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
Centralized Exhaust Systems with Constant Volume Fans
General System Applicability
Centralized exhaust systems, similar to Figure 5, that discharge into a single vertical
exhaust stack are applicable to smaller and medium sized laboratory facilities. The
system must be designed so it is capable of maintaining the desired negative static
pressure level within the exhaust system at the maximum required exhaust airflow.
Therefore, the fans must be selected based upon their characteristics as derived
from certified operational test data provided by the fan manufacturer. Normally there
is no need to control the airflow velocity in the exhaust stack since the fans discharge
a relatively constant volumetric airflow through the stack. The stack diameter is
selected to handle the volumetric airflow provide the required exit velocity at the point
of discharge for the normal quantity of air being exhausted. (Additional information on
stack diameters is provided under the Exhaust system stacks - height, location and
exit velocity section.)
Centralized Exhaust Systems Using Variable Air Volume Fans
Larger laboratory facilities, particularly those with variable air volume ventilation
systems would probably best be served by a variable air volume central exhaust
system arrangement. Such exhaust system configurations are especially applicable
when there will be a large volumetric exhaust airflow and also a large variation in the
amount of facility exhaust throughout the occupied time of the day.
CONTROLLER
OUTSIDE AIR
BYPASS DAMPER
STATIC PRESSURE SENSOR
ISOLATION
DAMPER
AIRFLOW
PROOF
SWITCH
VARIABLE
SPEED
DRIVE
ROOF
LABORATORY
EXHAUST
EXHAUST
PLENUM
Figure 6. Centralized Exhaust System Arrangement with Multiple Variable Air Volume
Fans Discharging into Individual Exhaust Stacks.
Siemens Building Technologies, Inc. 29