tulane university - office of environmental health & safety (oehs) laboratory ventilation for...

Tulane University - Office of Environmental Health & Safety (OEHS)

LABORATORYVENTILATION

FOR TULANE UNIVERSITY LABORATORY & DESIGNATED

FACILITIES EMPLOYEES

May 2012


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


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


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


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


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!


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



• 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 operator’s breathing zone


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


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



• 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


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.


RADIATION FUME HOODS• Designed for worker protection 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


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


PERCHLORIC ACID FUME HOODS

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


PERCHLORIC ACID FUME HOODS

• Designed for worker protection 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


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 researcher’s 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


SLOT VENTILATION• Designed for worker

protection from volatile materials

• 100% Exhausted to outside• Draws fumes towards back of

work space away from worker’s breathing zone

• Often used in pathology or histology laboratories


CANOPY VENTILATION

• May be 100% exhausted to outside, but not recommended for chemical use

• Draws fumes past worker’s breathing zone

• Best used for heat removal such as in a kitchen


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


CLASS I BIOLOGICAL SAFETY CABINET

• Designed for worker protection• 100% Exhausted through HEPA filter

directly back into the room• Supply air not filtered, so product in

cabinet is subject to contamination by organisms present in the air supply

• May be equipped with arm-length rubber gloves


Laminar Flow Clean Bench

• A laminar flow clean bench is designed specifically to protect the product from contamination

• Not designed to protect the operator


Laminar Flow Clean Bench

• Supply air passes through HEPA filter over work surface, then is exhausted to the room

• Exhaust air actually blows into operator’s face

• Never handle toxic or infectious materials in a Laminar Flow Clean Bench


Biological Safety Cabinet (BSC)Selection & Approval

• Units 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

• A PI’s requisition to buy a unit(s) is forwarded from Purchasing to the OEHS for review and approval– PI provides info to OEHS on activities that will be

conducted– OEHS ensures PI’s equipment needs and lab are adequate

for the activities that will be performed• Written approval is forwarded by OEHS to Purchasing upon

review and determination that unit will provide protection needed for the activities that will be conducted.


CLASS II TYPE A BIOLOGICAL SAFETY CABINETS

• Protects the worker, the product, and the environment

• Most commonly used BSC, suitable for procedures with clinical specimens or cell cultures

• Some air is recirculated within cabinet through a HEPA filter, some air is exhausted back into lab through another HEPA filter

• Two (2) Subtypes– A1 – “freestanding” unit– A2 – unit with a thimble connection

• Do not use toxic or flammable materials


CLASS II TYPE B BIOLOGICAL SAFETY CABINETS

• Provides protection for worker, product, and environment• Provides containment of infectious aerosols• Units are hard-ducted• Two (2) subtypes

– B1 – Recirculates some air within the cabinet– B2 – Does not recirculate air in the cabinet

• Exhaust requirements– Sufficient building air needed to operate– Install an alarm– Interlock units fan with the building exhaust system– Fan required on the roof

• Do not use toxic or flammable materials


CLASS III BIOLOGICAL SAFETY CABINET

• Gas tight construction with rubber gloves

• 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

• Provides highest level of worker, product, and environmental protection


BSC CERTIFICATION

• Performed on new unit before usage, after filter changes, after a unit is moved from one location to another, and when deemed necessary if a problem arises

• Typically conducted annually by an outside contractor through OEHS

• Performed by individual(s) trained to perform certifications and troubleshoot unit

• 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


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 one’s 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


BSC Use & Safe Work Practices• Clean small spills immediately with an appropriate

decontaminating solution and place items used to clean 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 OEHS or specially trained personnel, may be performed or required:– After a particular project involving 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


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 recirculated 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 in the rear of the workspace.


BSC Safe Work Practices for Maintenance Activities

• Call OEHS for guidance before commencement of work

• Ensure unit is decontaminated prior to maintenance activities requiring work inside of a contaminated plenum

• Do not allow maintenance personnel to:

– perform work (i.e., change light) inside the unit without performing a surface wipe

– perform work with the UV Light “ON”

– cut holes in the unit

– change HEPA filters in the unit

– sit items on top of the unit

– puncture the filters inside of the unit


DUCTLESS HOODS

• The use of ductless fume hoods is discouraged for most applications (Problems: No indicator to tell when filter needs to be changed, multiple chemicals can interfere with filtration, small spills can overwhelm filtration system, etc.)

• If used, filter must be changed frequently in accordance with manufacturer’s recommendations


SUMMARY

• Chemical and radiation fume hoods exhaust 100% to the outside and can safely be used 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


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 or filters changed

• Call OEHS for guidance before maintenance activities commence on a BSC – decontamination may be needed

Tulane UniversityOffice of Environmental Health & Safety (OEHS)

Pam Fatland (504) 988-2800Kim Chapital (504) 988-2870

http://tulane.edu/[email protected] or [email protected]

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http://tulane.edu/oehs

mailto:[email protected]

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tulane university - office of environmental health & safety (oehs) laboratory ventilation for...

Documents

tulane university office

hood efficiency

biological safety cabinets

certification of fume

role of oehs

work surface slide

environment slide

fpm slide