How does a venturi supply work in pneumatic transport?

The venturi feeder consists of an air entraining nozzle, arranged so that the high air velocity through the nozzle creates an area of negative pressure in which the material is entrained. These feeders are limited to short distances and relatively slow material flow rates. There are numerous specialized applications including the transport of bottle caps, brittle and degradable products such as chips and a larger application in the transport of agricultural products.