Tipos de válvulas
INTRODUCTION
A valve can be defined as a mechanical device with which the circulation (passage) of liquids or gases can be started, stopped or regulated by means of a movable part that opens, closes or partially obstructs one or more orifices or conduits.
Valves are among the most essential control instruments in industry. Due to their design and materials, valves can open and close, connect and disconnect, regulate, modulate, or isolate a vast array of liquids and gases, from the simplest to the most corrosive or toxic. Their sizes range from a fraction of an inch to 30 ft (9 m) or more in diameter. They can operate at pressures ranging from vacuum to over 20,000 psi (140 MPa) and temperatures from cryogenic to 1500 °F (815 °C). In some installations, absolute sealing is required; in others, leaks or seepage are not a concern.
The word flow describes the movement of a fluid, but it also means the total amount of fluid that has passed through a given section of a conduit. Flow rate is the flow per unit of time; that is, the amount of fluid that flows through a given section of the conduit in a unit of time.
Valve categories.
Due to the various factors involved, a universal valve is not possible; therefore, to meet the evolving needs of industry, countless designs and variations have been created over the years as new materials have been developed. All valve types fall into nine categories: gate valves, globe valves, ball valves, butterfly valves, pinch valves, diaphragm valves, plug valves, check valves, and relief valves.
These basic categories are described below. It would be impossible to list all the features of every type of valve manufactured, and no attempt has been made to do so. Rather, a general description of each type is presented in a general format, along with recommendations for service, applications, advantages, disadvantages, and other useful information for the reader.
Literature
Industrial Maintenance Manual by Robert C. Rosaler, James O. Rice. Volume III. McGraw-Hill Publishing.
Instrumentation for measurement and control, by WG Holzbock.
CEC Publications
This article is a reproduction of the work «Valves: Instrumentation and Control» by Enrique Jose Caroli, published at http://www.monografias.com/trabajos11/valvus/valvus.shtml