Chemical Engineering April 2019 - 46

Environmental Manager
Key Considerations for the Use
of Portable Gas Detectors
Recent advances in gas-monitoring technologies can greatly increase worker
connectivity and safety
Tony Downes and Thomas Negre
Honeywell Safety and
Productivity Solutions
W
ith increased automation,
expanding
areas of operation and
smaller teams of field
workers, monitoring personnel and
ensuring lone worker safety are serious
challenges for the chemical process
industries (CPI). When operators
and technicians are in danger, it
is crucial to know their location and
react in a fast and effective manner.
Recent developments in portable
gas detection leverage new technology
for improved protection of the
industrial workforce by connecting
wearable detectors with the distributed
control system (DCS) through
the cloud to provide expanded
visibility of plant floor operations
- helping to keep workers safe
and promoting better emergency
response (Figure 1).
Today's safety challenges
Process operations, such as those
found in the CPI, often involve the
use or manufacture of hazardous,
flammable or toxic gases, which
have the potential to escape and
threaten those working within plants
or possibly even those living nearby.
Incidents may escalate, resulting in
environmental damage, explosions
or loss of life.
Plant workers have been carrying
different types of portable gas
detectors for years - one of them
being their nose (Figure 2). So, it
is already understood that detecting
and avoiding noxious gases
is a valuable capability. But some
hazardous gases cause " olfactory
fatigue, " meaning that the exposed
person's sense of smell diminishes
over time.
46
Hydrogen sulfide
(H2S) is a
particularly hazardous
gas commonly
found
at
industrial
sites.
It has a distinctive
" rotten egg "
smell at low concentrations.
H2S
is relatively easy
to detect at 0.01
parts per million
(ppm), but above
100 ppm, it is no
longer discernible.
Olfactory fatigue
can happen
so fast that people
can easily be
overcome without
realizing they are
being exposed.
Low-oxygen
areas are another
significant threat
to plant personFIGURE
1. Gas detection has always been essential in CPI operations, but as
manufacturing complexes have expanded and operations teams have shrunk,
remote monitoring technologies are increasingly required to ensure safety
nel. Human beings normally breathe
air that is 20.9 vol. % oxygen under
normal atmospheric pressure conditions.
When the concentration
of oxygen decreases even slightly,
they immediately begin to feel
the effects.
Tragically, there have been situations
where a " lone worker " in an industrial
facility succumbed to either
a lack of oxygen or the presence of
a toxic gas. By the time anyone became
aware that the worker was in
danger, it was too late.
Progress in gas monitoring
Portable gas monitoring was introduced
over 50 years ago and has
been evolving ever since. It is regularly
used to detect toxic or combustible
gas - or preferably to confirm
the absence of such gases. Monitoring
systems provide early warning
of an abnormal situation before it
becomes a significant threat.
Current technology has allowed
the capabilities of portable gasmonitoring
devices to be continuously
extended. In the past, two
detectors were needed to confirm
there were no flammables, and the
oxygen concentration was normal,
before allowing entry into a confined
plant space. Subsequent developments
have allowed a single monitor
to be set up with a pump and sampler
to provide continuous indication
with an alarm.
However, workers in many jobs
face risks that require detectors that
can handle multiple gases at once.
These more complex multi-gas
devices are also increasingly mandated
by new regulations. A single
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