The National Fire Protection Association (NFPA) 85, Boiler and Combustion Systems Hazards Code has been a guiding industry standard for Burner Management System (BMS) design for many years. Contained within this standard is specific guidance on what hardware is needed in a BMS for certain functions. However, there is not much specific guidance on how to implement this hardware to deliver a desired level of risk reduction for each function.

The recently published ANSI/ISA-84.00.01-2004 standard (S84) covers Safety Instrumented Systems for the Process Industry Sector and provides a roadmap on how to implement hardware and software elements of a Safety Instrumented System. Combining the hardware guidelines of NFPA 85 with the implementation principles of the S84 standard and specifying a required level of risk reduction gives guidance for a complete design for a boiler's BMS.

This paper demonstrates:

1. How the Layer of Protection Analysis (LOPA) approach was used to establish the Safety Integrity Level (SIL) requirements for a single-burner, natural gas-fired generic NFPA85-compliant boiler. 2. How these results were used to verify compliance with Rohm and Haas Company's risk tolerance criteria. 3. How these results were used to assist in the development of a Corporate Combustion System Safety Standard.