Spray Equipment Setup, Operation, and Maintenance
Spray Equipment Setup, Operation, and Maintenance tests safe, repeatable atomization. The goal is a uniform pattern, correct fluid flow, and clean air passages, not maximum pressure.
Core rules
- Match air cap, fluid tip, and needle to the material and gun. A larger tip moves more fluid; too small a tip forces high pressure and poor atomization.
- Set inlet pressure with the gun triggered and flowing, using the manufacturer's specification. HVLP and compliant guns use lower pressure than conventional guns.
- Test the pattern on a clean surface before spraying the vehicle. A split or heavy center means a clogged or damaged air cap or fluid passage.
- Hold the gun perpendicular, typically 6-8 inches from the surface, with consistent speed and 50 percent overlap. Arcing the wrist causes uneven film.
- Trigger at the start and end of each pass; do not fan the gun.
- Clean the air cap, nozzle, and needle with the recommended solvent; lubricate moving parts; never soak the entire gun unless approved.
Worked example
A gun sprays a pattern with two heavy stripes and a light center. The fluid tip is correct and pressure is at spec. The likely cause is clogged center or side holes in the air cap. Clean the cap with a soft tool and solvent, blow dry, and retest. Reason: atomizing air is uneven, so the pattern cannot be corrected by raising pressure.
Traps
Raising pressure to fix a clog, measuring pressure with the gun static, using a worn needle, and soaking the whole gun. Also watch for a fluid tip tightened with pliers, which damages the seat.