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Biological Safety Cabinets

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Class I BSC is a ventilated cabinet with an inward airflow and HEPA filters at its outlets. ... Class II, Type B cabinet originated when the National Cancer ... – PowerPoint PPT presentation

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Title: Biological Safety Cabinets


1
Biological Safety Cabinets
  • College of Biological Sciences

2
What are Biological Safety Cabinets (BSC)?
  • Containment and protection devices used in
    laboratories working with biological agents with
    a primary purpose of protecting the laboratory
    worker and the environment from viable organisms.

3
What is NOT a BSC!!!
  • Chemical Fume Hoods
  • Conventional lab fume hoods should NEVER be used
    to contain biological hazards.

Find a Biological Safety Cabinet!
4
This is also NOT a BSC!
Laboratory Laminar Flow Clean Benches
  • Clean Benches discharge HEPA filtered air across
    the work surface toward the user.
  • They provide protection only for product inside
    the bench.
  • They are commonly used for sterile assembly or
    dust free electronic production.
  • Clean benches should NEVER be used when handling
    cell culture materials, drug formulations, or
    manipulating potentially infectious materials.

Find a Biological Safety Cabinet!
5
Class I Biological Safety Cabinets
  • Class I BSC is a ventilated cabinet with an
    inward airflow and HEPA filters at its outlets.
  • It was previously referred to as the CDC Hood
    and served a valuable function in its time to
    protect personnel and the environment.
  • Because it offers no product protection, it has
    been essentially obsolete for the past several
    decades.

6
Class I Biological Safety Cabinet Schematic
7
Class II Biological Safety Cabinets
  • As biomedical researchers began to use sterile
    animal and cell tissue culture systems, BSCs
    utility needed to be expanded from simply
    protecting the operator to protecting the product
    as well.
  • Class II BSCs are Laminar Flow Biological Safety
    Cabinets that protect personnel, product, and
    environment.
  • They provide an inward airflow to protect
    personnel, a downward flow of HEPA filtered air
    to the work area to protect the product, and then
    exhaust HEPA filtered air to protect the
    environment from particulate and aerosol hazards.

8
Class II Type A BSC
  • Class II, Type A hoods are used to protect
    personnel, product and environment from
    biological aerosols and particulates.
  • These hoods offer personnel protection through
    negative pressure airflow into the cabinet.
  • To protect the product, the work area in the
    cabinet is continuously bathed with ultra-clean
    air provided by the supply HEPA filter.
  • Approximately 70 of the air of each cycle is
    recirculated through this supply HEPA filter.
  • The remaining air is discharged from the hood
    through the exhaust HEPA filter, protecting the
    environment.
  • Although not required, most Class ll hoods have
    the capability of being vented to the outside.

9
Class II Type A BSC Schematic
  • A- Front Opening
  • B- Sash
  • C- Exhaust HEPA Filter
  • D- Rear Plenum
  • E- Supply HEPA Filter
  • F- Blower

10
Class II Type B BSC
  • The Class II, Type B cabinet originated when the
    National Cancer Institute designed the Type 2
    (later-Type B) biological safety cabinet.
  • It was created for manipulations of minute
    quantities of hazardous chemicals such as
    carcinogens when used in research with in vitro
    biological systems.
  • Carcinogens used in cell culture or microbial
    systems require both biological and chemical
    containment.

11
Class II Type B 1 BSC Schematic
  • A- Front Opening
  • B- Sash
  • C- Exhaust HEPA Filter
  • D- Supply Plenum
  • E- Supply HEPA Filter
  • F- Blower
  • Connection to building exhaust
  • system required.

12
Class II Type B 2 BSC Schematic BSC is a
total-exhaust cabinet no air is recirculated
within it. This cabinet provides simultaneous
primary biological and chemical containment. The
supply blower draws in room air or outside air at
the top of the cabinet, passes it through a HEPA
filter and down into the work area of the
cabinet.
  • A. front opening
  • B. sash
  • C. exhaust HEPA filter
  • D. supply HEPA filter
  • E. negative pressure exhaust plenum
  • F. supply blower
  • G. filter screen
  • Note The carbon filter in the building exhaust
    is not shown.
  • The cabinet exhaust needs to be connected to the
    building exhaust system.

13
Class II Type B 3 BSC Schematic
This biological safety cabinet is a ducted Type A
cabinet having a minimum inward airflow of 100
lfpm. All positive pressure contaminated plenums
within the cabinet are surrounded by a negative
air pressure plenum. Thus, leakage in a
contaminated plenum will be into the cabinet and
not into the environment.
  • A. narrow front opening
  • B. sash
  • C. exhaust HEPA filter
  • D. supply HEPA filter
  • E. negative pressure exhaust plenum
  • F. supply blower
  • Note The carbon filter in the building exhaust
    is not shown.
  • The cabinet exhaust needs to be connected to the
    building exhaust system.

14
Class II BSC Modifications
Class II BSCs can be modified to accommodate
special tasks
  • The front sash can be modified by the
    manufacturer to accommodate a microscope
  • A rigid plate with arm holes can be added if
    needed.
  • The work surface can be designed to accept a
    carboy, a centrifuge, or other equipment that
    requires containment
  • Good cabinet design, microbiological aerosol
    tracer testing of the modification, and
    appropriate certification are required to ensure
    that the basic BSC systems operate properly after
    modification. Maximum containment potential is
    achieved only through strict adherence to proper
    practices and procedures.

15
Class III BSC or Glovebox
  • The Class III BSC was designed for work with
    Biosafety Level 4 microbiological agents and
    provides maximum protection to the environment
    and the worker.
  • It is a gas-tight enclosure with a non-opening
    view window.
  • Access for passage of materials into the cabinet
    is through a dunk tank that is accessible through
    the cabinet floor or double door pass-through box
    such as an autoclave that can be decontaminated
    between uses.
  • Reversing that process allows for safe removal of
    materials from the Class III BSC.
  • Both supply and exhaust air are HEPA filtered.
    Exhaust air must pass through two HEPA filters or
    a HEPA filter and an air incinerator before
    discharge to the outdoors.
  • Airflow is maintained by a dedicated independent
    exhaust system exterior to the cabinet which
    keeps the cabinet under negative pressure

16
Class III BSC or Glovebox
Long, heavy-duty rubber gloves are attached in a
gas-tight manner to ports in the cabinet and
allow for manipulation of the materials isolated
inside. Although these gloves restrict movement,
they prevent the user's direct contact with the
hazardous materials. The trade-off is clearly on
the side of maximizing personal safety. Depending
on the design of the cabinet, the supply HEPA
filter provides particulate-free, albeit somewhat
turbulent, airflow within the work environment.
17
Class III BSC or Gloveboxes
Class III cabinets are usually only installed in
maximum containment laboratories with controlled
access. They require special ventilation or
other support systems such as steam for
autoclaves.
18
Class III BSC Schematic
  • A- Glove Ports
  • B- Sash
  • C- Exhaust HEPA Filter
  • D- Supply HEPA Filter
  • E- Double Ended Autoclave or Pass Through Box

A chemical dunk tank may be installed beneath the
work surface of the BSC with access from above.
The cabinet exhaust needs to be connected to
the building exhaust system.
19
Safe Work Practices for BSC Use
  • Do not store equipment or supplies inside the
    cabinet.
  • Do not use the top of the cabinet for storage.
    The HEPA filter could be damaged and the airflow
    disrupted.
  • Make sure the cabinet is level. If the cabinet
    base is uneven, airflow can be affected.
  • Never disengage the alarm. It indicates improper
    airflow and reduced performance which may
    endanger the researcher or the experiment.
  • Never completely close the window sash with the
    motor running as this condition may cause motor
    burnout.
  • Cabinets should be placed away from doors,
    windows, vents or high traffic areas to reduce
    air turbulence.

20
Safe Work Practices for BSC Use
  • For BSC without fixed exhaust, the cabinet
    exhaust should have a twelve inch clearance from
    the ceiling for proper exhaust air flow. Also,
    allow a twelve inch clearance on both sides of
    the cabinet for maintenance purposes.
  • Never operate a cabinet while a warning light or
    alarm is on.
  • The operator should be seated with shoulders
    level with the bottom of the sash.
  • Perform all work using a limited number of slow
    movements, as quick movements disrupt the air
    barrier. Try to minimize entering and exiting
    your arms from the cabinet, but if you need to,
    do it directly, straight out and slowly.
  • Keep all materials at least four inches inside
    the sash opening.
  • To avoid excessive movements in and out of the
    cabinet, discard pipettes into a tray, container
    or biohazard bag within the cabinet.

21
Safe Work Practices for BSC Use
  • If a bunsen burner must be used, place it at the
    rear of the work area where the air turbulence
    from the flame will have the least possible
    effect on the air stream. Often the use of a
    flame is redundant in what should be a germ free
    work space.
  • All equipment which has come in contact with the
    biological agent should be decontaminated. The
    cabinet should be allowed to run for at least
    three minutes with no activity so that the
    airborne contaminants will be purged from the
    work area before removing equipment.
  • After all items have been removed, wipe the
    interior surfaces with disinfectant.

22
Biohazard Spill Control Inside a BSC
  • 1. Keep the BSC on.
  • 2. Put on protective gloves.
  • 3. Spray wipe walls, work surfaces, and
    equipment with decontamination solution.
  • 4. Flood tray top, drain pans, and catch
    basins with decontamination solution.
  • 5. Allow to stand for 20 minutes.
  • 6. Drain excess solution into cabinet base.
  • 7. Lift out tray and any removable exhaust
    grille work.

23
Biohazard Spill Control Inside a BSC
  • 8. Clean top and bottom surfaces with
    sponge/cloth soaked in decontamination
    solution.
  • 9. Replace tray and grille work.
  • 10. Place everything that is contaminated into
    autoclave pan.
  • 11. Drain decontamination solution from cabinet
    base into AUTOCLAVABLE containers.
  • 12. Autoclave.
  • 13. If gaseous decontamination is needed, call
    EHS at 292-1284.

24
Biological Safety Cabinet Certification
  • Your cabinet must be certified when first
    installed and then annually. It must be
    recertified anytime it is moved even within the
    same room. Before certification personnel
    arrive, remove all items from the cabinet and
    wipe it down with a disinfectant. This will
    expedite the certification. If you have any
    questions, or think there may be a problem with
    your cabinet, do not hesitate to contact EHS
    (292-1284). Any decontaminations, certifications,
    repairs or adjustments are to be made by
    qualified personnel.
  • One approved certification specialist is
  • Laboratory Certification Services
  • P.O. Box 12155, Columbus, Ohio 43212
  • (614) 486-0788.

25
And remember..
  • A laminar flow biological safety cabinet is a
    valuable supplement to good sterile technique,
    not a replacement for it.
  • If the cabinet is not well understood and
    operated correctly, it will not provide adequate
    protection for you or the environment.

College of Biological Sciences
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