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“We made a strategic choice to start where customers could get the fastest and easiest return,” says Bob Karschnia, vice president of wireless for Emerson Process Management, referring to the company’s release a couple of years ago of wireless, self-organizing solutions at the instrumentation level. “This is because field sensor networks can be easily installed and deliver significant value without the need for investing in a plant-wide wireless infrastructure,” he says.
But a wireless field device isn’t just a different kind of transmitter; it is the product of a real breakthrough in technology and practice that is just now being seen for what it is, according to Peter Zornio, chief strategic officer for Emerson Process Management. “The adoption of wireless technology,” Zornio explains, “will be driven by the ability to extend and manage the flow of information around the plant truly without limits. This will drive work process and operational practice change as this new capability is utilized. That’s the definition of a technology discontinuity.”
Indeed, the implementation of process control strategies has long been constrained by a simple set of instrumentation costs: the transmitter itself, the time and labor required for engineering and implementing the installation, the running of wire back to a central control room and the distributed control system input/output (I/O) hardware itself. Over the years, the cost of transmitters has steadily decreased, as has the cost of I/O. It is the middle part the installation and the wiring of the device to the control system that continues to be the limiting factor.
ADD NEW MEASUREMENTS QUICKLY AND EASILY
Early adopters of wireless have been able to access many such measurements, and not all of them have been traditional analog process variables. For example, one early adopter uses wireless to advise in real time when pressure relief valves open and close. This minimizes the fines from regulatory agencies for accidental environmental discharges.
Another early adopter uses wireless to annunciate activation of emergency stop buttons, pressure and temperature switches and other alarms to the centrally located operator.
Other early adopters are monitoring water temperature and pressure at eye-wash stations and the actuation of safety showers remotely. With the addition of people-locating applications, operators are even able to tell who it was that actuated that safety shower or eye-wash station and route the appropriate assistance to the scene faster and with greater efficiency.
Early adopters also are monitoring additional process variables for process optimization. Temperatures, pressures and flow rates that were far too expensive to monitor at the operator console can now be brought there wirelessly.
WIRELESS SLASHES MEASUREMENT COSTS
There are an estimated 26 million wired HART devices installed and in service around the globe. But fewer than 25% of the installed HART devices have their digital data, including diagnostics, connected to the control system or to an asset management system. For years, it was difficult to connect the digital information stream to controllers and systems that were designed toonly see analog data streams.
But with WirelessHART adapters, like Emerson’s soon-to-be-released Smart Wireless THUM Adapter, all this will change. The THUM adapter is a device that sits on the 4-20 mA DC loop and is typically screwed into the unused conduit port on the transmitter. It draws its power from the loop, extracts the HART digital data from the field device and communicates via WirelessHART protocol to a gateway and, thence, into the host system.
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