Print this page Fire Dynamics Series: Predicting Hot Gas Layer Temperature and Smoke Layer Height in a Room Fire with Natural and Forced Ventilation
Lawrence J. Marchetti, P.E., CFPS
Course Outline
The following course reviews selected fire protection fundamentals and describes the methodology for calculating the hot gas layer temperature and smoke layer height in a compartment fire. The following Fire Dynamics Course Material is from the U.S. Nuclear Regulatory Commission (NRC) and is referred to as “Fire Dynamics Tools” (FDTs). This course material was implemented by the NRC to assist their regional fire protection inspectors in performing fire hazard analysis (FHA). Although the material was prepared for NRC fire protection inspectors, the material presented is fundamental in nature and not specific to a nuclear power plant environment.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of course materials.
DISCLAIMER:
The following course material is informational in nature and is designed to introduce the principals of fire dynamics to non-fire protection engineers. The NRC developed materials rely on simplified empirical equations that may not be appropriate in all design situations. Each of the Fire Dynamics methods have limitations as stipulated within the text. These equations at best provide rough estimates and the examples in the course were specifically tailored for Nuclear Power Plant (NPP) environments. Therefore the arbitrary use of this information in “real-world” design situations is strongly discouraged without the expertise of a competent licensed fire protection engineer. PDH Online nor the Course Provider assume any liability for use of this information or for inaccuracies contained in the course material contained herein.
Learning
Objective
At the conclusion of the course, the student should be able to perform the following:
- Explain the different stages of a compartment fire;
- Understand the phenomena of “flashover” in a compartment fire;
- Identify the types of forced and natural ventilation systems;
- Explain how the various types of forced air ventilation systems work;
- Understand the importance of determining the hot gas layer temperature and how it relates to flashover;
- Describe how to calculate the hot gas layer temperature and smoke layer height for a fire;
- Understand the various correlations used to estimate the hot gas layer temperature and smoke height as well as the assumptions and limitations that govern their use;
- Describe the steps in performing a fire hazard analysis and developing a fire scenario; and
- Describe how to calculate the hot gas layer temperature and smoke layer height for a fire in a compartment with both natural and forced ventilation systems.
Intended Audience
The following course is primarily targeted to Architects and Engineers, and others with little experience in Fire Protection Engineering concepts. The material is presented in a format that extensive use of mathematics and in-depth scientific theory is avoided.
Benefit for Attendee
The following course will present basic fire protection concepts to permit the attendee to understand the importance of smoke and gas layer height and temperature which affect the heat flux to the compartment and subsequent flashover.
Course Introduction
Fire Dynamics is defined as the scientific description of fire phenomena (e.g., ignition, flame spread, burning, smoke spread) in quantitative terms. It encompasses chemistry, physics, mathematics, fluid mechanics as well as heat and mass transfer.
The following Fire Dynamics Course Material is from the U.S. Nuclear Regulatory Commission (NRC) and is referred to as “Fire Dynamics Tools” (FDTs). This course material was implemented by the NRC to assist their regional fire protection inspectors in performing fire hazard analysis (FHA). These methods have been implemented in spreadsheets and taught at the NRC’s quarterly regional inspector workshops. FDT were developed using state-of-the-art fire dynamics equations and correlations that were preprogrammed and locked into Microsoft Excel® spreadsheets are available for download from the NRC website at http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/final-report/index.html#pubinfo. These FDTs will enable engineers and architects to perform quick, easy, first-order calculations for the potential fire scenarios using today’s state-of-the-art principles of fire dynamics. Each FDTs spreadsheet also contains a list of the physical and thermal properties of the materials commonly encountered in construction. The NRC course materials were derived from the principles developed primarily in the Society of Fire Protection Engineers (SFPE) Handbook of Fire Protection Engineering, National Fire Protection Association (NFPA) Fire Protection Handbook, and other fire science literature. The subject matter of this course covers many aspects of fire dynamics and contains descriptions of the most important fire processes. A significant number of examples, reference tables, illustrations, and conceptual drawings are presented in this course series to aid in comprehension of the principals presented.
Note: Text Errata is included at the end of the Course Material and should supersede material in the text.
Course Content
The course material is from the U.S. Nuclear Regulatory Commission (NRC) and is referred to as “Fire Dynamics Tools” (FDTs). This course material was implemented by the NRC to assist their regional fire protection inspectors in performing fire hazard analysis (FHA). You are required to study Chapter 4 and Chapter 5 for this course:
Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.
Course Summary
Fire Dynamics is defined as the scientific description of fire phenomena (e.g., ignition, flame spread, burning, smoke spread) in quantitative terms. It encompasses chemistry, physics, mathematics, fluid mechanics as well as heat and mass transfer. This introductory course presents basic compartment fire dynamic fundamentals necessary to understand future courses which will provide a more detailed look at fire phenomena as well as enhancing knowledge in fire protection.
Related Links
For additional technical information related to this subject, please visit the following websites:
U.S. Nuclear Regulatory Commission (NRC) – http://www.nrc.gov/
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
