Contact us
800-407-4294
It appears that your cart is currently empty
Exhaust Plume Height Calculator
Plume Height Calculator
Estimate the effective plume height for your lab exhaust fan.
Fan Characteristics
CFM
inches
feet
Environmental Conditions
MPH
°F
°F
Disclaimer: These results are an estimate and should not replace a professional engineering analysis.
Several standards and organizations provide guidance on lab exhaust fan design, including minimum plume height and exit velocity. The goal of these standards is to prevent the re-entrainment of hazardous fumes into the building's air intakes or nearby buildings.
- ANSI/ASSP Z9.5: Laboratory Ventilation: This is a key standard in the United States that establishes minimum requirements and best practices for laboratory ventilation systems. It addresses design requirements, performance testing, and the management of ventilation plans. It recommends a minimum exit velocity to prevent "stack-tip downwash," where the exhaust plume is pulled downward by negative pressures around the fan stack. A common recommendation from this standard and others is a minimum exit velocity of 3,000 fpm (feet per minute).
- ASHRAE Standards: The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) provides extensive guidelines for HVAC design, including lab ventilation. The ASHRAE Laboratory Design Guide is a critical resource and contains equations and methods for calculating plume rise. They often recommend a minimum exit velocity between 2,000 to 3,000 fpm.
- NFPA 45: Standard on Fire Protection for Laboratories Using Chemicals: While primarily focused on fire safety, this standard also contains requirements related to the design and operation of exhaust systems to prevent the accumulation of flammable vapors.