Industrial Control Valve: What it is, Types, and Selection Criteria

By Cematic  |  Instrumentation and Process Control  |  8 min read

In every industrial process, there is at least one variable that must be kept under control: the flow of a liquid, the pressure in a pipe, the level in a tank, or the temperature of a reactor. The control valve is the final control element that makes this regulation possible — it receives the signal from the control system and physically adjusts the fluid passage to maintain the variable within the desired setpoint.

Selecting the correct control valve can seem complex given the number of types, materials, sizes, and accessories available. This technical guide explains everything you need to know to make the right decision — from the basics to industry-specific selection criteria.

What is a control valve and how does it work?

A control valve is a motorized valve — with a pneumatic or electric actuator — designed to modulate the fluid passage in response to an external command signal. Unlike an on-off valve that only opens or closes, a control valve can be positioned at any point between 0% and 100% open, allowing continuous and precise regulation.

The typical control system with a valve operates in a closed loop: a sensor measures the process variable (flow, pressure, level, or temperature), the PID controller calculates the necessary correction and sends a signal — typically 4 to 20 mA — to the valve actuator, which adjusts the opening to correct the deviation from the setpoint.

Elements that make up a complete control valve:

·       Valve body: globe, segmented ball, butterfly, or diaphragm depending on the application

·       Actuator: pneumatic (single or double acting) or linear/rotary electric

·       Digital positioner: receives the 4–20 mA signal and precisely positions the actuator

·       Local position indicator: displays the opening percentage in the field

·       Accessories: emergency shut-off solenoids, air regulators, pressure gauges

Types of control valves and when to use each

Globe Valve — The standard for flow control

This is the most widely used type in process control. Its plug moves linearly over the seat, offering excellent throttling and predictable flow characteristics. Available in straight-through, angle, and three-way configurations for mixing or diverting. Ideal for controlling the flow of water, steam, oils, and clean fluids with moderate flow rates.

·       Advantage: high rangeability (up to 50:1) and linear or equal percentage flow characteristic

·       Typical application: temperature control in heat exchangers, flow regulation in process lines

Segmented Ball Valve — For fluids with solids or viscous fluids

The V-port ball offers a shearing action on the fluid, making it ideal for fluids with suspended particles, slurries, fibers, or viscous fluids that would clog a globe valve. It has excellent self-cleaning capabilities and a high Cv for its size.

·       Advantage: clog-resistant, high Cv, low operating torque

·       Typical application: pulps, sludges, thick food products, paper industry

High-Performance Butterfly Valve — For large diameters

High-performance butterfly valves (double or triple eccentric disc) offer good control in large diameters where a globe valve would be too expensive or heavy. They are not ideal for precise control in small opening ranges but are very efficient in diameters from DN 100 to DN 600.

·       Advantage: economical in large diameters, lightweight, easy maintenance

·       Typical application: flow control in potable water, treatment plants, industrial HVAC

Linear Electric Control Valve — Without compressed air

When compressed air is not available on site or very precise position control is required, the control valve with a linear electric actuator is the solution. The electric motor directly drives the stem, with position controlled by an encoder and integrated feedback signal.

·       Advantage: no compressed air required, exact position with encoder, remote installation

·       Typical application: smart buildings, HVAC, advanced irrigation systems, remote processes

Comparison of control valve types

Selection criteria: how to choose the right control valve

Choosing the wrong control valve is one of the most costly mistakes in process engineering. An oversized valve operates in the first few percent of opening with poor rangeability and cavitation. An undersized valve cannot deliver the required flow. Key criteria are:

1.     1.  Required Cv — Calculate the necessary flow coefficient using the standard ISA formula: Cv = Q √(ΔP/G). The nominal Cv of the valve should be between 20% and 80% of its maximum Cv under normal operating conditions.

2.     2.  Process fluid — Type (liquid, gas, steam), vapor pressure, viscosity, presence of solids, corrosivity, minimum and maximum temperature.

3.     3.  Differential pressure — The available pressure drop across the valve determines the size and the risk of cavitation or flashing in liquids.

4.     4.  Flow characteristic — Linear (for constant ΔP) or equal percentage (for variable ΔP, the most common case in process).

5.     5.  Body material and sealing — WCB steel for general fluids, 316L stainless for corrosive fluids, Hastelloy for concentrated acids. PTFE, VITON or NBR seals depending on temperature and chemical compatibility.

6.     6.  Automation level — 4–20 mA signal with digital positioner for continuous modulating control from PLC/DCS, or On/Off with solenoid for simple shut-off.

Applications by industry

Oil & Gas and Petrochemical

Control valves in Oil & Gas handle some of the most aggressive fluids: H₂S crude, high-pressure gas, corrosive condensates, and multiphase mixtures. API-certified carbon steel bodies with cavitation-resistant trim and NACE MR0175 compatible materials for sour service are required. The digital positioner with HART communication allows integration into the plant DCS for flow control in separators, compression trains, and process units.

Food and Beverage Industry

Flow control in pasteurizers, ingredient dosing, and CIP lines requires valves with 316L stainless steel bodies, polished internal surfaces Ra ≤ 0.8 µm, no dead zones, and sanitary clamp sealing. Control valves must be removable for cleaning and inspection, and compatible with acidic cleaning fluids without seal degradation.

Water Treatment

Pressure and flow control in distribution networks, reverse osmosis, and water treatment plants typically use globe or high-performance butterfly valves in ductile iron or epoxy-coated steel. The 4–20 mA signal from the positioner allows control from municipal SCADA for optimization of the hydraulic network.

Frequently asked questions about control valves

❓  What is the difference between a control valve and a pressure regulating valve?

A control valve receives an external signal (4–20 mA) and adjusts its opening commanded by the control system. A pressure regulating valve (PRV) acts autonomously: it detects the downstream pressure and maintains it at a mechanically fixed setpoint without the need for an external signal or control system.

❓  Can I use a standard ball valve as a control valve?

A standard ball valve with an actuator and positioner can function as a control valve in low-demand applications. However, for precise control, a V-port segmented ball valve or a globe valve is recommended, as they offer better flow characteristics and higher rangeability than a full-port ball valve.

❓  What does Cv mean in a control valve?

Cv is the flow coefficient that indicates how many gallons per minute of water at 60°F the valve can pass with a pressure drop of 1 PSI at full opening. It is the main sizing parameter: a valve with Cv = 10 passes 10 GPM with ΔP = 1 PSI. The required Cv is calculated based on actual process conditions.

❓  What do fail-open and fail-close mean in a control valve?

It defines the safety position of the valve when the air supply or control signal fails. Fail-open (FO): the valve opens by spring upon failure — used when the process needs flow to be safe (reactor cooling). Fail-close (FC): the valve closes upon failure — used to isolate hazardous fluids or prevent spills.

❓  How long does it take to supply a complete control valve?

Standard control valves in 316L stainless steel with pneumatic actuator and digital positioner have a lead time of 5 to 10 business days from Cematic. For special valves (exotic materials, ANSI 300 pressure classes or higher), the estimated time is provided at the time of quoting.

Cematic control valves: complete solution assembled and tested

At Cematic, we supply complete control valves — body, pneumatic or electric actuator, and digital positioner — assembled, tested, and with a commissioning datasheet. We cover applications in water, steam, gases, oil, corrosive fluids, and sanitary fluids, with quotation times of less than 24 hours.

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