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Types of Biosafety Cabinets

Biosafety cabinets are used as the primary means of containment for

working safely with infectious microorganisms. However, biosafety cabinets

are only one part of an overall biosafety program, which requires consistent

use of good microbiological practices.

Biosafety cabinets are designed to prevent biological exposure to personnel

and the environment and may also protect experimental material from being

contaminated when appropriate practices and procedures are followed.

 Three kinds of biosafety cabinets, designated as Class , and have been

developed to meet varying research and clinical needs.

Biosafety Cabinet Classications

Type of  

Cabinet

Agent

Classication (Biosafety

Level)

Average Inlet

Velocity

Protection

Class !ow " #oderate $isk %B&! ',

()

*+ ser only

Class - !ow " #oderate $isk %B&! ',

()

*+ %work opening

xed)

ser "

material

Class B

!ow " #oderate $isk %B&! ',

()

/00 %work opening

at 12)

ser "

material

Class High $isk %B&! (, 3) ser "

material

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Biological safety cabinets use high e4ciency particulate air %H56-) lters in

their exhaust and7or supply systems. These ltered cabinets are primarily

designed to protect against exposure to particulates, including biological

agents used in the cabinet. Protection against exposure from fumes

generate by raionuclies an toxic c!emicals is only provie by

Class II" Type B biosafety cabinets" #!ic! are ucte irectly to t!e

facility ex!aust$

T!e Class I Biosafety Cabinet

 The Class biosafety cabinet provides personnel and environmentalprotection, but no product protection. t has similar turbulent air 8ow as a

chemical fume hood, but has a H56- lter in the exhaust system to provide

containment and environmental protection. T!is oler class of biosafety

cabinet is rarely seen in %&'Cs biomeical an microbiological

laboratories$

Class I Biosafety Cabinets

A$ ront *pening 

B$ 'as! 

C$ +x!aust ,+PA 

-$ +x!aust plenum

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T!e Class II Biosafety Cabinet

T!e Class II biosafety cabinet provies protection to t!e user" t!eexperimental material an t!e environment$ T!e Class II biological

safety cabinet is t!e type most commonly use in %&'Cs

biomeical an microbiological laboratories$ -ir 8ow is drawn from the

room around the operator into the front grille of the cabinet, which provides

personnel protection. n addition, the downward laminar 8ow of H56-9ltered

air provides protection for experimental material inside the cabinet. Because

cabinet air has passed through the exhaust H56- lter, it is contaminant9

free, providing environmental protection, and may be recirculated back into

the laboratory %Class Type -) or ducted out of the building %Class Type B).

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Class II Biosafety Cabinet

A$ ront *pening B$ 'as! 

C$ +x!aust ,+PA lter 

-$ 'upply ,+PA lter 

+$ .ear plenum 

$ Blo#er

T!e Class III Biosafety Cabinet

 The Class biological safety cabinet is most suitable for work with

bioha:ardous agents requiring high contain %biosafety level ( or 3). The Class

cabinet is completely enclosed, H56- lter9ventilated cabinet tted with

glove ports and decontamination capabilities for entry and exit of material.

t o;ers the highest degree of personnel and environmental protection from

infectious aerosols.

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Class III Biosafety Cabinet

A$ <love ports with

=9ring for attaching

arm9length gloves

to cabinet

B. &ash

C. 5xhaust H56-

>. &upply H56-

5. >ouble9endedautoclave or pass9

through box

Clean Benc!es

 Though similar in appearance, clean benches are ?=T biological safety

cabinets. These cabinets intake room air which is passed through a pre9lter

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and a H56- lter to remove contaminants, dust and other particles. The

puried air then enters the work surface via a directed %non9turbulent) air

8ow. These cabinets provide product protection but do not provide user

protection. Clean benches must not be used when working with any form of 

bioha:ard or other type of ha:ardous material as they can increase the risk

of exposure.

Clean Benc!