| 摘要 |
A pressure relief vent 2 comprising at least one vent blade 6 rotatably mounted in a vent housing 4 about first and second spaced apart pivot axes 8, 14 located on a pivot mechanism 10, the vent including a spring 18 attached to the pivot mechanism to urge the blade towards a first position in which the blade cooperates with the housing and any adjacent blades to close the vent (see Figs. 1, 4), the blade rotatable in the same rotational direction about each respective pivot axis to second and third positions in which the vent is open (see Figs. 2, 3, 5), in response to a negative or positive differential air pressure across the vent. Each blade may have a weight in the form of solid steel bar (39, Fig. 4) located at the top edge (when closed) to aid rotation against the spring. A pivot pin 8 mounted on each blade may be moveable along an accurate guide slot in the housing as the blade pivots about the other pivot axis 14. Blades may overlap to prevent flame propagation when closed. |
