The document discusses Dwyer Instruments damper actuators models DDA, DDC, DDB, and DDD, outlining their key features such as torque range and control options. It also provides examples of applications for damper actuators in variable air volume boxes and air handlers for building automation systems. Contact information is provided for ordering catalogs or for more information on Dwyer Instruments damper actuators.

1. Damper
Actuators
The materials included in this compilation are for the use of Dwyer Instruments, Inc. potential customers and
current employees as a resource only. They may not be reproduced, published, or transmitted electronically
for commercial purposes. Furthermore, the Company’s name, likeness, product names, and logos, included
within these compilations may not be used without specific, written prior permission from Dwyer
Instruments, Inc.
©Copyright 2011 Dwyer Instruments, Inc.

2. Topics
Key Selling Features (DDA, DDC, DDB, DDD)
Applications
Questions

3. DDA
Direct Mounted
17-70 in-lb (2-8Nm)
Actuator Travel
Indicator
Magnetic Clutch
Overload Protection

4. DDA
Push Button Manual
Override
Floating Control
signal on the DDA
Life expectancy of
60,000 cycles
Adjustable angle of
rotation up to 95
degrees

5. DDC
Direct Mounted
17-70 in-lb (2-8Nm)
Actuator Travel Indicator
Magnetic Clutch
Overload Protection
Push Button Manual
Override

6. DDC
Modulating 4-20mA or
0-10 VDC control
Position feedback signal
Life expectancy of
60,000 cycles
Adjustable angle of
rotation up to 95 degrees

7. DDA and DDC

8. DDB
Direct Mounted
Thru shaft design
88-265 in-lb (10-
30Nm)
Actuator Travel
Indicator
Magnetic Clutch
Overload Protection

9. DDB
Push Button Manual
Override
Floating Control
signal on the DDB
Life expectancy of
60,000 cycles
Adjustable angle of
rotation up to 95
degrees

10. DDD
Direct Mounted
Thru shaft design
88-265 in-lb (10-
30Nm)
Actuator Travel
Indicator
Magnetic Clutch
Overload Protection

11. DDD
Push Button Manual
Override
Modulating 4-20mA or
0-10 VDC control
Position feedback signal.
Life expectancy of
60,000 cycles
Adjustable angle of
rotation up to 95 degrees

12. DDB and DDD

13. Applications
Damper Control in Building Automation
Systems
Air Handlers
VAV Boxes

15. VAV Boxes
A VAV (variable air volume)
box controls the air addition
to a room or zone depending
on temperature
A damper inside the VAV
box controls the airflow
A damper actuator
modulates the damper
according to temperature

16. VAV Box with Reheat
Application with an
actuator controlling
the damper and
giving position
feedback

17. VAV Box In a BAS System
Negative
Pressure Room
Has VAV Box
on air inlet

18. Bypass Dampers
A Bypass Damper is
a pressure relief valve
placed between the
supply and return
ducts of the forced
air duct work.

19. Bypass Dampers
As Zone dampers start closing,
the bypass damper will open
and divert some of the supply
air to the return.
This prevents a pressure
buildup in the supply duct
which can cause fan cavitation,
excessive air velocities, and
excessive zone damper blow-
by

20. Air Handlers
The air handler decides how much air to reuse,
bring in new, and exhaust in a building
Dampers control the airflow through the air
handler
Return Air from the building
Outside Air from outside the building
Exhaust Air from the building and exhausted to
outside

22. Questions
To order a free catalog or for more information contact;
Dwyer Instruments, Inc., P.O. Box 373,
Michigan City, IN., 46361
Telephone: (800) 872-9141 or (219) 879-8000
Fax: (219) 872-9057
Internet address: www.dwyer-inst.com
E-mail: info@dwyer-inst.com