Adjust the pressure of the spray gun in strict accordance with the construction parameters provided in the oil and gas product manual. For any paint system, there is only one most appropriate air pressure, which is the lowest air pressure that can make the paint get the best atomization.
Due to friction, when the air flows from the dryer pressure regulating valve to the spray gun, the pressure will decrease. The amount of the loss depends on the length and diameter of the air pipe.
It is best to connect a pressure regulating valve (with a pressure gauge on the valve) between the hose connector and the spray gun to check and adjust the spray gun pressure. The optimal pressure refers to the lowest pressure required to obtain proper atomization, volatilization rate and spray fan width. If the pressure is too high, a large amount of paint will be wasted due to flying paint, and the solvent will evaporate quickly before reaching the surface of the component, resulting in poor fluidity and easy to produce defects such as orange peel. If the pressure is too low, the solvent retains too much, resulting in poor drying performance, and the paint film is prone to foaming and sagging. Different quality spray gun have their own best valve for the air pressure.
Screw the knob of the mist control valve in to get the smallest round mist beam, and screw the knob out to get the largest mist shape.
Adjusting the air cap can change the direction of the mist. Adjust the angle of the air cap to be parallel to the ground, and the sprayed mist beam is flat and perpendicular to the ground, which is called vertical mist beam. This method is widely used- if the angle of the air cap is perpendicular to the ground, the sprayed mist beam is plane and parallel to the ground, these are called horizontal fog beams. This method is rare in construction and is generally used for vertical sweeping in large-area construction.
The paint flow control valve is used to adjust the paint flow according to the selected fog shape. The paint flow increases when the control valve is screwed out, and the paint flow decreases when the control valve is screwed in.
Through the fog test to see the sag condition and check whether the adjustment is correct. Loosen the air cap positioning ring and rotate the air cap so that the horn mouth is in a vertical position. Then pray again and hold down the trigger until the paint starts to flow down, that is, sagging. Check the sags condition. If the adjustments are correct, the length of the sags should be approximately equal. If the sagging is in a divided shape, it is because the spray beam is too wide or the air pressure is too low. Screw the mist control valve into a half turn, or increase the air pressure a bit, and perform these two adjustments alternately until the sag lengths are uniform. If the lengths of the sags are short on both sides, it is because too much paint is sprayed and the paint flow control valve should screw up until the lengths of the sags are uniform.