Hydraulically assisted high volume low pressure air spray gun

A method of performing high volume low pressure air spraying of liquid coating material, comprising the steps of delivering liquid coating material to a spray head;

• emitting the coating material delivered to the spray head from an elongate fluid orifice in the spray head in a flat fan-shaped pattern;
• supplying air to the spray head at a flow rate in excess of 10 CFM at the spray head and at a pressure of no more than 15 psi at the spray head;
• emitting air delivered to the spray head from an atomizing air orifice in the spray head, that encircles the elongate fluid orifice, to break up the flat fan-shaped pattern of coating material into a flat fan-shaped atomized spray and from opposed side port air orifices to impinge jets of air against opposite sides of the spray;
• adjusting the volume flow rate of air emitted from the side port air orifices;
• and, in response to and concurrently with performance of said adjusting step, adjustably controlling the volume flow rate of air supplied to the spray head to prevent the pressure of air at the spray head from exceeding a selected maximum pressure as a result of changes in the volume flow rate of air emitted from side port air orifices.

A hydraulically assisted high volume low pressure air spray coating apparatus, said apparatus comprising a spray head having an elongate fluid orifice, an atomizing air orifice encircling said elongate fluid orifice, and opposed side port air orifices;

• means for delivering liquid coating material to said spray head for emission from said elongate fluid orifice in a flat fan-shaped pattern;
• means for supplying air to said spray head at a flow rate in excess of 10 CFM at said spray head and at a pressure of no more than 15 psi at said spray head for emission from said atomizing air orifice break up the flat fan-shaped pattern of coating material into a flat fan-shaped atomized spray and from said opposed side port air orifices to impinge jets of air against opposite sides of the spray;
• means for adjusting the volume flow rate of air emitted from said side port air orifices;
• and means, responsive to operation of said adjusting means, for concurrently adjustably controlling the volume flow rate of air supplied to said spray head to prevent the pressure of air at said spray head from exceeding a selected maximum pressure as a result of changes in the volume flow rate of air emitted from said side port air orifices.