Metering dispenser

Claim 2

A dispenser, comprising: (A) a container for containing fluid to be dispensed; (B) a metering valve connected to said container, said metering valve comprising: (a) a metering chamber; (b) a valved inlet for introducing a metered dose of the fluid into said metering chamber when said valved inlet is open; and (c) a valved outlet for dispensing the metered dose from said metering chamber when said valved inlet is closed; and (C) a barrier for pressurizing the fluid so that substantially no vapor or gas remains within said metering chamber when said valved inlet is open.

Claim 3

The dispenser of claim 1, wherein said barrier is formed of a flexible gas-impermeable bag, said bag being connected to said container, said bag and said container defining a first chamber for containing the fluid to be dispensed and a second chamber for containing a second fluid or gas at a pressure sufficient to compress the fluid to be dispensed so that substantially no vapor or gas exists within said first chamber.

Claim 4

The dispenser of claim 1, wherein said barrier is formed of an expandable bag enclosed within said container, said expandable bag containing vaporizable fluid or gas for pressurizing the fluid to be dispensed.

Claim 5

The dispenser of claim 1, wherein said barrier is formed of a slidable piston for pressurizing the fluid to be dispensed.

Claim 6

The dispenser of claim 1, wherein said metering valve is a large-dose metering valve, and said metering chamber has a volume of not less than about 200 microliters.

Claim 7

The dispenser of claim 5, wherein said metering chamber has a volume of not less than about 500 microliters.

Claim 8

A dispenser, comprising: (A) a container containing fluid to be dispensed; (B) a metering valve connected to said container, said metering valve comprising: (a) a metering chamber; (b) a valve stem extending through said metering chamber; (c) a first passageway for introducing a metered dose of said fluid into said metering chamber when said valve stem is in a first position; (d) a second passageway for dispensing the metered dose from said metering chamber when said valve stem is in a second position; (e) means for closing said first passageway when said valve stem is in said second position; (f) means for closing said second passageway when said valve stem is in said first position; and (g) means for biasing said valve stem toward said first position; and (C) pressurizing means for pressurizing said fluid to be dispensed so that substantially no vapor or gas remains within said metering chamber when said valve stem is in said first position, said pressurizing means including pressurizing fluid and a barrier for separating said fluid to be dispensed from said pressurizing fluid, the pressure of said pressurizing fluid being greater than the vapor pressure of said fluid to be dispensed.

Claim 9

A dispenser, comprising: (A) a container containing fluid to be dispensed; (B) a metering valve connected to said container, said metering valve comprising: (a) a metering chamber; (b) a valve stem extending through said metering chamber; (c) a first passageway for introducing a metered dose of said fluid into said metering chamber when said valve stem is in a first position; (d) a second passageway for dispensing the metered dose from said metering chamber when said valve stem is in a second position; (e) means for closing said first passageway when said valve stem is in said second position; (f) means for closing said second passageway when said valve stem is in said first position; and (g) means for biasing said valve stem toward said first position; and (C) pressurizing means for pressurizing said fluid to be dispensed so that substantially no vapor or gas remains within said metering chamber when said valve stem is in said first position, said pressurizing means including pressurizing fluid and a barrier for separating said fluid to be dispensed from said pressurizing fluid, the pressure of said pressurizing fluid being greater than the vapor pressure of said fluid to be dispensed.

Claim 10

The dispenser of claim 7, wherein said metering valve is a large-dose metering valve.

Claim 11

The dispenser of claim 7, wherein said metering chamber includes a rigid wall, an elastomeric wall for supplementing the volume defined by said rigid wall, and an opening through said rigid wall for communicating with the volume defined by said elastomeric wall.