Blade dampers are structures consisting of thin metal plates used to stop or regulate airflow inside air handling equipment such as ducts, chimneys, and HVAC systems. They are primarily necessary to ensure air handling systems run smoothly and efficiently.
There are typically two different types of blade dampers used to modulate airflow: parallel blade and opposed blade dampers. While these two systems have the same function, they perform differently, making each suited for applications with different requirements.
Learn more about the mechanics of each blade damper and their benefits for specific industrial applications.
Parallel Blade Dampers
Parallel blade dampers are designed in a way so that the blades move in the same parallel direction when opened. This synchronized movement resembles a standard window louver. On a graph displaying the relationship between flow rate and position of the blades, a parallel blade damper has a steep, aggressive flow rate once it begins to open. This means the air volume passing through the ductwork increases rapidly as the blades transition from closed to open.
This specific design makes these units cost-effective to manufacture and simple to operate. They perform best in HVAC applications requiring volume control between wide open and 75% open or simple open-close operation. Because the airflow responds readily to parallel blade movement, small adjustments to the blade angle yield significant airflow changes within the building.
Opposed Blade Dampers
Opposed blade dampers have the blades moving in opposing directions from one another. This alternating mechanical movement creates a distinct airflow profile inside the duct. On a graph showing the relationship between flow rate and blade position, opposed blade dampers exhibit a shallow curve upon first opening. Airflow increases slowly and steadily as the blades open.
The steady flow characteristics make this unit effective for precise airflow modulation. Facility managers select these specific models when they need exact volume control spanning from fully open to 25% open. The opposed motion also directs the air straight down the duct, minimizing turbulence immediately downstream of the unit.
Applications of Each Type
System engineers must match the damper blade configuration to the exact HVAC requirements. Selecting the wrong style can result in inefficient temperature regulation and/or wasted system energy.
Consider the following when selecting between parallel blade vs. opposed blade dampers.
- Open and close functions. Parallel blade designs excel at simple open-close operations. Engineers deploy them for heavy exhaust fans or basic air intake vents where fine-tuning is unnecessary. Due to their less even airflow, parallel blade dampers are not recommended for installation upstream of critical components.
- Precise flow modulation. Opposed blade designs maintain steady air distribution across the entire duct face. Technicians install them in complex air supply systems requiring exact volume adjustments downstream of the damper to balance building temperatures.
Parallel Blade Dampers from Alan Manufacturing
Alan Manufacturing, Inc. brings decades of custom damper manufacturing experience to every HVAC project. Our team manufactures standard components alongside completely custom airflow solutions. We have designed over 1,000 distinct products to solve complex industrial challenges.
One of our parallel-blade damper products is the Motorized Rectangular Shutter Volume Damper, which comes in a variety of dimensions and has been tested to 250,000 cycles. Each blade features PTFE bushings for quieter and smoother operation. The damper is available with multiple control options, including manual, pneumatic, and electric actuation, to match your installation requirements. It installs easily via the included mounting plate.
We offer manual and motorized damper equipment to match your project’s demands for:
Custom Sizing
Our technicians can fabricate hardware to fit unique duct dimensions.
Control Options
We construct manual levers, motorized actuators, and specialized wireless remote control systems.
Volume Pricing
We fulfill high-volume production runs with significant pricing benefits for large-scale commercial or industrial installations.
Rapid Fulfillment
Our facility targets standard lead times of 7–10 business days to keep your project on schedule.
Contact Alan Manufacturing to Learn More
Alan Manufacturing, Inc. operates as a custom manufacturer of specialized HVAC components for the commercial and industrial markets. We build precise HVAC zone control systems, duct mufflers, motors and actuators, and custom dampers to meet exact airflow specifications. Our team supplies dependable hardware to engineers and project managers across the United States and Canada.
Contact our team to discuss your specific airflow challenges, or request a quote to start your HVAC damper project.