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Dispensing apparatus for metered quantities of pressurised fluid

  • US 4,896,832 A
  • Filed: 08/25/1988
  • Issued: 01/30/1990
  • Est. Priority Date: 09/07/1987
  • Status: Expired due to Term
First Claim
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1. Dispensing apparatus for dispensing metered quantities of a pressurized fluid comprising a pressurized dispensing container, a housing for the container defining a bore, the container having a body which is axially slidable in the bore, the container having a collapsible chamber metering valve located at a first end of the body for dispensing metered quantities of fluid and actuated by axial depression of a valve stem defining a dispensing flowpath, a valve actuator fixedly connected to the housing at a corresponding first end there and defining a further dispensing flowpath for product fluid dispensed through the stem, and trigger means operable to urge the container body axially towards the first end of the housing such that the valve stem is depressed by relative movement together of the valve and actuator and thereby dispensing a metered quantity of fluid, wherein the container body defines a chamber and the container includes means dividing the chamber into a product fluid reservoir communicating with the valve and a propellant fluid reservoir, the dividing means being movable such that propellant pressure is applied to the product fluid without mixing of the respective fluids, the dividing means including a free piston axially slidable within the chamber and dividing the chamber into a first portion constituting the product fluid reservoir located forward of the piston and a second portion constituting the propellant fluid reservoir located rearward of the piston, and wherein the piston includes a forward portion of a first material selected to be substantially chemically non-reactive with the product fluid and a rearward portion of a second material selected to be substantially impermeable to the propellant fluid, the piston portions being composited such that the product and propellant fluids respectively do not contact the second and first materials of the piston respectively.

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