McMaster University

McMaster University


Requirement for Fume Hoods

  • handling of hazardous materials (solids, liquids or gas)
  • prevents exposure to fumes, vapours, dusts, and aerosols carried in air
  • provides a cleanable work surface
  • a temporary work surface - not a storage unit
  • breathing zone - the volume of air around your nose and mouth which has the potential to be inhaled under normal circumstances
  • face velocity - inward airflow from the sash in feet per minute (fpm)
  • safe working sash height is variable

Fume Hood Anatomy

  • sash
  • by-pass grill (CAV)
  • work surface
  • air foil
  • baffles
  • access ports
  • controller module
  • light switch
  • utility supplies
  • electrical supply
  • storage units

Alarms or Monitors

  • never turn off or deactivate alarms or monitors
  • if the alarm sounds or the monitor lights indicate low flow:
    • work should be stopped, close all containers, equipment turned off, and the sash lowered
    • lab personnel should leave the area if highly toxic or volatile chemicals are being used
    • if there is a likelihood that airborne contaminants will be released from the fume hood into the laboratory, please immediately contact your building services
    • report all problems to your supervisor immediately
  • verify control panel on your unit
  • read user manual
  • monitor air flow alarm
  • MUMC fumehoods using VentAlert system can change their battery according to these instructions.

Environmental Protection

  • fume hoods exhaust 100% of the air into the environment
  • no protection of the environment from hazardous fumes, vapors, aerosols and dusts
  • minimize these hazardous releases by keeping containers closed at all times
  • evaporation is prohibited as a method of chemical waste disposal


  • conditioned air (heated or cooled, humidified or dehumidified) is exhausted through fume hoods
  • fume hood exhaust systems run 24 hours a day, 7 days a week
    • are not put in low consumption states during off hours in the building like the air handling units
  • constant air volume systems are present in some buildings
    • do not allow for 'emergency purge' of fume hood even if you do have a controller panel with an emergency purge button
    • air consumption is not altered when the sash is closed
      • airflow increased through by-pass and air foil
  • variable air volume systems are present
    • allows for emergency purge of fume hood via controller panel if that feature is present
    • air consumption decreases when sash is closed

Specifications for Fume Hoods

  • manufacturer's specifications
  • user manual
  • CSA Z316.5-15, "Fume hoods and associated exhaust systems"
  • SEFA 1-2010, "Recommended Practices For Laboratory Fume Hoods"
  • ASHRAE 110-2016, “Method of Testing Performance of Laboratory Fume Hoods"
  • AEBC R-52 rev 1, "Design Guide for Basic and Intermediate Level Radioisotope Laboratories".

Preparing a Fume Hood for Work

  • review the SDS for the chemicals in use, review SOPs for work to be done
  • don PPE (lab coat, chemical resistant gloves, long pants, close toed shoes, eye protection)
  • verify an appropriate chemical spill kit is available
  • ensure you are aware of the closest emergency eyewash and shower
  • turn on the light, test the alarm and verify inflow velocity on the controller panel
  • verify certification is up to date by viewing sticker
  • open the sash and load your equipment, samples and reagents
  • work at least 6" inward from the air foil
  • do not block rear baffles
  • raise large objects by 3"
  • lower sash to working height or close vertical panels to ensure one panel is in front of you

Working in the Fume Hood

  • monitor the fume hood when performing ongoing or reactive experiments
  • keep pedestrian traffic to a minimum
  • avoid rapid or excessive movement in front of the fume hood
  • place:
    • experimental materials and equipment at least 6 inches back from the face
    • large objects two to three inches above the work surface
  • keep rear baffle openings clear
  • keep papers, paper towels, work surface diapers, vials, and other small objects from being drawn into the fume hood’s ventilation system

Maintain Air Flow

  • be aware of eddy currents inside the hood
  • never cause air turbulence close to the fume hood eg exhaust from other equipment
  • keep nearby doors and windows closed when working in a fume hood
  • keep people traffic away from a fume hood when in use
  • move slowly in the hood
  • don’t open the sash rapidly

Small Chemical Spill in Fume Hood

  • stop working immediately and assess for
    • personal contamination (proceed to emergency flushing equipment)
    • hazardous material release from fume hood
    • potential for fire or explosion
    • equipment damage
    • air flow status
  • notify laboratory occupants
  • retrieve chemical spill kit
  • apply absorbent materials
  • apply chemical neutralizer
  • collect absorbed liquids into a double poly lined bag, labelled
  • complete incident reporting per RMM1000

Heat Generation

  • equipment and experimental procedures can generate excessive heat
  • heat causes changes in air currents
  • heat causes air to expand
  • negative pressure of the fume hood may be overcome leading to relase into the user's breathing zone

Over Crowded Fume Hood

  • over-crowded fume hoods are a hazard
  • dispose or donate excess chemicals
  • move chemicals do another flammables / corrosives storage unit
  • prop up large equipment on blocks to allow air flow
  • most vapours flow down and accumulate at the work surface
  • recommend use of fume hood shelves

Other Precautions

  • do not use hot plates or heated stirrers in a fume hood  when flammables or combustibles are present
  • never use paper, paper towel, kimwipes or any light items which can get sucked up into the ducting
  • evaporation of hazardous chemicals is prohibited as a method of disposal
  • never modify a chemical fume hood
  • no other types of exhaust can be connected to the fume hood exhaust system without a proper engineering assessment by Facilities Services or your hospital host engineering department

Perchloric Acid Fume Hood

  • use of perchloric acid requires a specialized fume hood
  • contact if you have or use perchloric acid
  • stainless steel liner
  • coved corners
  • washdown system for ducting
  • removable baffles

Radioisotope Use

  • radioisotope use requires a fume hood designed for this purpose
  • approval from health physics
  • fume hood is assigned to you

After using Fume Hood

  • secure all containers of hazardous materials
  • let the fume hood run for 5 minutes
  • remove all hazardous materials and equipment
  • clean all work surfaces with water
  • fully close the fume hood sash

FHS Equipment Inventory Labels

  • all fume hoods in MUMC should have a FHSSO inventory label affixed. If there is no label, please notify
  • site visit to evaluate fume hood and affix label
  • send notification emails
    • when unit has been removed
    • when unit requires to be put out of service
    • when unit has been inspected or certified
    • when unit's contact person is updated
    • when there is an issue with the unit

Maintenance and Annual Certification

  • fume hoods are to be maintained by the users according to the manufacturer's instructions regardless of location
  • malfunctioning fume hoods are to be reported and put out of service
    • applying signage
    • notifying lab occupants
  • on campus buildings (MDCL, IAHS and CRL) are serviced by Facility Services
  • off-site locations are responsible for servicing their own fume hoods through the building's engineering department or external service provider
  • in all cases the fume hood is to be free of hazardous materials prior to servicing

Cleaning the Fume Hood

  • use cleaning solutions compatible with the chemicals in use
  • use cleaning solutions compatible with the surfaces of the fume hood
  • follow manufacturer's instructions for cleaning fume hood
  • clean the interior and exterior surfaces and sash periodically and after spills using deionized water; then wipe the areas down with a soap solution and rinse
  • use a long handled tool to reach back and sides of the fume hood
  • use a purpose tool for the sash i.e. the Glass Slider or the Glider

Emergency Exhaust

  • your fume hood may have a controller and an option for emergency exhaust
  • depending on your the HVAC system design, you may have constant air volume or variable air volume exhaust
  • constant air volume systems do not have the ability to increase exhaust even if your fume hood has a control panel with an emergency exhaust button
  • contact your building maintenance service to verify if your emergency exhaust switch on your fume hood is active

Downdraft Tables

  • downdraft or necropsy tables are specially designed work areas with ventilation slots on the sides of the work area
  • useful for work with human anatomical specimens and animal perfusions and other uses of chemicals with vapor densities heavier than air
  • stainless steel table on wheels with slotted sides to capture toxic vapours and fumes from anatomical specimens
  • also contains a sloped surface designed to collect fluids in a collection container beneath the table
  • port for attaching exhaust source, detachable for movement of cadavers
  • detailed equipment-specific training through the anatomy program

Elephant Trunks or Snorkels

  • local exhaust ventilation
  • not a substitute for a fume hood
  • potential for contaminants to enter the user's breathing zone is high
  • requirement for LEV to be registered with FHSSO and reviewed by JHSC
  • SOPs to be generated by users and reviewed by JHSC
  • tubing attached to the ventilation system to allow for highly localized exhaust
  • exhaust area is very limited
  • must be very close to hazard for effectiveness
  • capture of contaminant is only effective within a distance of one duct diameter
  • capture velocity required is dependent on the application i.e. passive capture or active capture
  • flanged openings capture more contaminant than non-flanged openings

Fume Canopy

  • constructed in a similar fashion to the overhead canopy hoods seen in kitchens
  • in order for the canopy hood to be able to capture contaminants, the hood requires a relatively large volume of air movement, making them somewhat costly to operate
  • the canopy hood works best when the thermal or buoyant forces exist to move the contaminant up to the hood capture zone
  • they are designed such that the contaminated air passes through the user's breathing zone
  • the airflow is easily disrupted by cross currents of air
  • canopy hoods should only be used for exhaust of non-hazardous substances i.e. steam, odors from urine or fecal samples
  • capture velocity required for effectiveness highly dependent on contaminant and process employed
  • ACGIH Ventilation Manual

Other Ventilation Equipment

  • slot ventilation table
  • walk-in fume hoods
  • glove boxes

Follow Up Expectations

  • this awareness information to explain principles of equipment and basic function
  • supervisor or competent person to demonstrate functioning of a fume hood, any special features and emergency procedures
  • your supervisor shall ensure that you are to be chaperoned until the supervisor or competent person deems that you are proficient in fume hood use
  • your supervisor shall provide you with equipment-specific, experiment-specific and lab-specific SOPs related to the fume hood
  • if you are unsure about anything, ask your supervisor or contact the FHS Safety Office


Updated 2021-11-09


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