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US 4,355,764 AGranted
Low capacitance airless spray apparatus
AssigneeNordson Corporation
InventorsAlvin A. Rood, Donald R. Hastings
Life of this patent
Estimating the term…
Abstract
An airless electrostatic spray gun for atomizing and electrostatically depositing liquid coating materials onto substrates. The gun is characterized by a low capacitance which enables the electrode of the gun to be shorted to a grounded object without the resulting spark having sufficient energy content to ignite the surrounding atmosphere.
Claims19
An airless electrostatic spray apparatus comprising,
- an elongated body of insulating material having two passages therethrough,
- one of said passages being adapted to be connected with a supply of liquid coating material under sufficient pressure to effect airless atomization of said liquid coating,
- valve means for controlling flow of liquid coating material through said one passage,
- electrical circuit means including electrical resistor means in the other of said passages, said circuit means being adapted to be connected to a source of electrical potential, and
- a nozzle assembly comprising
- a nozzle mounting ring of insulative material having an axial passage therethrough, said axial passage of said nozzle mounting ring being coaxially aligned with said one passage of said elongated body,
- a nozzle support adapter, said adapter having an axial passage therethrough and being mounted within said axial passage of said mounting ring, said adapter being a single unitized piece of electrically conductive material,
- an electrically conductive airless spray nozzle, said nozzle being fixedly mounted within said axial passage in said adapter,
- electrically non-conductive sealing means operable between said adapter and said elongated body, and
- an electrode mounted within said nozzle mounting ring, said electrode being electrically connected to said electrical circuit means but electrically insulated from said electrically conductive nozzle,
- the mass of said electrically conductive nozzle and nozzle support adapter being sufficiently small and having a sufficiently low capacitance that there is no tendency for electrical current in said circuit means to arc between said electrode and said nozzle or nozzle support adapter and being sufficiently low in capacitance that any spark generated between said nozzle assembly and a grounded object is of a minimal safe energy level.
8 more elements
An airless electrostatic spray apparatus comprising,
- an elongated body of insulating material having two passages therethrough,
- one of said passages being adapted to be connected with a supply of liquid coating material under sufficient pressure to effect airless atomization of said liquid coating,
- valve means for controlling flow of liquid coating material through said one passage,
- electrical circuit means including electrical resistor means in the other of said passages, said circuit means being adapted to be connected to a source of electrical potential,
- a nozzle mounting ring of insulative material having an axial passage therethrough, said axial passage of said nozzle mounting ring being coaxially aligned with said one passage of said elongated body,
- a nozzle supporting adapter having an axial passage therethrough and being mounted within said axial passage of said mounting ring, said adapter being a single unitized piece of electrically conductive material,
- an electrically conductive airless spray nozzle, said nozzle being mounted within said axial passage in said adapter,
- electrically non-conductive sealing means operable between said adapter and said elongated body, said sealing means comprising a double conical sealing plug, said plug having a first end tapered portion tapered in a first direction engaged with a substantially correspondingly tapered portion of said one passage in said elongated body, and a second end tapered portion tapered in an opposite direction and engaged with a substantially tapered portion of said axial passage of said adapter, and
- an electrode mounted within said nozzle mounting ring, said electrode being electrically connected to said electrical circuit means,
- the mass of said electrically conductive nozzle and nozzle support adapter being sufficiently small and having a sufficiently low capacitance that there is no tendency for electrical current in said circuit means to arc between said electrode and said nozzle or nozzle supporting adapter and being sufficiently low in capacitance that any spark generated between said nozzle or nozzle supporting adapter and a grounded object is of a minimal safe energy level.
7 more elements
An airless spray apparatus comprising,
- an elongated body having a central passage therethrough,
- said passage being adapted to be connected with a supply of liquid coating material under sufficient pressure to effect airless atomization of said liquid coating,
- valve means for controlling flow of liquid coating material through said one passage,
- a nozzle mounting ring of insulative material having an axial passage therethrough, said axial passage of said nozzle mounting ring being coaxially aligned with said passage of said elongated body,
- a nozzle supporting adapter, said adapter having an axial passage therethrough and being mounted within said axial passage of said mounting ring,
- an airless spray nozzle, said nozzle being mounted within said axial passage in said adapter, and
- a unitary, non-elastomeric sealing means operable between said adapter and said elongated body, said sealing means comprising a double conical plastic sealing plug, said plug having a first end tapered portion tapered in one direction and engaged with a substantially correspondingly tapered portion of said passage in said elongated body, and a second end tapered portion tapered in an opposite direction and engaged with a substantially correspondingly tapered portion of said axial passage of said adapter.
4 more elements
Dependencies are inferred from the claim text.