With internal mixing pneumatic nozzles, the liquid and gas streams are mixed inside the nozzle chamber. Hereby, the compressed air/water mixture expands the spray when exiting the nozzle and thereby produces very fine droplets.
In contrast to the external mix, the spray pattern of the internal mix is much easier to control. In addition, smaller as well as larger quantities of liquid can be atomized.
However, internal mixing nozzles are less suitable for viscous media. In addition, great importance must be attached to the correct choice of air/water mixture. A high pressure differantial is not recommended.