INFICON MicroFID II Portable Flame Ionization Detector - Manual (Page 59)

074-579-P1A 59
Methane in air is recommended as span gas. However, Hexane or Propane can also be used
as span gas. The choice is made from the Calibration Menu
– Select Span Gas. The
concentration of the calibration gas will depend on the application. When ordering calibration
gas, specify methane or any compound to be calibrated with in hydrocarbon free air. Balance air
should have not more than 0.1 ppm total hydrocarbons (THC).
NOTE: Method 21 protocol requires that commercial cylinders of calibration gas be analyzed
and certified to be within +/- 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.
NOTE: It is advisable to allow the unit to warm for at least 20 minutes before calibrating to
insure accurate calibration.
Calibration Accessories and Preparing for Calibration
It is best to prepare the accessories and the necessary equipment before the user will calibrate.
Following the procedures outlined here will make the actual calibration step easier for the user.
Calibration Techniques
There are two techniques to calibrate a MicroFID II:

Direct connection of the calibration gas to the MicroFID II through a flow match regulator,
which is the preferred technique and provides good accuracy

Fill a Tedlar bag with the calibration gas and then connect the bag to the MicroFID II, which
is less preferred due to potential error introduced when the bag is pushed or squeezed.
These two connection techniques will be discussed followed by the general calibration
procedure.
Connecting the MicroFID II with the Flow-Match Regulator
1. Ensure the MicroFID II and the calibration gas cylinder is in the upright position.
2. Connect the regulator to the calibration gas cylinder.
3. If a portable tank of 500 ppm methane calibration gas (Part No. MX396028) is used,
connect the regulator (Part No. MX704210) directly to the tank. Other calibration gas
compounds and concentrations can be used as necessary.
4. When the regulator is connected properly, the cylinder pressure can be read from the
regulator gauge.
5. Connect the adapter tubing to the regulator, and connect the other end of the tubing to
the MicroFID II inlet.