Follett PB501741

COUPLING VALVE

A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.

Alternatively, in plumbing or with tubing a coupling connects two pipes. If their sizes differ, the fitting is known as a reducing coupling, reducer, or an adapter. There are two types of couplings: "regular" and "slip". A regular coupling has a small ridge or stop internally, to prevent over-insertion of a pipe, and thus under-insertion of the other pipe segment (which would result in an unreliable connection). A slip coupling (sometimes also called a repair coupling) is deliberately made without this internal stop, to allow it to be slipped into place in tight locations, such as the repair of a pipe that has a small leak due to corrosion or freeze bursting, or which had to be cut temporarily for some reason.