# Rieter

### Basic principle

#### Index

Air is not inherently a very efficient transport medium. Very large quantities must be moved at high speeds in order to keep the tufts that are being transported floating. The current of air itself is a further disadvantage, since the air flows in a turbulent fashion through the ducting, i.e. vortexes are created. Since the tufts are subjected to these vortexes, entangling of tufts can arise in long ducts and finally neps can be formed. A closed duct (generally a pipe) and a source of partial vacuum (a fan) at one end of the duct are needed to move the air. The air speed should be at least 10 m/sec, and 12 - 15 m/sec is better; it should never exceed 20 - 24 m/sec. At a given air speed, the required quantity of air can be calculated as:

$L ({m^3}/s) = A \times v$

where L is the quantity of air; A is the cross section of the duct in m2; v is the air speed in m/s. The duct must terminate in a device that separates the air from the material.