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

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

LABORATORY VENTILATION

FOR TULANE LABORATORY EMPLOYEES

January, 2005


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



• 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



• 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



• 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.


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


RADIATION FUME HOODS• Designed for the worker’s

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


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 accumulate in the hood and ductwork and become explosive


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


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 worker’s breathing zone

• Often used in pathology or histology laboratories


CANOPY VENTILATION

• May be 100% exhausted to outside

• 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, 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


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


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 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 posed 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 the OEHS on activities that will be

conducted– OEHS ensures PI’s 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.


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


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




• 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




• 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


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


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


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 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


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.


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


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 manufacturer’s recommendations


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


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

Tulane UniversityOffice of Environmental Health & Safety (OEHS)

www.som.tulane.edu/oehs Pam Fatland, Chemical Safety Manager

(504) 988-2800 / [email protected] Chapital, Occupational Health Manager

(504) 988-2870 / [email protected]

If unable to proceed to quiz, type the link below into your browserhttp://aurora.tcs.tulane.edu/ehs/enterssn.cfm?testnum=21

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http://www.som.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

fume hood purchases

hood performance slide

hood drains

hood efficiency

interior hood surfaces

certification of fume

place slide