scope:

Introduction

Fans, duct systems, duct elements (such as filters and coils), dampers, and actuators all work together to control airflow. This text provides resources for building good judgment of the engineering principles needed to size, select, install, and adjust control dampers. Mechanical designers; mechanical and control contractors; and testing, adjusting, and balancing (TAB) contractors are the target audience of this book. Each specializes in a different part of the heating, ventilating, and air-conditioning (HVAC) system. Some material presented here is already familiar to each of these groups, and some material falls outside their normal areas of concern. For example, the information on loss coefficients and pressure loss is basic to the mechanical engineer; however, it is unfamiliar to most control contractors. Much of the subject material bridges gaps that exist between disciplines. The gaps observed in air systems are as follows:

• Lack of understanding of the final control element-the damper

• Lack of understanding of the detailed methods of the other trades on a project

• Lack of understanding of the complexity of airflows

There are many articles published regarding, for example, indoor air quality (IAQ) that say what actions to take. However, there are few suggestions for how they should be taken. This book addresses how to apply dampers within systems to achieve clearly defined goals. The control of airflow in any commercial building is necessary for a variety of functions:

• Temperature control

• IAQ (ventilation)

• Envelope pressure control (mold and infiltration control)

• Elevator door operation

• Exterior door operation

•Exhaust Makeup air

• Pressure cascade from one zone to another

• Mitigation/control of chemical, biological, and radiological (CBR) release

• Smoke containment using shaft and wall dampers

• Smoke control using pressure differentials

• Atria and large-space smoke extraction

• Stairwell pressurization

• Egress corridor smoke control

• Zone smoke control

Fans and dampers are the primary control devices for airflow management. Fans are adequately covered in many available technical publications, such as those published by the Air Movement and Control Association (AMCA 2002). However, this is the first book written about dampers. Many articles and manufacturer bulletins exist, and product information is available from manufacturers, but nothing is comprehensive.

The principles explained are applicable to all damper applications. Fire and smoke control texts offer good insight into airflow strategy and tactics and are sources of information not available elsewhere. For more information, see Chapter 16.