The factors of nozzle selection include flow rate, pressure, spray angle, coverage, impact force, temperature, material and application. These factors often involve each other and restrict each other. Flow rate and pressure, spray angle and coverage are directly proportional to each other. The purpose of any nozzle is to keep the bath liquid in contact with the workpiece continuously. The flow rate is more important than the pressure. The temperature of the liquid does not affect the spray performance of the nozzle, but it affects the viscosity and specific gravity, and also affects the material selection.
The nozzle with a certain impact force should choose a small angle nozzle, with the liquid column flow as the best; the fan nozzle is suitable for cleaning, degreasing, cooling and other aspects. Take the "V" fan nozzle as an example, its spray angle is 50 degrees, which has a large impact force; while for the phosphating process, the centrifugal nozzle with good atomization, fine and uniform water particles and weak impact force can be selected ”The optimum distance between the nozzle and the workpiece is 40cm ~ 50cm, which has the function of dispersing and atomizing liquid. Two forms of parallel and cross can be adopted. For the channel type, the vertical cross arrangement is adopted, and the spraying effect is better. Conical nozzle is suitable for bleaching, surface coating, phosphating, humidification, dust removal, etc.; Venturi mixing nozzle should be installed in paint storage tank and tank body. Take "g" type mixing nozzle as an example, the tank liquid is mixed with the liquid inhaled at the approach port at a flow rate of 1:4.5 and then diffused and ejected to achieve the effect of mixing solute without air, thus preventing precipitation For agitation, the chemical solution is evenly mixed.
The material of the nozzle should also be determined according to the chemical characteristics of the bath solution. For non corrosive bath liquid, bronze casting or plastic die casting can be used according to the difficulty of processing. In order to prevent corrosion, non-metallic materials can be used; for sulfuric acid, hydrochloric acid and other strong corrosion bath liquid, nylon plastic can be used; the nozzle material for phosphating bath liquid is generally acid resistant stainless steel, and the nozzle to prevent corrosion can also be directly made of stainless steel or nylon.
