Pressurized dispencer with controlled release of stored reserve propellant

Abstract

A gas storage and delivery system for restoring pressure as it is depleted from a pressurized container stores a reserve supply of propellant gas on a gas-adsorbing material. The propellant gas is released into the container in response to a decrease in pressure in the container to maintain a desired pressure as product is depleted. The gas-adsorbing material is wetted with a non-polar release-promoting agent to promote release of the sorbed gas in response to decreases in pressure in the container and to ensure that substantially all of the sorbed gas is obtained if needed in response to decrease in pressure in the container.

1 . A gas storage and delivery system for restoring pressure as it is depleted from a pressurized container, comprising:
 a container holding a product under pressure to be dispensed from the container, said container having a normally closed discharge valve through which said product is dispensed when the valve is opened;   a quantity of propellant comprising a gaseous material under pressure in the container, occupying a space in the container and applying to the product a predetermined pressure of from about 30 to about 180 psig to discharge product from the container when the valve is opened;   a quantity of gas-adsorbing material in the container;   a reserve supply of gaseous material adsorbed on the gas-adsorbing material, said reserve supply of gaseous material being desorbed from the gas-adsorbing material and released into the container in response to a decrease in pressure in the container, thereby restoring and maintaining a predetermined pressure in the container as product is depleted from the container; and   wherein said gas-adsorbing material is wetted with a non-polar release-promoting agent to promote release of the sorbed gas in response to decreases in pressure in the container, and wherein release of substantially all of the sorbed gas is obtained if needed in response to decrease in pressure in the container.   
     
     
         2 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the gas adsorbing material is selected from the group consisting of activated carbon, natural or synthetic zeolite, alumina, and a carbon fiber composite molecular sieve.   
     
     
         3 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the gaseous material is selected from the group consisting of carbon dioxide and nitrous oxide.   
     
     
         4 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the gas adsorbing material is in the form of a one-piece cohesive body of material that retains its shape in the container and prevents dispersal of the material throughout the product.   
     
     
         5 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the gas adsorbing material is a granular or powdered material.   
     
     
         6 . A gas storage and delivery system as claimed in  claim 5 , wherein:
 a film or membrane cover is placed around the gas adsorbing material to prevent dispersal of it into the product but to enable flow of the stored gaseous material from the gas adsorbing material into the product.   
     
     
         7 . A gas storage and delivery system as claimed in  claim 6 , wherein:
 the film or cover prevents contact between the gas adsorbing material and the product.   
     
     
         8 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the non-polar fluid comprises mineral spirits; and   the non-polar fluid is added to the container in the ratio of from about 10% to about 90%, by weight, of non-polar fluid to adsorbent material.   
     
     
         9 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the non-polar fluid comprises isoparaffin; and   the non-polar fluid is added to the container in the ratio of from about 10% to about 90%, by weight, of non-polar fluid to adsorbent material.   
     
     
         10 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the sorbent material is contained within an envelope made of a material that is impermeable to the propellant gas and to moisture vapor and to the product to be dispensed, said envelope being perforated to enable passage therethrough of the sorbed gas and product but precluding passage therethrough of the sorbent.   
     
     
         11 . A gas storage and delivery system as claimed in  claim 10 , wherein:
 the envelope material comprises a heavy foil laminated with a polyethylene film.   
     
     
         12 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the sorbent is sealed in a gas-permeable membrane that permits passage of the gaseous material but precludes passage of the product.   
     
     
         13 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the propellant comprises carbon dioxide and is placed in the container in the form of dry ice that melts to form the gaseous propellant and pressurize the container.   
     
     
         14 . A gas storage and delivery system as claimed in  claim 1 , wherein:
 the sorbent is loaded with propellant gas and pre-wetted with the non-polar fluid prior to being placed in the container.   
     
     
         15 . A process of filling and pressurizing a dispensing container for dispensing a product pressurized by a propellant gas in the container, comprising the steps of:
 placing a desired quantity of gas-adsorbing material in the container;   wetting the sorbent with a non-polar fluid;   closing and sealing the container;   pumping a predetermined quantity of propellant gas into the container; and   injecting product into the container.   
     
     
         16 . A process of preparing a dispensing container for dispensing product under pressure from a pressurized gaseous propellant, comprising the steps of:
 placing a gas-adsorbing material in a storage container or drum flooded with a propellant gas at substantially atmospheric pressure and temperature so that the sorbent material can be stored and shipped in bulk quantities to a point of use without becoming contaminated and gas adsorbed on the sorbent is not desorbed;   at a filling location placing a desired quantity of the sorbent in a dispensing container to be pressurized with the propellant gas and filled with product;   closing and sealing the dispensing container and pumping additional propellant gas into the dispensing container so that a desired pressure is achieved when product is added later; and   adding product to the container and shipping the filled and pressurized container to a point of sale or use.   
     
     
         17 . A process as claimed in  claim 16 , wherein:
 the sorbent is pre-wetted with a non-polar fluid before it is placed in the dispensing container.   
     
     
         18 . A process as claimed in  claim 16 , wherein:
 the sorbent is wetted with a non-polar fluid after the sorbent is placed in the dispensing container by injecting an appropriate amount of the non-polar fluid into the container and into contact with the sorbent.   
     
     
         19 . A process as claimed in  claim 16 , wherein:
 the sorbent is wetted with a non-polar fluid prior to placing it in the storage container.