INFICON 2020ComboPRO Portable Photoionization Detector - Manual (Page 59)

52 ISP-074-575-P1D 52
GAS Monitoring Mode for Benzene Measurement
In GAS mode, the benzene pre-filter tube (Part No. F1760161) should be used to
measure benzene. The GAS mode is a filter tube mode, so all benzene
measurements require the installation of the pre-filter tube holder (Part No.
A1790500) and one of the benzene pre-filter tubes. The benzene pre-filter tube,
which is mounted at the head of the tube holder, adsorbs all substances with the
exception of benzene in order to selectively measure benzene. The entire process is
menu driven. The selective benzene measurement value is displayed after 45
seconds.
Figure 16. 2020ComboPRO with pre-filter tube holder
Initial Display
When the 2020gasPRO powers up the user is asked whether or not the instrument
should be calibrated. If “yes” is selected, the instrument enters calibration mode and
the user should follow the display prompts. If “no” is selected, the instrument
display goes directly to Sample mode.
The following values are displayed: benzene concentration in ppm, STEL value, the
highest benzene measurement value recorded so far (SMAX), the amount of
measurements already carried out (SAMP) corresponds with the amount of benzene
pre-filter tubes already used, and the sampling interval period of 45 seconds (SECS).
Pressing the VIEW key shows the datalogger measurement values. Pressing the
MENU key takes you back to the selection menu. Pressing the SAMPLE key starts
the measurement: the pump is activated and measured air is drawn through the
benzene pre-filter tube for 45 seconds. The measurement status is indicated by the
flashing word SAMPLING. The display starts at 45 seconds under SECS and counts