38 • Chapter 3: Operation
GX-6000 Operator’s Manual
VOC Detection
When monitoring for VOCs using the PID sensor, keep the following in mind:
•
Regardless of what gas the PID sensor is calibrated to (factory calibration is to
isobutylene), the PID sensor will still detect and respond to a variety of volatile
organic compounds (VOCs).
•
The PID channel will indicate an upscale reading if one of a variety of combustible
gases is present. If %LEL concentrations of one of these combustible gases is present,
the PID channel may indicate an overscale reading.
•
If concentrations of methane greater than 10% LEL are present in the monitoring
environment, the PID channel’s reading will be suppressed.
•
The PID sensor will also respond to H
2
S and NH
3
, so if H
2
S or NH
3
is present, the
PID channel may indicate an upscale reading depending on the concentration present.
•
If your instrument has both a low range PID sensor and a high range PID sensor
installed and if you are monitoring for gases in the higher range, the low range PID
channel may be in over range alarm while monitoring, depending on the level of
VOCs present.
•
If you have 2 PID sensors installed, they might both be displayed as “VOC”. The
channel that appears first is based on the following sensor priority.
NOTE:
If you have changed the factory-set channel assignments using the
CONFIGURE CH
menu item in User Mode, the order of displayed sensors
may be different and you will need to remember how you set your instrument
up.
Oxygen Detection
Exposing the galvanic oxygen sensor to halogen gas or sulfides may shorten the sensor’s
life or cause malfunctions or inaccurate gas readings. Minimize the sensor’s exposure to
these gases as much as possible. If exposure occurs, allow the instrument to draw fresh air
and confirm that the readings return to fresh air values.
High Priority
Low Priority
10.6 eV low range PID
10.0 eV/benzene PID
11.7 eV PID
10.6 eV high range PID
