Apparatus and method for ligament mode electrostatic spraying
AssigneeImperial Chemical Industries PLC
InventorsAndrew Jeffries, Michael L. Green, Timothy J. Noakes
Life of this patent
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Abstract
Relatively low resistivity liquids are formed into sprays under the influence of an applied electric field acting between a nozzle and the nozzle surroundings which may be at earth potential. The liquid issues from the nozzle as a ligament which undergoes necking to a diameter smaller than that of the nozzle orifice, thereby producing droplets with a volume median diameter less than the orifice diameter.
Claims24
A process for electrostatically spraying liquid having a resistivity less than about 1.times.10.sup.7 .OMEGA. cm and greater than about 1.times.10.sup.4 .OMEGA. cm, comprising the steps of:
- supplying said liquid to a spray head for discharge as a jet through an orifice of the spray head,
- applying a high electrical potential to said spray head so that liquid supplied to the spray head is projected from the orifice under the influence of electrostatic forces, and
- controlling the exit velocity of the liquid jet from the orifice and the potential gradient in the immediate vicinity of the orifice to effect necking of the discharging liquid jet to form a ligament having a cross-sectional dimension substantially smaller than the dimension of the orifice.
A ligament mode electrostatic spraying device for use in spraying liquid, said device including:
- ligament forming means, said ligament forming means comprising
- a spray head having an orifice of a given diameter,
- liquid supplying means for supplying liquid having a resistivity of less than approximately 1.times.10.sup.7 .OMEGA. cm to said orifice and for causing said liquid to be discharged from said orifice as a jet at a given exit velocity,
- potential applying means for applying a high electrical potential to said spray head, for causing said liquid supplied to said orifice to discharge under the influence of electrostatic forces created by said potential applying means, and for establishing, in the immediate vicinity of said orifice, a potential gradient of sufficient magnitude to neck said jet into a ligament;
- wherein said ligament forming means is for forming a ligament having a cross-sectional dimension substantially smaller than the diameter of the orifice.
Dependencies are inferred from the claim text.