Basic Documentation
Table Of Contents
- Introduction
- Applicable Definitions (Alphabetical Listing)
- Laboratory Safety
- Hazard Assessment
- Chemical Hygiene Plan
- Chemical Hygiene Responsibilities
- Fume Hoods
- When Required & Safe Usage
- Gloveboxes:
- Face Velocity
- Face Velocity Setback
- Size & ADA Compliance
- CAV (Constant Air Volume) Bypass
- CAV (Constant Air Volume) Conventional
- VAV (Variable Air Volume)
- VAV Diversity
- Automatic Sash Closure
- Safe Operation of Sashes
- Accessories, Services and Explosion Protection
- Ductless
- Auxiliary Air
- (Special Purpose) Perchloric Acid
- Room Air Cross Currents
- Minimum Exhaust
- Monitoring
- Selection Criteria and Performance Specifications
- Laboratory Design & Fume Hood Implementation
- Maintenance
- Periodic Testing
- Test Procedures
- Signage and Recordkeeping
- Shutdown Procedures
- Evaluating CAV (Constant Air Volume) Systems
- Evaluating VAV (Variable Air Volume) Systems
- Biological Laboratories
- Biosafety Level 1
- Biosafety Level 2
- Biosafety Level 3
- Biosafety Level 4
- Ventilation for Biosafety Level 1
- Ventilation for Biosafety Level 2
- Ventilation for Biosafety Level 3
- Ventilation for Biosafety Level 4, Cabinet Laboratory
- Ventilation for Biosafety Level 4, Suit Laboratory
- Containment Levels - Canada
- Containment Levels and Ventilation Requirements: Canada
- Biological Safety Cabinets and Classifications
- Biosafety Cabinet Applications
- Biosafety Cabinets – Installation and Safe Usage Recommendations
- Biosafety Cabinets – Certification and Safe Usage - Canada
- Biological Safety Cabinet Design, Construction and Performance Requirements
- Biosafety Cabinet Testing
- Ventilation Systems
- Local Ventilation -When Required
- Ventilation Rates for Animal Rooms
- Ventilation Rates for Animal Rooms
- Ventilation Rates for Biological Labs
- Ventilation Rates for Chemical Laboratories
- Ventilation rates for Storage areas
- Room Supply Air
- Supply Air Quality and Filtration
- Room and Duct Pressurization
- Human Occupancy, Room Temperature and Humidity
- Animal Rooms Room Temperature and Humidity
- Load Calculations
- Room Sound Level and Vibration
- Emergency Control Provisions
- Energy Conservation
- Monitoring
- Maintenance
- Periodic Inspection and Testing
- Periodic Inspection and Testing - Canada
- Test Records
- Management
- Exhaust Systems
- Configuration
- Leakage
- Components
- Manifolded Systems
- Air Velocity
- Stack Height and Discharge Location
- Operational Reliability
- Recirculated Air and Cross Contamination
- Materials and Fire Protection
- Commissioning
- Commissioning - Canada
- Referenced Publications
Biological Laboratories
Siemens Industry, Inc. 85
Term Definition Commentary
Biological
Safety
Cabinets and
Classifications
(Continued)
Class II Cabinets
The Class II cabinets provide protection to personnel, product and the environment.
The cabinets feature an open front with inward airflow and HEPA-filtered recirculated
exhaust air.
The Class II Type A1 cabinet has a fixed opening with a minimum inward airflow
velocity of 75 fpm. The average downward velocity is established by the
manufacturer and is typically 50 to 80 fpm. The Class II Type A1 cabinet is suitable
for use with agents meeting Biosafety Level 2 criteria (DHHS 1999), and, if properly
certified, can meet Biosafety Level 3. However, because approximately 70% of the
airflow is recirculated, the cabinet is not suitable for use with flammable, toxic, or
radioactive agents.
The Class II Type A2 cabinet maintains an inward airflow velocity of 100 fpm and is
similar in performance to the Class II Type A1.
The Class II Type B1 cabinet has a vertical sliding sash and maintains an inward
airflow of 100 fpm at a sash opening of 8 inches. The average downward velocity of
the internal airflow is typically 50 to 80 fpm. The Class II Type B1 cabinet is suitable
for use with agents meeting Biosafety Level 3. Approximately 70% of the internal
airflow is exhausted through HEPA filters; this allows the use of biological agents
treated with limited quantities of toxic chemicals and trace amounts of radionuclides,
provided the work is performed in the direct exhaust area of the cabinet.
The Class II Type B2 cabinet maintains an inward airflow velocity of 100 fpm through
the work opening. The cabinet is 100% exhausted through HEPA filters to the
outdoors. All downward airflow is drawn from the laboratory or other supply source
and is HEPA filtered before being introduced into the workspace. The Class II Type
B2 cabinet may be used for the same level of work as the Class II Type B1 and is
used when the primary consideration is protection of the material inside the hood. In
addition, the design permits use of small quantities of toxic chemicals and
radionuclides in microbiological studies.
In Class II Type A2 cabinets, exhaust air delivered to the outlet of the cabinet by
internal blowers must be handled by the laboratory exhaust system. This
arrangement requires a delicate balance between the cabinet and the laboratory’s
exhaust system, and it may incorporate a thimble connection between the cabinet
and the laboratory exhaust ductwork. Thimble (or canopy) connections incorporate
an air gap between the biological safety cabinet and the exhaust duct. The purpose
of the air gap is to buffer the effect of any exhaust system fluctuations on the
biological safety cabinet airflow. The exhaust system must pull more air than is
exhausted by the biological safety cabinet to make air flow in through the gap. The
designer should confirm the amount of air to be drawn through the air gap. A
minimum flow is required to provide the specified level of containment, and a
maximum flow cannot be exceeded without causing an imbalance through aspiration.
In the event of an exhaust system failure, the air gap allows the cabinet to maintain
safe intake velocity by exhausting HEPA-filtered air through the air gap.
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