Pressure Relief Dampers
Backdraft dampers with adjustable start-open pressure.
Pressure Relief Dampers
Backdraft dampers with adjustable start-open pressure.

Pressure relief dampers are backdraft air dampers with an adjustable start-open pressure. This provides the capability of maintaining a relative constant pressure at various airflows. The damper closes when there is a decrease in differential pressure. This damper is generally used as a safety or controlling device. For example, mounting this damper on a duct section would relieve unexpected overpressure or relieve negative pressure downstream of a rapidly closing fire damper.

HPR-120
HPR-120
2V blades; pressure relief 0.1 to 2 in. wg; back pressure of 5 to 8.5 in. wg; velocity up to 5,150 fpm and temperatures from -20°F to 250°F.
https://catalog-api.greenheck.com/api/product/en-us/seo/hpr-120
HPR-230
HPR-230
Fabricated airfoil blades; pressure relief 0.25 to 4 in. wg; back pressure of 6 to 13.5 in. wg; velocity up to 5,150 fpm and temperatures from -40°F to 250°F.
https://catalog-api.greenheck.com/api/product/en-us/seo/hpr-230
HPR-330
HPR-330
Fabricated airfoil blades; pressure relief 0.5 to 6 in. wg; back pressure of 13.5 to 20 in. wg; velocity up to 6,400 fpm and temperatures from -40°F to 250°F.
https://catalog-api.greenheck.com/api/product/en-us/seo/hpr-330