GB556583A - Improvements in alarm apparatus operated by air or gas under pressure - Google Patents

Abstract

556,583. Fluid-pressure horns. ABBEY, A. (Kockums Mekaniska Verkstads Aktiebolag). April 8, 1942, No. 4612. [Class 13] Relates to fluid pressure alarms in which a diaphragm 13 or like member controls the passage of fluid from an inlet channel 20 to a sound-producing channel 14 and is actuated on one side by the pressure in both channels and on the other by the pressure in a chamber 12. According to the invention the pressure in the chamber 12 is influenced by the pressure in the channel 14 through a passage having a counterpressure valve. In Fig. 1, the passage is constituted by passages 18 in the wall of the casing, the valve 19 being arranged as shown. In Fig. 2, the diaphragm is loosely mounted so that the passage consists of the clearance between the diaphragm and the wall of the chamber, the valve being constituted by the diaphragm itself. In Figs. 3 to 6 (not shown), the passage consists of an aperture in the diaphragm itself, which aperture may cooperate with a valve seat member, Fig. 3 (not shown), with a flap valve mounted on a leaf spring, Fig. 4 (not shown), with a flat fixed ring, Fig. 5 (not shown), or with a resilient bowlshaped second diaphragm, Fig. 6 (not shown). In Fig. 7 (not shown), the diaphragm is replaced by a tongue fixed at one end only, having an aperture 18 co-operating with a valve as in the other Figures. The chamber 12 has a leakage passage communicating with the atmosphere. Specification 605,774 is referred to.