In prior posts on safety and regulatory standards and burner management functional safety, I highlighted some of the developments in standards for burner management systems (BMS). The DeltaV SIS process safety system recently received additional TÜV functional safety certifications:
- NFPA 85 – Boiler and Combustion Systems Hazards Code
- EN 50156-1 – Electrical equipment for furnaces and ancillary equipment. Requirements for application design and installation
- EN 298 – Automatic gas burner control systems for gas burners and gas burning appliances with or without fans
These certifications provide confirmation that DeltaV SIS is well suited for use in BMS applications, since all of these pertain to fire-heated equipment and their systems.
I put the question to Emerson’s process safety system team about why there are so many standards for burner management systems and which standard should be followed.
Mike Boudreaux shared with me that in addition to the standards listed above, there are even more standards, guidelines, and recommended practices that apply to burner management systems. BMS-related standards, guidelines, and recommended practices are published by National Fire Protection Association (NFPA), International Society of Automation (ISA), American Petroleum Institute (API), European Committee for Standardization (CEN), and FM Global (FM) organizations. Here are a few examples:
- IEC 61511 is a performance based safety standard, not directed at any one application, but for the process industry in general.
- ISA TR-84.00.05 is a technical report that provides guidance on the identification of safety instrumented functions in BMS applications.
- ANSI/API RP 556 – is a recommended practice for instrumentation and control systems for fired heaters and steam generators
- FM Approval Standard 7605 is a prescriptive standard that applies to PLC-based burner management systems.
The various BMS standards all serve the same purpose-they tell a process manufacturer how to avoid situations where dangerous failures could occur and they describe what to do when any of these situations are detected:
- Fuel supply should be off, but is not
- Flame should be on, but is not
- Process equipment is overheated
- BMS is prevented from working as it should
The standard process manufacturers choose to follow will be based on regulatory requirements, company policy, plant location, familiarity of standards, insurance requirements, and/or specific BMS application (e.g., boiler, furnace, type of fuel, etc.)
Chuck Miller noted that different BMS standards could also be used together, at the same time. For example, a prescriptive standard such as NFPA 85 can be used with a performance-based standard such as IEC 61511, and each standard has its own merits. In fact, one may bolster the value of the other to ensure best practices are being used for safety lifecycle management.
Chuck stresses that it’s also important to remember that product/system “certification” really means, “certified for use“, in a particular application. While this indicates that a system can meet the requirements of these guidance documents, the installer still has the challenge of configuring the necessary functionality. In addition, acceptance of the system and confirmation that the system does in fact meet the requirements typically lies with the local jurisdictional authority.
Andy Crosland summed up his views by pointing out that there are hazards associated with potential problems with fire-heated equipment, and the purpose of a BMS is to keep the equipment and personnel safe. Specific hazards for each burner, fuel, etc. should be analyzed and have appropriate protection measures applied.
IEC 61511 provides a framework for evaluating these hazards and implementing safety instrumented system (SIS) safeguards to protect against them. Prescriptive BMS standards provide requirements that state specifically what must be done. The prescriptive requirements can be used as the basis for the safety requirement specification in the IEC 61511 safety lifecycle management process.
