INFICON 2020ComboPRO Portable Photoionization Detector - Manual (Page 67)

60 ISP-074-575-P1D 60
collection is conducted utilizing the optional INFICON Tube Holder (A1790500)
and sample collection tubes. On selection of SAMPLE MODE from the UNIT SET
UP menu, the pump will shut off and the user will be instructed to ATTACH TUBE
HOLDER and INSERT NEW TUBE. Next, set the sample volume in The
SAMPLE soft key will activate the pump for a short period of time drawing ambient
air into the SAMPLE TUBE. When finished, the user will be prompted to either
continue sampling or return the 2020ComboPRO to normal operating mode.
Menu
Unit Setup
Pump
Backlight
User Mode
Clock
Date Format
Language
Units
Sample Collection
Enter sample liters
Attach tube holder and
insert new tube
Press ‘Next’ to continue
Collecting sample
Sample Completed
Collect more samples?
Detach tube holder and
remove tube
Press ‘Next’ to continue
NO
YES
Figure 19. Sample Collection Mode
Response Factor Library
The response of a compound to a PID is dependent on its ionization potential. In
certain situations when the user is confident that only a single specific compound
exists, they can set up the 2020ComboPRO using an isobutylene calibration to
mimic the 2020ComboPRO response as if the 2020ComboPRO was calibrated using
that specific single compound.
General Information
In situations where only a single pure compound is present in air, the
2020ComboPRO should be calibrated with a standard of that specific compound as
span gas. The 2020ComboPRO’s 15 memory slots can be used to store calibration
information for 15 different span gases.
NOTE: Even if the 2020ComboPRO has been calibrated with a specific compound, its
response is not specific and the presence of another ionizable impurity may render
the numerical result invalid.
It is often impractical to carry a range of different standards into the field.
Approximate results can be obtained by calibrating the 2020ComboPRO with the
recommended span gas and entering the appropriate response factor. The response
factor is based on the ratio of the response of the specific compound to the response
of the span gas. The response factor multiplies the 2020ComboPRO’s reading, then
displays and records it.
The list of response factors is available directly from INFICON’s web site at:
www.INFICON.com . This list should be used only for concentrations up to 500
ppm of the specific compound, as response factors can change with concentration.