Grilles, Registers and Diffusers FAQs
Per the mechanical code, the requirement is a 200lb load applied to a 2" disc at the most critical area of a floor register. All of our registers (utility and decorative) meet or exceed this requirement. Our most robust model would be the 210/265 models.
Effective area, Ak, is the net area (in square feet) of a grille utilized by the area stream in passing through the face openings. It is used in the equation: CFM= Face Velocity* Effective Area. This is used in our engineering data tables.
Free area is the total minimum area of the openings in the supply outlet or return inlet (usually in square inches) through which air can pass. Also known as the "see-through area". (See also "effective area"). The free area should NOT be used to determine the amount of air that can pass thru the grille when it's being forced thru by a fan. Free area only applies to natural (gravity) air transfer thru the grille (i.e. combustion air into an appliance room).