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
Ventilation Systems
Siemens Industry, Inc. 105
Topic Requirement(s) Commentary
Room and
Duct
Pressurization
U.S. OSHA, 29 CFR, Part 1910, Occupational Safety and Health Standards,
Subpart Z, Toxic and Hazardous Substances,1910.1450,C4:
4. Ventilation - direct air flow into the laboratory from non-laboratory areas and out to
the exterior of the building.
National Fire Protection Association, Standard NFPA 45,2011
8.3.4 The air pressure in the laboratory work areas shall be negative with respect to
corridors and non-laboratory areas of the laboratory unit except in the following
instances:
(1) Where operations such as those requiring clean rooms preclude a negative
pressure relative to surrounding areas, alternate means shall be provided to prevent
escape of the atmosphere in the laboratory work area or unit to the surrounding
area.
(2) The desired static pressure level with respect to corridors and non-laboratory
areas shall be permitted to undergo momentary variations as the ventilation system
components respond to door openings, changes in chemical fume hood sash
positions, and other activities that can for a short term affect the static pressure level
and its negative relationship.
(3) Laboratory work areas within a designated hazardous electrically classified area
with a positive air pressure system as described in NFPA 496, Standard for Purged
and Pressurized Enclosures for Electrical Equipment, Chapter 7, Pressurized
Control Rooms.
8.4.4 Air exhausted from laboratory units and laboratory work areas in which
chemicals are present shall be continuously discharged through duct systems
maintained at a negative pressure relative to the pressure of normally occupied
areas of the building.
(Continued on Next Page)
Note that in most cases, the standards do not
set a pressurization level and generally do not
specify a method to regulate it.
A target in the vicinity of 0.01 inwc to 0.03
inwc (2 Pa to 7 Pa) is often effective in
chemical laboratories. Higher levels are used
in special cases, but this requires especially
tight sealing of the room envelope.
Only AIHA Z9.5 discusses the method of
pressurization. It explains that controlling a
flow offset is usually preferable to controlling
the pressure difference. This is largely
because of the practicality of measuring the
physical quantities. The low room pressure
signal is more easily disrupted than the
stronger air flow signals measured in the
ducts. The flow offset also tends to behave
better when the door is opened than a room
pressure controller.
Note: For additional information on room
pressurization as well as a detailed
explanation of static pressure, velocity
pressure, total pressure, pressurization
control and related parameters refer to
Siemens’ publication Room Pressurization
Control Applications Guide (125-2191).