Intrinsically safe Foundation fieldbus H1 networks

Application in the Pharmaceutical Industry
Boehringer Ingelheim Chemicals, Inc. is a bulk active pharmaceutical ingredient manufacturing facility in Petersburg, Va. The facility consists of three primary production buildings that have their interiors classified as hazardous areas (Figure 6). The classification for the buildings is generally Class 1, Divisions 1 and 2 and Groups C/D with a maximum temperature requirement of T3C. Our manufacturing processes are controlled primarily by an Emerson Process Management DeltaV control system.

We installed our first IS fieldbus system in the facility in 2001 as part of our Bay 34 Upgrade Project. We implemented an entity IS fieldbus, using barrier/repeaters with a maximum of four devices per segment. Figure 7 is photograph of a cabinet implementing an entity-based IS fieldbus system. This implementation meant our control system cabinets were large and required a large number of fieldbus segments.

We recently installed an automated solvent distribution system in our S1 production building to accurately deliver organic solvents and raw materials for cleaning and production to approximately 125 end-use points. As part of this project, we wanted to install an IS fieldbus infrastructure that would meet our project requirements, as well as provide capacity for future growth. Our S1 production building is four stories tall, divided into 10 vertical production bays and electrical rooms located in the north end of the building.

Our IS fieldbus design needed to meet the following requirements:

• Installation in a Class 1 Division 1 Group C/D area,
• Wiring to instruments in a Class 1 Division 1 Group B/C/D area,
• Optimize control performance and minimize segment-to-segment communications by allowing primary elements and final control elements of a control loop that are physically located on different floors in a bay to be connected to the same segment,
• Maximize the number of devices allowed per segment,
• Run trunk/segment across the full length of the S1 building to reach the north end electrical rooms, 
• Be an intrinsically safe system allowing our technicians to troubleshoot and work on the system without needing a hot work permit or having to shut down the process,
• Hot-swappable replaceable components,
• Provide room for future expansion and growth.

After evaluating available technologies, including our existing Bay 34 IS fieldbus, traditional IS fieldbus and FISCO systems, we contacted Chris Peters at Logical Innovations of Richmond, Va., our local MooreHawke representative to inquire about the Route-Master system. After talking with Chris, we learned that the Route-Master system would meet all our design requirements, as well as provide us future growth capabilities. We installed 15 segments with more than 100 instruments operating on the segments.

The Route-Master implementation, in conjunction with remote I/O, has allowed us to install four DeltaV controllers in the same amount of cabinet space (See Figure 5) that we originally used to install one controller. Since the installation, we have had no Route-Master component failures and have standardized the fieldbus installations in our facility around the Route-Master system.

	FIGURE 5: SAVING CABINET SPACE
	By using the Moore-Hawke IS system, BI Chemicals could install four DeltaV controllers in the same space that was originally used for one DeltaV.

Conclusions
Choosing and implementing fieldbus in a hazardous area can be a difficult task. To complicate the matter even further, non-incendive Foundation fieldbus (FNICO – Fieldbus Non-Incendive COncept) is gaining popularity, but that is a subject for another article. However, if you keep a few concepts in mind during your decision-making and design process, you can minimize the chance of getting bogged down in all of the complicated specifications and find your way to an optimal solution. I have summarized a few points to consider during your process in Table 7 below. I have also included a number of excellent documents on hazardous-area classification, intrinsic safety and Foundation fieldbus (many of which I referenced while writing this article) in the reference section of this article.

TABLE 7

1. Fieldbus Foundation.
2. AG-163, “Foundation Fieldbus Application Guide 31.25 kbit/s Intrinsically Safe Systems.”
3. AG-140, “Foundation Fieldbus Application Guide 31.25 kbit/s Wiring and Installation.”
4. FD-043, “Foundation Fieldbus Technical Overview.”
5. IEC 60079-27, “Electrical apparatus for explosive gas atmospheres: Fieldbus intrinsically safe concept (FISCO) and Fieldbus non-incendive concept (FNICO).”
6. NFPA 70- “National Electrical Code (NEC).”
7. NFPA 497 – “Recommended Practice for the Classification of Flammable Liquids, Gases or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Area.”
8. NFPA 499 – “Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.”
9. Factory Mutual, “FM Global Property Loss Prevention Data Sheets 5-1, Electrical Equipment in Hazardous (Classified) Locations.”
10. Factory Mutual, “Approval Standard for Intrinsically Safe Apparatus and Associated Apparatus for Use in Class I, I & III, Division 1, and Class I, Zone 0 & 1 Hazardous (Classified) Locations.”
11. ANSI/ISA-12.01.01-1999, “Definitions and Information Pertaining to Electrical Instruments in Hazardous (Classified) Locations.”
12. ANSI/ISA-RP12.06.01-2003, “Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety.”
13. ISA-TR12.2-1995, “Intrinsically Safe System Assessment Using the ENTITY Concept.”
14. Moore-Hawke.