Hoods

Fume Hoods

Chemical fume hoods are designed to provide protection to researchers from chemicals and radiological exposure. Any toxic or volatile (tendency of a chemical to vaporize) chemical must be used inside of a chemical fume hood to lower the chances of inhalation exposure.

The following work practices should be used to maximize the effectiveness of a chemical fume hood.

  1. Ensure that your chemical hood has a current inspection sticker (dated within the last 365 days)
  2. Verify that the chemical hood is drawing air. Check the flow monitor (if present) or use a "Kimwipe" to demonstrate flow into the hood.
  3. Use sashes to maximize protective shielding and ventilation.
    • Vertical sashes should be lifted sashes only as far as needed to do your work comfortably. Under no circumstances should the sash be lifted above the most current certification label.
    • For hoods equipped with horizontal sashes, slide the sashes to minimize the openings, keeping a panel between you and your work.
  4. Perform all work and keep all apparatus at least six inches into the hood. Performing work at least six inches inside the hood will help prevent disruptive air currents from developing at the hood face.
  5. Discontinue work if the flow alarm sounds during use. Inform the EHS office of the condition of the chemical fume hood.
  6. Perchloric acid should not be heated in a chemical hood unless it is specifically designated as a “Perchloric Acid Hood”.
  7. Chemicals, including hazardous waste, should not be stored nor allowed to evaporate inside the hood.
  8. Keep chemical hood sashes closed when the hood is not in use.
  9. Never put your head in the hood when chemical are in the hood or experiments are in progress.
  10. Route service connections under the airfoil. Electrical cords, tubing from compressed gas cylinders, etc should be under the airfoil to prevent disruption in air flow and allow the sash to be closed completely.
  11. Slots in the hood baffle should be free of obstructions and air allowed to flow freely inside chemical fume hood. Objects inside hood should be kept at least six inches from all edges of the chemical fume hood.

To report a problem with a fumehood, or to request certification, please go to our Report Chemical Fumehood Issues page.

Laminar Flow Hoods

Laminar flow hoods provide protection to samples by directing clean air toward the research or out of hood. This prevents any contaminated air from entering the laminar flow hood and contaminating samples. Laminar flow hoods must never be used when working with any infectious material or volatile/toxic chemicals.

Biological Safety Cabinets

Choosing the proper BSC for your laboratory can be a difficult process. Protection of personnel, protection of research samples, and cost of equipment and annual certification are just a few factors which should be taken into account. The following information is to be used as a guide to help you choose the appropriate equipment for your laboratory.

Types of BSCs

Class I BSCs provides personnel and environmental protection, but no product protection. Class I hoods can be either hard-ducted into a building exhaust system or allowed to circulate air back into the room. With both situations a HEPA filter is in place to provide protection to the environment. Users are protected by inward airflow.

Class II (types A1, A2, B1, and B2) BSCs provide personnel, environmental and product protection. Users are protected by inward airflow while a downward laminar flow of HEPA-filtered air provides product along the work surface of the cabinet. Air exhaust is passed through a certified exhaust HEPA filter which removes all contaminant. This air may be recirculated back into the laboratory (Type A) or exhausted out of the building.

Type A1—70% recirculated, 30% exhausted to a common plenum. In order to prevent the build-up of chemical vapors in the room, volatile chemicals must not be used.

Type A2—similar to type A1, but with a negative rather than positive pressure plenum. Type B3 has been replaced by a type A2-hard ducted to the building’s exhaust.

Type B1—designed for manipulations of minute quantities of hazardous chemicals with in vitro biological systems. This system does recirculate 30% of exhaust back into room so extremely volatile chemicals must not be used.

Type B2—system provides both biological and chemical protection by providing total external exhaust. Please note that some chemicals have the ability to degrade the HEPA filter causing a loss of containment.

Class III provides maximum protection to the environment and the worker and should be used when working with microbiological agents assigned to biosafety level 4.

Type Face velocity (lfpm) Airflow Pattern Radionuclides/Toxic Chemicals Biosafety Level(s) Product Protection
Class I* open front 75 In at front; rear and top through HEPA filter No 2, 3 No
Class II Type A 75 70% recirculated through HEPA; exhaust through HEPA No 2, 3 Yes
Type B1 100 30% recirculated through HEPA; exhaust via HEPA and hard ducted Yes (low levels/volatility) 2, 3 Yes
Type B2 100 No recirculation; total exhaust via HEPA and hard ducted Yes 2, 3 Yes
Type B3 100 Same as IIA, but plena under negative pressure to room and exhaust air is ducted Yes 2, 3 Yes
Class III NA Supply air inlets and exhaust through 2 HEPA filters Yes 3, 4 Yes

* Glove panels may be added and will increase face velocity to 150 lfpm; gloves may be added with an inlet air pressure release that will allow work with chemicals/radionuclides.

Biological Safety Cabinet Certification Form

The importance of proper certification cannot be emphasized enough, since persons who manipulate infectious microorganisms are at increased risk of acquiring an occupational illness when their BSCs are functioning improperly.

–Centers for Disease Control (CDC), Primary Containment for Biohazards

Biological Safety Cabinets must be inspected and certified by a trained technician annually. The EHS office contracts with Laboratory Certification Services, Inc. (LCS) to certify all BSCs on campus. The cost of certification is the laboratory's responsibility.

In order to schedule a certification please complete the Biological Safety Cabinet certification form.

If the laboratory is moving all BSCs must be decommissioned by a certified technician. Please review the laboratory equipment disposal and relocation information found on this website.


EHS | Service Building, first floor | 2220 Circle Dr | Cleveland, Ohio 44106 | 216.368.2906/2907 | does@case.edu
© 2011 Case Western Reserve University | Cleveland, Ohio 44106 | 216.368.2000 | legal notice