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separate problem indicated by another variable. For example,
if the gas is being released by a faulty valve, an adjacent
pressure transmitter tied to the process automation system
may register falling pressure in the system, or it might trigger a
response from a safety instrumented function.
This gives plants the option of installing toxic gas
monitors, which can communicate via an existing
WirelessHART network (Figure 4).
There are now modular gas monitors designed from the
start for wireless operation, so they are fully internally
powered, eliminating the need for any field wiring. While the
main data is sent via the wireless network, the transmitter also
has internal contacts able to activate a local alarm, such as a
horn or beacon, if desired. The gas sensor is a self-contained
insert which can be plugged into the transmitter, simplifying
calibration tasks and even allowing for a different target gas,
such as carbon monoxide, to be implemented just by
substituting a different sensor. Even flammable gases will likely
be added to extend the capabilities of these devices.
These wireless gas monitors are designed for typical
refinery environments, are able to withstand temperature
extremes and exposure to the elements, and operate in most
hazardous areas (CSA Division 1, and ATEX and IECEx Zone 0).
Given their low purchase and deployment cost, these gas
monitors can be added to areas that were previously
considered too impractical to monitor using conventional
wired installations. As a result, worker safety can be improved
significantly at minimal cost. Monitoring system software is
also available as a customisable, pre-configured platform
(Figure 5) which is easy to set up and configure.
Integration by extending existing
networks
While location systems and toxic gas detection do not
integrate directly, they exist side-by-side on the same
WirelessHART network, and data from both can be used in
conjunction. For example, an alert from a wireless toxic gas
detector could prompt operators to check the location of
plant personnel who might be exposed.
In most cases, the existing WirelessHART network will
also carry data from field instruments to the main process
automation system. Once data reaches the gateway and
larger plant network, regardless of the originating device, it is
accessible and can be distributed to any part of the larger
network. If control room operators want to know whether
there is a toxic gas leak somewhere in the plant, the
necessary data is available for viewing.
Extending a network originally conceived to support
field instrumentation also supports digital transformation
and integration efforts because no part of a plant and no
internal system has to remain isolated. Even safety
instrumented systems can send data to other parts of the
plant while retaining their ability to function independently.
WirelessHART has proven its reliability over more than a
decade, allowing users to apply it in new ways they may have
not considered just a few years ago.
This kind of integration is not an end in itself but is
instead a means to implement new data collection and
analytics capabilities to improve plant performance and
worker safety, all at far lower costs as compared to
traditional solutions.
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