Page 45 - Industrial Ventilation Design Guidebook

1 0 CHAPTER 2 TERMINOLOGY
A controlled zone is a zone in which the thermal and air purity (quality)
conditions are controlled to their specified levels. The two categories of con-
trolled zones are as follows:

• The main controlled zone is normally a large area, which is often the
same as the occupied zone.
• A local controlled zone is an area where the air is controlled locally; the
control requirements may be for worker protection and comfort, for
process control, or for production protection.
An uncontrolled zone is a zone in which the thermal and air purity (qual-
ity) conditions are not specified or controlled.
Note: There may also be uncontrolled zones near
to the processes inside the main controlled zone.
Capture zones are zones in which source emissions will be captured by a
source-capturing system, and where the capture efficiency is determined and
shall be maintained over the working period. From the pollutant concentra-
tion point of view, the capture zone is uncontrolled (e.g., workers shall not en-
ter a capture zone without additional protection).

2.1.2 Industrial Air Conditioning Systems

According to Chapter 1, industrial air technology includes measures for in-
door environments (general and local); measures to prevent harmful emissions
from industrial processes from being discharged outdoors, such as conveying
and cleaning technologies; and measures to prevent or minimize damages
caused by accidents, fire, or explosion.

2.1.2.1 Air Conditioning Systems
Room air conditioning (see Fig. 2.1) systems are used to control the main
controlled zone. Systems can be divided into subsystems, e.g.:
• Air-handling systems
• Air distribution systems (ductwork)
• Room air distribution systems
• Ventilation systems
• Room heating and cooling systems
• Main exhaust systems
• Discharge systems: stacks, environmental dispersion

Note: Air distribution systems are not ventilation or air conditioning
systems. For example, mixing air distribution and displacement air
distribution are methods to bring the supply air to the treated space.
Discharge systems are used to discharge exhaust air to the outdoors in such a
way that harmful spreading of pollutants to the environment and back indoors
is avoided.