Importance

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Abstract

The valve has a variable volume chamber (11) of annular section between an outer tubular body (1) and a coaxial member (4). An annular piston (5) is free to move axially to vary the volume of the chamber under the combined forces of a return spring (6) and the pressure in the container. A controllable plunger (7) is subject to the force of a return spring (8) and to control force from a user. In the rest position the plunger leaves the variable volume chamber in communication with the interior of the container, and thus with the substance to be dispensed. When pressed against its return spring (8), the plunger isolates the variable volume chamber from the interior of the container and puts the variable volume chamber in communication with the outside. A pressure difference thus appears across the piston (5) and the piston moves along the variable chamber against the force of its return spring (6) to dispense a measured volume of substance. When the plunger (7) is released, the inside pressure of the container is again applied to both faces of the piston (5), allowing the return spring (6) to refill the variable volume chamber (11) with a further volume of substance to be dispensed.

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First Claim