Control Valves Modulation Vs On-Off

The US economic recovery faces significant risks in 2022. You want your business to be as competitive as possible in this rapidly-changing environment. You can’t afford unnecessary downtime or inefficiencies.

Using the right control valves helps you optimize your flow control system. Is it time for a new on-off or modulation control valve?

Learn more about the difference between an on-off valve and a modulating control valve. You’ll see what these types of valves can do for you.

On-Off vs Modulating Control Valves

On-off and modulating valves give you different levels of control over your fluid control system. Each type of valve has different applications.

On-Off Control Valves

An on-off valve is either open or closed. It allows unrestricted flow or prevents the flow entirely. On-off valves are also called stop, shutoff, or isolation valves.

Uses for on-off valves include:

Routing process fluid to different locations
Starting and stopping processes
Emergency shutoff

An on-off valve can be a backup for a modulating valve.

Modulating Control Valves

A modulating control valve gives you precise control over the flow rate in your system.

The valve actuator allows the right flow rate by using feedback and control signals to open and close the valve. The digital positioning system compares the physical position of the shaft to the desired position. If the valve isn’t in the correct position, the control unit will open or close the valve to reach the right position.

Modulating control valves let you position the valve anywhere between fully open and fully closed, which is typically between 0º and 90º. Regulating the flow rate lets you control other system variables like temperature, liquid level, or concentration.

Modulating valves are ideal for applications that need a high level of precision, such as:

Power plants
Wastewater treatment
HVAC systems
Irrigation systems

A modulating valve can be more energy-efficient than a frequent on-off action.

Automated Control Valves

Automating the actuator for an on-off or modulating control valve gives you several benefits. Automation can increase safety and give you better output control. Electric, pneumatic, hydraulic, or electro-hydraulic energy can power a valve’s control system.

Electric Actuators

An electric actuator converts electrical energy into torque to open or close the valve. They operate using either a motor or a solenoid.

Electric actuators give you extremely precise control. They have a shorter cycle time than pneumatic actuators, and they’re more energy efficient.

Pneumatic Actuators

A pneumatic actuator converts air pressure into valve motion. Pressure from an external air or gas source operates a piston in a cylinder that opens or closes the valve.

Pneumatic actuators require very little maintenance because of their simple design. They’re safe and reliable. They’re a good choice for many types of hazardous locations.

Hydraulic Actuators

A hydraulic actuator works using pressurized liquid. Most hydraulic actuators use a piston to convert fluid pressure into mechanical force. The valve stem transmits the motion of the piston to open or close the valve.

Hydraulic actuators can create a large amount of force. They have very stable positioning. They’re durable and give you a high level of precision.

Electro-Hydraulic Actuators

An electro-hydraulic actuator combines features of electric and hydraulic actuators. It’s a self-contained actuator that doesn’t need a separate hydraulic system.

Electrical power energizes a motor that runs a hydraulic pump. The pressurized fluid works the mechanism to open and close the valve.

Electro-hydraulic actuators are fast, very precise, and cleaner than standard hydraulic actuators.

Types of Valves for On-Off or Modulation Control

Choosing the right type of valve for your application depends on many factors. Some valves are well-suited for on-off service, while others are better for modulating control.

Ball valves and plug valves are two types of valves that work best in on-off applications. Butterfly valves and globe valves are good options when you need a modulating control valve.

Ball Valve

A ball valve is a type of quarter-turn valve. A rotary ball with a bore rotates 90º from off to on.

Ball valves are best-suited for on-off applications. They have a long service life. They provide reliable sealing even after a long period without use.

Specialized ball valves can give you modulation control, but they’re less precise than other types of modulation valves.

Plug Valve

A plug valve is similar to a ball valve. Instead of a ball rotating to open and close the valve, plug valves have a rotating cone. This conical shape helps plug valves seal exceptionally tightly.

Plug valves are a reliable shutoff option for applications involving hard or corrosive mediums, mud, slurries, or sewage.

Butterfly (Disk) Valve

A butterfly valve is another type of quarter-turn valve. It has a disk that rotates 90º to open and close the valve.

Butterfly valves can serve in on-off or modulating applications. A butterfly valve is fully closed with the disk perpendicular to the flow direction. Partial rotation allows for a throttled or proportional flow.

Butterfly valves are available in very large sizes. They can handle slurries and liquids with a high percentage of solids. These features make high-performance butterfly valves increasingly popular.

Globe Valve

Globe valves are linear movement valves. They have sphere-shaped bodies divided into two chambers with a hole that lets fluid pass between them. The up or down motion of the stem raises and lowers a small plug to open and close the valve.

Globe valves can give you modulation control and on-off service. They’re available in three body designs with different advantages. For example, an angle pattern design can handle applications with a pulsating flow.

Finding the Right On-Off and Modulation Control Valves

On-off and modulating control valves serve equally important but different functions in your fluid control system. Finding the right valve for your application is critical for the safety and efficiency of your operations.

Anything Flows specializes in flow control solutions. We’ll help you find the right control valves to meet your requirements. You can count on our expedited logistics to deliver what you need when you need it.