Laboratory Fume Hood Exhaust Analysis

Sunil Lakshmipathy, Jensen Hughes
Steve McCawley, Jensen Hughes

Access the Recording

Laboratory units in higher education facilities are typically equipped with multiple fume hoods of varied specifications, intended to protect students and faculty by containing hazardous materials within the hood, and removing them through the exhaust system. In this case study, accidental release of flammable service gases in various types of commercial laboratory fume hoods were analyzed to evaluate the gas concentration at the fume hood exhaust using computational fluid dynamics (CFD) methods. Accidental flammable liquid spill scenarios, which can result in flammable vapor release into the fume hood exhaust system, were also evaluated. Further, a laboratory fume hood exhaust system serving multiple fume hoods was evaluated for the potential to satisfy NFPA 90A requirements to co-locate exhaust ducts in the same shaft as environmental air ducts.

This analysis demonstrated the need for reliable excess flow control valves or similar engineering controls to mitigate flammable gas exhaust for the evaluated scenarios. The presentation concludes with practical recommendations for laboratory users to evaluate where additional analysis may be required to adequately protect faculty and students.

Learning Objectives

  • Illustrate fume hood performance during accidental releases;
  • Explain mitigation measures in laboratories for accidental release of hazardous gas release or liquid spills;
  • Understand NFPA design guidelines for design of atmospheric air ventilation ducts; and
  • Demonstrate the value of a performance based design of co-located ventilation systems in laboratories used to exhaust hazardous gases and ventilation air.


Sunil works as a lead consulting engineer, specializing in performance-based design analysis of industrial hazard scenarios. He has worked on several research and industrial projects to analyze mitigation of dispersion and explosion hazard scenarios posed by process industries. He has more than 8 years of CFD software development experience for in-house and commercial applications. He received his Ph.D. in turbulent fluid flow analysis from Texas A&M University.

Steve is a licensed fire protection engineer with 21 years experience having delivered over 200 successful projects across multiple vertical markets. He is an expert in code consulting, the detailed design and commissioning of fire alarm and fire protection systems, hazardous materials analysis, and developing alternate methods of design and construction. Steve holds a master's in fire protection engineering from the University of Maryland.


Note: Abstracts and biographies are displayed as submitted by the author(s) with the exception of minor edits for style, grammar consistency, and length.