GB978003A - Apparatus for the control of airflow in ventilating installations - Google Patents

Abstract

978,003. Ventilators. NOBO FABRIKKER A.S. Aug. 8, 1962, No. 30389/62. Heading F4V. [Also in Division G3] The quantity of air flowing through a ventilating duct 4 is regulated automatically by a mat 7 of permeable material such as foam plastic, foam rubber, or felt, extending across the duct, the mat being of generally wedge-shaped form and being supported by supporting means 6. When the pressure differential across the mat 7 increases the sections of the mat are deflected as indicated by the dotted lines so that portions of the respective surfaces contact each other, thus restricting the area of the mat available for through-flow of air which is thereby maintained at a constant value. A screw adjustment 8 allows the mat to be tightened or slackened to vary the throughflow of air at any given pressure differential. In modifications, the mat is formed with a number of wedge-shaped sections (Fig. 3, not shown), or is conical in form (Fig. 4, not shown). In a further modification (Fig. 5, not shown), deflection of the mat alters the line of contact with inclined impermeable backing members to vary the through-flow area. The backing members may themselves be adjustable in position to alter the volume of air flow at a given pressure differential. Specification 863,937 is referred to.