PerkinElmer Photovac MicroFID, User Manual

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Detailed Operation
Calibration
General Information
MicroFID must be calibrated in order to display concentration in
ppm units equivalent to the calibration gas. First a supply of zero
air, which contains no ionizable gases or vapors, is used to set
MicroFID’s zero point. Then, calibration gas, containing a known
concentration of an ionizable gas or vapor, is used to set the
sensitivity.
Occasionally clean ambient air will be suitable as zero air. Due to
MicroFID’s sensitivity, outdoor air is usually unsuitable for
calibration. A charcoal filter (Part No. MX396021, MX396022)
may be connected to the instrument to produce clean air from
otherwise unsuitable ambient air. For best results, use a commercial
source of zero grade air and a second sampling bag. Zero air should
have not more than 0.1 ppm total hydrocarbons (THC).
Methane in air is recommended as span gas. The concentration of
the calibration gas will depend on your application. When ordering
calibration gas, specify methane in hydrocarbon free air. Balance air
should have not more than 0.1 ppm total hydrocarbons (THC).
Method 21 protocol requires that commercial cylinders of
calibration gas be analyzed and certified to be /­ 2%
accuracy and that a shelf life must be specified on the cylinder. At
the end of the shelf life, the cylinder must be replaced or re­
analyzed.
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