The diagram below shows a cross section through a WAGNER powder injector:
The functional principle
Compressed air from the feed air connection is pushed
through the injector nozzle (also known as the Venturi
nozzle) into the collector nozzle. The small diameter of
the nozzle ensures a high air velocity.
On its way through the injector the feed air passes across the powder
suction tube where it sucks in powder due to the vacuum. The air and the
powder now continue to flow at a high velocity through the collector nozzle
into the powder hose and finally to the spray gun.
Good to know: The powder particles must be delivered at a speed of around 12 m/sec in order to achieve a uniform powder delivery
and a soft cloud.