LABORATORY VENTILATION

1
LABORATORY VENTILATION

• FOR TULANE LABORATORY EMPLOYEES
• January, 2005

2
OBJECTIVES

• To learn about the different types of ventilation
  available in laboratories so that laboratory
  workers can become familiar with the types of
  equipment and the limitations associated with
  each type
• To learn tips and safe work practices on how to
  safely operate a fume hood and a biological
  safety cabinet
  
• To become familiar with the role of OEHS in the
  purchase and certification of fume hoods and
  biological safety cabinets

3
GOALS OF VENTILATION

• Ventilation may be designed to protect the worker
  from potentially hazardous inhalation hazards
  
• - toxic or volatile chemicals
• - particles or dusts
• - vapors or aerosols
• - infectious microorganisms
• - other inhalation hazards
• Ventilation may be designed to protect the
  product from contamination
  
• Ventilation may be designed with filters to clean
  the air being exhausted from the unit, thereby
  protecting the environment

4
CHEMICAL FUME HOODS

• Designed to protect the worker from toxic or
  hazardous chemicals
  
• 100 of air exhausted to outside
• No recirculation of air
• Baffles in back should adjust for work with
  chemicals of different volatilities and vapor
  densities
  

5
CHEMICAL FUME HOODS

• All chemical fume hoods at Tulane must have an
  alarm or airflow indicator device on them to show
  that they are operating properly
  
• Most chemical fume hoods should have a face
  velocity in the range of 80-100 fpm
  

6
CHEMICAL FUME HOODS

• Do not assume that your fume hood is operating
  properly. Check the alarm indicator. At the
  very least, use a piece of tissue paper and make
  sure it is drawn inward. IF NOT OPERATING
  PROPERLY, DISCONTINUE WORK WITH HAZARDOUS OR
  TOXIC CHEMICALS!

7
FUME HOOD SAFETY TIPS

• Keep the sash as low as possible
• Work at least 6 inches inside hood
• Keep work surface clear of unnecessary items
• Keep baffles clear of obstructions elevate
  large equipment off work surface
  

8
FUME HOOD SAFETY TIPS

• Avoid rapid movement into and in front of hood
• Pedestrian traffic in front of hood creates
  turbulence and can pull vapors out of hood and
  into operators breathing zone

9
FUME HOOD SAFETY TIPS

• Keep the amount of material in a hood to a
  minimum excessive clutter increases turbulence
  and reduces hood efficiency
  
• An airfoil helps to minimize undesirable
  turbulence when air entering the hood impacts the
  front edge of the floor of the hood be sure
  airfoil is installed and side panels are in place

10
FUME HOOD SAFETY TIPS

• Secure loose lightweight objects such as paper
  towels
  
• Run water in hood drains often to reduce odors
  that may develop in p-trap
  
• Ensure adequate illumination in hood
• Be aware that opening and closing lab doors can
  affect hood performance

11
FUME HOOD SAFETY TIPS

• Keep the sash clean and unobstructed
• Place cords and hoses under the airfoil so sash
  can be kept closed
  
• Practice good housekeeping
• Clean chemical residues and spills from interior
  hood surfaces

12
FUME HOOD SAFETY TIPS

• Do not place absorbent paper under heating
  appliances
  
• Do not place incompatible chemicals together
• Remember the emptier the hood, the better air
  currents can flow through it! Do not use hood as
  storage cabinet.
  

13
ROLE OF OEHS

• OEHS approves fume hood purchases after checking
  with Facilities Services or building engineers
  and the researcher to make sure the equipment
  will meet the researchers needs
• OEHS checks fume hood performance, usually on an
  annual basis, and reports problems to Facilities
  Services
  
• Contact OEHS or Facilities Services if you
  suspect there is a problem with the performance
  of your fume hood DO NOT USE TOXIC OR VOLATILE
  CHEMICALS if you suspect a potential problem

14
RADIATION FUME HOODS

• Designed for the workers protection.
• To be used for work with radioactive materials
• 100 of air exhausted to outside
• May contain HEPA filters (esp. for work with
  Iodine isotopes)
  
• Usually stainless steel construction
• Usually reinforced for heavy lead shielding

15
RADIATION FUME HOODS

• Most radiation fume hoods should have a face
  velocity of about 125 fpm
  
• Same safety tips as for chemical fume hoods apply

16
PERCHLORIC ACID FUME HOODS

• Work with perchloric acid can cause the formation
  of perchlorate salts which can accumulate in the
  hood and ductwork and become explosive
  

17
PERCHLORIC ACID FUME HOODS

• Designed for worker protection.
• To be used for work with perchloric acid
• 100 of air exhausted to outside
• Special washdown features to prevent perchlorate
  buildup in hood and ductwork
  
• Not to be used for flammables or other chemicals
  reactive with perchlorates
  

18
SLOT VENTILATION

• Designed to protect the worker from volatile
  materials
  
• 100 exhausted to outside
• Draws fumes toward the back of the work space and
  away from the workers breathing zone
  
• Often used in pathology or histology
  laboratories
  

19
CANOPY VENTILATION

• May be 100 exhausted to outside
• Not recommended for chemical use
• Draws fumes past workers breathing zone
• Best used for heat removal, such as in a kitchen

20
HEPA FILTERS

• HEPA stands for high efficiency particulate air
  filter
  
• A HEPA filter filters out particles not fumes
  and vapors
  
• HEPA filters are used in biological safety
  cabinets
  

21
CLASS I BIOLOGICAL SAFETY CABINET

• Designed for worker protection
• 100 exhausted through HEPA filter, then
  circulated directly back into the room
  
• Supply air is not filtered, so the product in the
  cabinet is subject to contamination by organisms
  present in the air supply
  
• May be equipped with arm-length rubber gloves

22
Laminar Flow Clean Bench

• Laminar flow clean benches are designed
  specifically to protect the product from
  contamination
  
• They are not designed to protect the operator

23
Laminar Flow Clean Bench

• Supply air passes through a HEPA filter over the
  work surface, then is exhausted to the room
  
• Exhaust air actually blows into the operators
  face
  
• Never handle toxic or infectious materials in a
  Laminar Flow Clean Bench

24
Biological Safety Cabinet (BSC)Selection
Approval

• Units are selected based upon the hazards posed
  by the infectious agent(s) utilized in the lab,
  the biosafety level, and the lab procedure(s)
  that will be conducted
• A PIs requisition to buy a unit(s) is forwarded
  from Purchasing to the OEHS for review and
  approval
  
• PI provides info to the OEHS on activities that
  will be conducted
  
• OEHS ensures PIs equipment and lab are adequate
  for the activities that will be performed
  
• Written approval is forwarded by the OEHS to
  Purchasing after being reviewed, and a
  determination concerning whether or not that unit
  will provide adequate protection for the
  activities to be performed is made.

25
CLASS IIA BIOLOGICAL SAFETY CABINET

• Protects the worker, the product, and the
  environment
  
• Most commonly used BSC, suitable for procedures
  with clinical specimens or cell cultures
  
• Some air is re-circulated within the cabinet
  through a HEPA filter, some air is exhausted back
  into the lab through another HEPA filter
  
• Not for use with toxic or flammable materials

26
CLASS IIB1 BIOLOGICAL SAFETY CABINET

• Provides protection for worker, product, and
  environment
  
• Provides containment of infectious aerosols
• Has high energy requirements and operating costs
• Some air is re-circulated within the cabinet
  through a HEPA filter, and some air is exhausted
  back into the lab through another HEPA filter
  
• Not for use with toxic or flammable materials

27
CLASS IIB2 BIOLOGICAL SAFETY CABINET

• Designed for protection of the worker, the
  product, and the environment
  
• Exhausts 100 of intake air through a HEPA filter
  back into the room
  
• Provides containment of infectious aerosols
• High energy requirements and operating costs
• Some air is drawn in past a HEPA filter over the
  work area, and some air is drawn in through the
  work opening and exhausted
  
• Not for use with toxic or flammable materials

28
CLASS IIB3 BIOLOGICAL SAFETY CABINET

• Designed to protect the worker, the product, and
  the environment
  
• Functionally the same as BSC IIA, except air is
  exhausted to the outside through a HEPA filter
  rather than back into the room
  
• Some air is drawn in through the work opening and
  is re-circulated within the cabinet after passing
  through a HEPA filter
  
• Can cause a buildup of hazardous concentrations
  if toxic or flammable materials are used

29
CLASS III BIOLOGICAL SAFETY CABINET

• Provides highest level of worker, product, and
  environmental protection
  
• Supply air is drawn through a HEPA filter and
  exhaust air is filtered through 2 HEPA filters
  installed in series before discharge to the
  outside
• Gas tight construction with rubber gloves

30
BSC CERTIFICATION

• Performed upon initial installation, after filter
  changes, after unit relocation, and when deemed
  necessary as problems arise
  
• Typically conducted annually
• Performed by individual(s) trained to perform
  certifications and troubleshoot units
  
• Conducted in accordance with the National
  Sanitation Foundation (NSF) International
  Standard No. 49 for Class II (Laminar Flow)
  Biohazard Cabinetry
• Includes all or some of the following tests HEPA
  Filter Leak, Inflow Downflow Velocity Profile,
  Airflow Smoke Patterns, Electrical, Noise,
  Lighting, and Vibration

31
BSC Use Safe Work Practices

• Operate the unit at least three to five minutes
  before beginning work to allow the cabinet to
  "purge"
  
• Wipe the unit work surface, (not including the
  supply filter diffuser), the interior surface of
  the window, and the surfaces of all materials and
  containers placed into the cabinet with an
  appropriate disinfecting solution
• Ensure proper placement of ones arms, absorbent
  towels, and materials inside the unit to prevent
  disruption to the airflow
  
• Ensure active work inside the unit from a clean
  to a contaminated area
  
• Decontaminate materials that will be removed from
  the BSC at the conclusion of work activities
  
• DO NOT PLACE ITEMS ON TOP OF THE UNIT

32
BSC Use Safe Work Practices

• Clean small spills immediately with an
  appropriate decontaminating solution and place
  cleaning items in a biohazard bag
  
• Consult OEHS for spills large enough to result in
  liquids flowing through the front or rear grilles
  that may require more extensive decontamination
  
• Gas decontamination, performed only by the OEHS
  or specially trained personnel, may be performed
  or required
  
• After a particular project involving the use of a
  highly infectious agent
  
• Prior to maintenance activities
• Prior to certification or performance tests
• Before HEPA filter replacement
• Before a unit is moved from one location to
  another
  
• After a major spill of a biohazardous material

33
BSC Use Safe Work Practices

• OEHS recommends that the use of natural gas or
  any other flammable material in a BSC be
  prohibited except for cabinets that are equipped
  with explosion-proof roof exhaust fans. Use of
  these materials in a BSC can present a potential
  fire or explosion hazard as air is re-circulated
  in the unit, can cause turbulence and disrupt
  airflow patterns, and the heat produced by a
  Bunsen burner can damage the HEPA filter.
• Electric burners and micro-incinerators may be
  workable alternatives to using gas. These
  devices, however, may still create heat and
  turbulent airflow in the cabinet. To minimize
  these effects, the electric burner or
  micro-incinerator should only be used at the rear
  of the workspace.

34
BSC Safe Work Practices for Maintenance Activities

• Call OEHS for guidance before commencement of
  work
  
• Ensure unit decontamination prior to maintenance
  activities requiring work inside of a
  contaminated plenum
  
• Do not allow maintenance personnel to
• perform work inside the unit without performing a
  surface wipe (i.e., change light)
  
• perform work with the UV Light ON
• cut holes in the unit
• change HEPA filters in the unit
• place items on top of the unit
• puncture the filters inside of the unit

35
DUCTLESS HOODS

• The use of ductless fume hoods is discouraged for
  most applications because
  
• There is no indicator to tell when filter needs
  to be changed
  
• Multiple chemicals can interfere with filtration
• Small spills can overwhelm the filtration system
• Etc.
• If used, the filter must be changed frequently in
  accordance with manufacturers recommendations

36
SUMMARY

• Chemical and radiation fume hoods exhaust 100 to
  the outside and can be used safely for work with
  toxic or volatile chemicals
  
• HEPA filters, usually found in biological safety
  cabinets, filter out particles, not fumes and
  vapors
  
• For best performance when using a fume hood or
  BSC, please follow suggested safety tips and safe
  work practices

37
SUMMARY

• BSCs are selected based upon the hazards imposed
  by the infectious agent(s) utilized in the lab,
  the biosafety level, and the lab procedure(s)
  that will be conducted
• Certification of BSCs and fume hoods is typically
  done on an annual basis and when new equipment is
  installed, relocated, or filters changed
  
• Call OEHS for guidance before maintenance
  activities commence on a BSC decontamination
  may be needed

38
Tulane UniversityOffice of Environmental Health
Safety (OEHS)www.som.tulane.edu/oehs Pam
Fatland, Chemical Safety Manager(504) 988-2800 /
pfatlan_at_tulane.eduKim Chapital, Occupational
Health Manager(504) 988-2870 /
kchapit_at_tulane.eduIf unable to proceed to quiz,
type the link below into your browserhttp//auror
a.tcs.tulane.edu/ehs/enterssn.cfm?testnum21
Proceed to Quiz