space as well. Problems can also
arise from degradation of the standard within the cylinder, from changes in the
concentration levels as the cylinder pressure changes, and from interaction of calibration
components and surfaces.
Permeation Devices vs. Bottled Trace Level Standards
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