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
Applicable Definitions (Alphabetical Listing)
Siemens Industry, Inc. 15
Term Definition Commentary
Time Weighted
Average
(TWA)
Ventilation System:
CAV and VAV
Ventilation System:
Two State Control
or
Two State CAV
The concentration value of an airborne toxic substance obtained by averaging the
concentration level over a specified period of time.
These are common abbreviations for a Constant Air Volume (CAV) and a Variable Air
Volume (VAV) ventilation system respectively. A CAV system is a fan driven ventilation
system that essentially keeps its airflow at a constant rate and has no provision to
enable varying the airflow rate. It is the most common type of ventilation system and
the least complex to control. A VAV system is a fan driven ventilation system that can
vary the overall airflow rate (normally by automatic controls) to meet the actual airflow
needs of the rooms or spaces served. It is a less common type of ventilation system
and somewhat more complex to control. Both types of systems generally consist of a
supply side that provides conditioned (heated, cooled, humidified or de-humidified) air
and an exhaust side to remove contaminated air. Both types of systems can be
designed for utilization as a laboratory ventilation system.
A two state ventilation system is a CAV system designed to provide two separate levels
of ventilation airflow rather than the one level of an ordinary CAV system. The two
levels typically consist of a higher level of ventilation airflow that is normally used during
regular occupancy periods when research activities in laboratory rooms and the active
use of fume hoods would normally benefit from a higher level of ventilation airflow (Air
Changes per Hour – ACH). The lower level is normally applied when a laboratory room
is unoccupied and therefore a lesser amount of ventilation air is usually sufficient. Two
state CAV systems are utilized for energy efficiency since less ventilation airflow also
requires less heating or cooling. (Also see Ventilation Systems: Ventilation Rates for
Chemical Laboratories and Fume Hoods: Minimum Exhaust.)
CAV ventilation systems are usually less
complex than VAV systems. However, CAV
systems normally consume more energy
because a CAV system has no provision for
reducing airflow to meet reduced ventilation
requirements that typically occur during milder
weather. VAV systems can significantly
reduce energy consumption since they can
provide only the amount of conditioned airflow
needed to meet ventilation requirements
during periods of decreased demand.
To use Two-state CAV systems, all CAV fume
hoods in a laboratory room must have their
sashes closed when the room is unoccupied
so both the room supply airflow and the fume
hood exhaust airflow can be reduced. The
CAV system controller must receive
confirmation that all fume hood sashes are
closed (usually by sash position switches)
before the unoccupied ventilation mode can
be initiated. Laboratory personnel must be
sure to close all sashes at the end of the
occupied period. Laboratory rooms that have
long unoccupancy periods (such as academic
teaching labs) will receive the greatest benefit
from a Two-state CAV System.