Control Valves Key Terms

Get acquainted with terminology related to control valves

By Howard Robertson

A control valve is required for controlling system parameters such as flow, pressure, temperature and fluid level. You must select the most suitable control valve for your application, as control valves come in various categories according to their operation and construction.

Whether you want to install or repair a control valve, you will need to understand the technical language while interacting with vendors and service providers. This guide will familiarize you with some important terms that indicate the types, properties and measurement units of control valves.

Globe valves

A globe valve is a linear motion valve that is useful for metering or regulating the fluid flow. For applications with high operating pressures, globe valves can be used.
Try: For detailed information about the construction, application and specification of a globe valve, read through the globe valve description at GlobalSpec.

Ball valves

A ball valve is a valve with a spherical closure member. These valves are on/off valves useful for applications where reliability of the valve is critical.
Try: To learn more about ball valves, read through the glossary of technical terms at Crane Supply (PDF), a distributor of valves, fittings and piping accessories.

Butterfly valves

A butterfly valve has a circular disc or vane with its pivot axes at right angles to the direction of the fluid flow. When rotated on a shaft, the circular disc seals against the seat in the valve body and restricts the fluid flow.
Try: Valve World, a magazine for the valve industry, provides a glossary that explains various technical terms, such as ball valve and butterfly valve.

Actuator

An actuator is an important component in a valve assembly as it controls the movement of the closure member of the valve.
Try: For descriptions of actuators and actuator assembly, read through the process control valve terminology at Emerson Electric Co. (PDF).

NC or NC position

The position of a control valve is specified as normally closed (NC) or normally open (NO). As the name indicates, a normally closed valve is closed in routine application and is opened as required. For a normally open valve, the case is the opposite.
Try: Plast-O-Matic Valves, a supplier of industrial valves, offers a glossary that explains valve terms and abbreviations, including NC and NO.

Flow characteristics

The flow characteristics of a control valve define the relationship between the valve opening and the fluid flow rate at constant operating pressure.
Try: You can browse through the control valve tutorial at Spirax-Sarco, an expert in steam system solutions.