Basic Documentation
Table Of Contents
- About this Application Guide
- Chapter 1–Introduction
- Chapter 2–Goals of the Laboratory Environment
- Chapter 3–Unique Ventilation Needs of a Laboratory Facility
- Chapter 4–Ventilation Systems Classification
- Chapter 5–Laboratory Facility Exhaust Systems
- Chapter 6–Laboratory Containment Units - Ventilation
- Chapter 7–Room Ventilation, Makeup Air, and Pressurization Control Systems
- Chapter 8–Laboratory Temperature and Humidity Control Systems
- Chapter 9–Laboratory Emergencies - Ventilation System Response
- Chapter 10–Laboratory Ventilation System - Validation
- Chapter 11–Laboratory Ventilation System - Commissioning
- Glossary
- Index
Laboratory Ventilation - Room System Configuration
CHEMICAL
STORAGE
CHEMICAL
STORAGE
SUPPLY
AIR DIFFUSERS
SUPPLY AIR
TERMINAL
PRIMARY
ENTRY / EXIT
ROOM
GENERAL
EXHAUST
FUME HOOD
FUME HOOD
ROOM AIRFLOW
E
X
H
A
U
S
T
S
U
P
P
L
Y
Figure 11. Proper Laboratory Room Ventilation Arrangement.
Supply air should always enter a laboratory room from ceiling air diffusers that are
sufficiently distant from the fume hoods or biological safety cabinets to avoid cross
drafts or air turbulence at the face opening of the fume hoods or biosafety cabinets.
Such turbulence can disrupt the uniform airflow through the face opening that is
necessary to attain containment and protect the user from toxic fumes or airborne
infectious agents. Supply air diffusers that serve a laboratory room should also be
specifically designed ceiling diffusers for laboratory room applications which will limit
the terminal velocity of the supply air entering the room.
Wall mounted supply air diffusers are not normally suitable for laboratory room
ventilation applications since they can create high velocity horizontal room cross
currents at the face opening of the fume hoods or biosafety cabinets. Such cross
currents can have a very adverse effect of the ability of a fume hood or biosafety
cabinet to provide effective containment.
Specifically, the velocity of any room air currents that flow across the open face area
of a containment unit (that is, fume hood or biological safety cabinet) should be no
more than a maximum of 50% of the containment unit face velocity. Aside from using
the appropriate type of supply air diffusers, having multiple ceiling air diffusers in lieu
of a single diffuser will further limit the supply air velocity as it is discharged into the
room.
It is good ventilation design practice to always include at least one room general
exhaust provision for chemical and biological laboratory rooms. Sometimes a room
general exhaust may be required to attain the minimum required room ventilation rate
or enable sufficient supply air for the room to maintain the desired ambient
conditions. However, a room general exhaust is still recommended even if the
amount of room air exhausted by the containment units and other exhaust provisions
is sufficient to meet the room’s ventilation rate and ambient requirements.
Siemens Building Technologies, Inc. 59