a sealed passage between two pneumatic automation devices that has a single inlet and outlet and permits the transmission of pneumatic signals over a distance. Such channels are usually made of rubber, plastic, or metal tubing and connect pneumatic devices and equipment. In the construction of equipment from individual pneumatic components, channels are also made in the boards on which the pneumatic elements are mounted. This type of assembly makes the equipment compact, reduces the length of the channels, and improves reliability.
The cross section and length of a channel have a major effect on the characteristics of pneumatic automation equipment: a very large cross section and length increases the spurious capacitances and, as a result, the consumption of working air, reduces the speed of response of the system, and increases the cost; a reduction in cross sections creates additional resistance. The maximum length of a pneumatic channel is determined by the permissible signal attenuation and is usually about 300 m with a standard cross section of 4—8 sq mm. A channel long enough to have a substantial effect on the characteristics of the equipment in a pneumatic automation system is considered a pneumatic long line, and for the purpose of calculations it is treated as a system with distributed parameters.
REFERENCESZalmanzon, L. A. Protochnye elementy pnevmaticheskikh priborov kontrolia i upravleniia. Moscow, 1961.
Berends, T. K., T. K. Efremova, and A. A. Tagaevskaia. Elementy i skhemy pnevmoavtomatiki. Moscow, 1968.
T. K. BERENDS