For different types of coatings, there are three main factors to consider when choosing the aperture of the matching coating nozzle, namely, the viscosity of the coating, the volume of spraying work and the flow of coating.
Viscosity of small fluid flow resistance is also small, so the use of nozzle aperture can be smaller, the hydraulic pressure used can also be lower; and viscosity of large paint flow resistance, so in order to get enough flow rate, we must use a large diameter nozzle and higher hydraulic pressure. The general paint nozzle caliber is between 0.5~5.0mm, 0.5~0.7mm caliber is used for colorant, insect glue and other easy low viscosity paint spraying, 1.0~1.8mm caliber is used for nitro paint and other viscous paint spraying.
The larger the required paint spraying volume is, the larger the nozzle caliber is, otherwise it cannot deliver more paint in the specified time. There are two basic methods to control the spray flow: one is to change the aperture of the spray hole, and the other is to change the pressure applied to the paint, changing the aperture of the spray hole is a more convenient method.
For ordinary paint, the liquid at the entrance of the gun generally cannot exceed 0.2mpa, too high hydraulic pressure will produce too high spraying speed, so that the air nozzle can not be good and atomization of it, so should follow the selection of the largest possible caliber and the lowest possible hydraulic pressure to meet the flow rate requirements.