Needle assemblies allow the flow of fluid through a spray gun. When the trigger is pulled, the air valve opens and retracts the needle within the gun. With the needle in the dispensing position, liquid flows to the air cap for atomization. A fluid tip in the air cap helps achieve the desired dispensing performance. A fully functioning needle assembly works with the fluid tip, air cap, and trigger to control the flow of material through the gun.
The needle assembly contains spring-loaded parts that affect how far the needle retracts. Adjustments to the fluid control knob affect how far the trigger pulls the needle. At ideal pressure levels, maximum fluid flow and full atomization occur when the needle is fully displaced. Replacement needle assemblies may solve leakage issues in a variety of spray guns. Replacement kits often include a fluid tip to fully restore the inner parts of the spray dispensing unit.