What You Need to Know Before Starting

• Will the damper be used to provide intake or exhaust air for an HVAC system? If so, are there pressure drop limitations the damper must meet? Knowing how to use the blast damper manufacturer’s performance data to calculate or estimate pressure drop based on damper size will be important.
• Will the damper be used as a vent to allow air circulation or for venting an inert gas fire suppression system? If so, have minimum free vent areas been specified for the dampers? Will the blast damper manufacturer share the free vent areas for their dampers to help you size the damper?
• What is the blast load that the damper must withstand? In general, damper blast load integrity is a function of damper width (or blade width). Therefore, high blast load protection (1 bar and greater) may require sectional dampers or multiple dampers to withstand the blast load. This may increase pressure drop or decrease free vent area. Also, is there a minimum pressure upon which the damper must close to provide the appropriate protection?
• In what type of ambient environment will the damper be used? Will the damper be installed in a hazardous environment or an explosive atmosphere? Is ATEX or an equivalent certification required? Will the damper need to be fabricated in stainless steel to withstand a caustic or marine environment? MAT’s model BL-201 blast damper is ATEX certified for explosive atmospheres. Both our BL-201 and BL-301 models can be fabricated using 300 series stainless steel.
• Will anything be placed directly in front of the damper? If a louver or grille will be placed in front of the damper, what is the likelihood that these items would break apart under a blast load and become lodged between the blast damper blades before the damper closes? MAT can review your application and determine if the blast damper should be configured with a debris grid on the front side to prevent this from happening.

Understanding if the damper needs to withstand multiple blast loads

In order to determine if a blast damper needs to withstand more than one blast load, one must consider the building codes and safety standards, the building site details, and specific application requirements. Blast protection within ventilation systems is becoming increasingly critical as building codes and safety standards evolve. Be sure to understand what the requirements are for your project and review the blast damper manufacturer’s test data to ensure suitability for your application. MAT’s BL-201 Series Rectangular Blast Damper is designed to provide blast protection up to 3 bar and multiple blast load protection up to 1 bar. Our model BL-301 Blast Damper also withstands multiple blast loads up to 1 bar.

Choosing the right mounting configuration

Blast dampers can be vertically surface mounted to exterior walls or horizontally mounted to roof structures, or duct mounted. Surface mounted dampers are typically configured with a mounting plate (or blast plate) to secure the damper to the wall or roof structure. The size of these blast plates varies by manufacturer. Dampers can be installed inside the wall opening or mounted outside the wall opening.

Duct mounted applications do not utilize a blast plate. The dampers are flange mounted to duct connections on both sides of the damper. The duct must be rated to withstand the blast load as well as support the weight of the damper.

Other applications may require the damper to be surface mounted with duct connections on both sides of the damper.

Multiple questions lead to one answer

Selecting a blast damper includes understanding several important factors: the purpose of the damper and the related performance requirements, blast load requirements, ambient environment, and mounting configurations. Just as important, however, is an understanding of building codes, safety standards and reviewing the blast damper manufacturer’s test data to ensure suitability for the specific application. Link here to learn more about understanding blast pressure and here to understand blast damper function.

Ask us how our blast dampers are designed to protect equipment and personnel.

Click to email Grant Gallinger today!