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Chemical process analysis visionaries, spurred by the successful use of modular sampling systems and manifolds (Figure 1) for ultra-pure gases in the semiconductor industry, have launched a major effort to define and adopt a new vision of process analyzer sampling systems, sensors, and connectivity, with diagnostics and the smarts to optimize their performance.
Formally created at ISA Expo 2000, the New Sampling/Sensor Initiative (NeSSI) is a vendor-neutral and non-affiliated effort that operates out of the Center for Process Analytical Chemistry (CPAC) at the University of Washington in Seattle. Peter van Vuuren of ExxonMobil Chemical, Baytown, Texas, observes that it has grown into "an ad hoc industry initiative to drive permanent change in how we do process analytical [chemistry]."
As of May 2002, the NeSSI effort has more than 300 e-mail subscribers representing over 30 end users in the oil and petrochemical industry, manufacturing companies, equipment vendors, academia, and national laboratories. Their goal: reduce the design, assembly, installation, and operating and maintenance costs of sample handling systems. Their plan: facilitate the development and evaluation, over three generations, of:
1. Modular sampling system designs using standardized surface-mount hardware that is compliant with ANSI/ISA-76.00.02-2002, Modular Component Interfaces for Surface-Mount Fluid Distribution Components-Part 1: Elastomeric Seals (SP76).
2. Software and plug-and-play hardware for smart sampling systems that optimize their performance by altering pressure, flow, temperature, and in the future, other operating parameters. This hardware also would be certified for use in hazardous areas (intrinsically safe) and enabled for non-proprietary communications solutions.
3. Open standards for wireless communication and hardware for miniaturized analytical instrumentation.
History and Lore
Exactly when the concept of a modular sampling system first originated is hard to pin down. Work that started as early as 1994 resulted in a patent, Modular Sample Conditioning System, U.S. Patent 5,841,036, filed in August 1996 and issued to Don Mayeaux, president, A+ Corp., Prairieville, La., in November 1998. That may represent the beginnings of efforts to modularize sample conditioning systems.
However, it appears that the industry-wide initiative on the need for new approaches to sampling started within the Oil and Petrochemical Industry Focus Group at CPAC. "However, there was a consensus that the problem was not unique to petrochemical and that sampling was a concern in the food and consumer products, pharmaceutical, biotech, and the chemical process industries, and that there was a need for projects in sampling and sampling systems," recalls Mel Koch, director of CPAC, who formerly had global responsibility for analytical sciences at Dow Chemical.
Figure 1: Heart of the Beast
The essence of NeSSI is using modular components mounted on a standard substrate to build sample conditioning and analyzer systems. (Source: Swagelok)
"The CPAC group wanted to develop a concept for a flexible and smart sampling system that would be low-maintenance, require lower volumes (smaller samples), and be amenable to microanalytical devices," says Jim Tatera, senior process analysis consultant and president of Tatera and Associates, Madison, Ind. "The modular approach really took off when people piggybacked the concept with the SP76 standard for a modular sampling interface, the so-called surface mount technology, allowing it to move forward with some flexibility and interchangeability."
The SP76 standard is based on the semiconductor industrys concepts for surface mount technology. However, Mayeaux argues that the development of a standard for modular sampling and sample conditioning systems should have "wiped the slate clean; to design something that would be best for sample conditioning and analytical applications rather than adapt technology developed for control purposes."
"The way we approached it was to consider what we hoped to accomplish and what we wanted in the substrate and component interface design," relates Bac Vu, analytical specialist, Dow Chemical, Freeport, Texas. "There were features in the semiconductor design that were useful and that we felt we could implement in the chemical industry. We did not duplicate their design, but used it as a starting point to derive something to suit our needs. It has also given vendors an impetus to drive further development of sample conditioning technology, which we feel is an area that has been stagnant in terms of technological advancement and development."
Benefits Run Deep
Despite differences in the mechanical and engineering details of components and substrates, the interface designs are compliant with SP76 and the modular sample system concept embodied in NeSSI will help reduce the high lifecycle costs associated with conventional sampling systems. These costs include design and engineering, assembly, training, installation, startup, and maintenance.
"The biggest advantage of the NeSSI approach is it provides a standardized design and a smaller footprint for the sample system. It also provides a standardized approach that greatly simplifies the design effort because it provides for a [standardized] substrate and components that are carefully designed and defined for the particular application," says Rajko Puzic of Imperial Oil's Products and Chemicals Div., Sarnia, Ontario. This standardization and modularity (Figure 2) also greatly simplifies assembly, "So there is no variability. If I put 10 systems in service and theyre all the same, I most likely wont have to go through special cleaning or additional effort to make them work the first time out."
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