Top 10 questions you should ask when purchasing a control valve

Jul. 21, 2025

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Top 10 questions you should ask when purchasing a control valve

Automatic control valves, much like everything else we purchase these days, are not all created equal. Some fall into the high quality bracket with pricing to match, while others hover closer to the lower quality and price sensitive end of the scale. Unfortunately, when evaluating control valve prices, it is not always clear what you are being offered and what standards the valve actually meets. Here are a few questions to consider and ask the supplier to ensure you get years of trouble free operation that lasts longer than it takes the sales person to drive out of your parking lot!

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Q 1 What materials are being used?

Make sure you know what the different components of the valve are made of, as this will certainly affect the life of your valve, specifically:

Body Material – is the valve body cast iron or ductile iron? Traditionally valves were cast iron but ductile iron has become the new standard due to its superior physical properties that are much better at weathering the elements.

Body Coating – Most of the world insists on fusion bonded coating of a valve, inside and out. Unfortunately here in North America, that is not always requested. This just makes common sense for valves that are constantly wet and sit in locations that are not always dry and pristine. A valve should last for many years, so insisting on a coated valve is a wise choice.

Seat Material – bronze is typically the common material for seats but over time, depending on water quality and velocities, bronze wears resulting in the need for replacement. This is time consuming and expensive as seat replacement requires a complete disassembly of the entire valve. Ideally go for stainless steel.

Valve Internals – Most valve manufacturers utilize stainless steel for their valve stems. Make sure that you ask what grade of stainless you are getting as not all stainless steel is created equal. 316 SS is always the best choice because it is harder and least likely to corrode.

External Fasteners – Over time valves experience condensation or flooding and this can play havoc with coated studs or bolts. There is nothing worse than trying to remove heavily rusted studs out of an old valve to perform maintenance. Request stainless steel fasteners as this will ensure that bolts will be removable at any age.

Q 2 Does the valve supplier fully understand your application?

Too frequently a specification will be requested and a valve is supplied that is simply the wrong valve for the job. It may also be the case that there is just a better solution. Ensure you give your valve supplier all the necessary pressure and flow details including details of the actual application and what you want this valve to do. Having the wrong valve for the wrong application, at best case will result in a significantly shorter life and worst case, a malfunction that can result in destruction of the valve and other parts of your water distribution system.

Q 3 Will this new valve fit into my existing piping layout?

Don’t be tempted to just stay with brand X because that is the valve you may be replacing and has the same lay lengths. Most manufactures can be quite innovative on providing solutions to combat varying lay lengths so explore all of you options rather than just settling because you think it may be easier.

Q 4 Do you need specialty tools for maintenance?

Nobody wants to have to carry around a specific tool that only performs one task. Ensure that your valve can be maintained with everything you would carry in regular tool kit. Some valve manufacturers require specialized seat removal tools, or vice jaws installed with copper jaws to protect valve stems. While these are great ideas, they are certainly not things that the average operator has in his toolkit.

Q 5 Will your personnel receive complimentary factory qualified training?

Control valves are not so difficult to understand and once taught, most operations personnel can easily perform maintenance. Ensure that you will not be reliant on the additional cost of having to bring out a factory person every time your valve requires maintenance. Request that a factory-trained representative is on site when the valve is commissioned. This will allow your operators to be schooled in the regular maintenance needs, know what to look for if things go awry and how to start up a valve in a new system or after service. Simple tricks like removing air out of the pilot system are valuable lessons to see in practice.

Q 6 Does your valve have a solid warranty?

These days having a product with the long term back up of the factory is important. Three years should be the standard to ensure there are no manufacturing faults.

Q 7 Can I make changes to the valve if required

Having a valve “expansion ready” for the future can save you money and make your decisions a whole lot easier. For example, can you add a limit switch or a position indicator easily? Or, if you need to move the pilot system to the other side of the valve, can you do it, or is it not possible because the valve body does not have the required connections? Things always change and a flexible valve gives you more options to keep your now perfect valve, perfect down the road.

Q 8 Does your valve meet industry standards?

There are third party accreditations that ensure your valve was built to the correct specifications. For example; NSF 61, WRAS, UL/FM, AWWA, ISO et.al. They are important because they ensure that the valve has been built to a given standard so the user can be assured they meet approval for such things as low lead content, bacterial growth tests, functional tests etc.

Q 9 Do you have local and factory support?

Make sure there is someone in the area that is factory trained and available to come out and assist when you have questions or problems. This sounds like a given but it’s best to ensure the local agent will in fact be there for you when you need him. When a valve fails, timing is usually of the essence so you should know whom to call prior to such an event.

Q 10 Is the valve solution offered able to handle future needs?

In the world of “low bid wins”, a supplier may be tempted to squeeze as small a valve as possible into the application in order to reduce price. Make sure that the offered solution will supply your needs for the foreseeable future without the burden and additional cost of having to change a valve in a couple of years.

What Is a Valve: Essential Industrial Uses and Types - SkillCat

Understand what valves are, the types of valves that exist, and their uses within piping. In this guide, learn specifically about ball valves, gate valves, globe valves, butterfly valves, check valves, pressure relief valves, and pressure regulating valves.

Want to learn more about valves? Check these links out:

Installing and Testing Fixtures and Valves
Valves, Pressure requirements and Safety

Follow Along on SkillCat: "Piping" Course!

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What Is A Valve?

A valve is a device used to decrease or stop the flow of a fluid in piping. It is a type of pipe fitting that controls the flow inside a pipeline.

Valves can be operated manually by turning the handle of the valve, or automatically by using a pressure difference and an actuator. An actuator is a device that automatically controls the valve on or off.

Types of Valves

There are two categories of valves for piping: shut off valves and regulatory valves. Within each category, there are many types of valves, each with their own handle and use. The types of valves that we'll cover in this guide are:

Ball valve
Gate valve
Globe valve
Butterfly valve
Check valve
Pressure relief valve
Pressure regulating valve

Shut Off Valves

Shut-off valves that are used primarily to start or stop the flow of fluid in the pipe. A shut-off valve can be operated manually, or automatically using external control such as an actuator. An electric motor is a type of actuator that can be used to rotate the handle of a valve. This way the shut-off valve can be operated automatically.

There are many types of shut off valve:

Ball valve
Gate valve
Globe valve
Butterfly valve

Ball Valves

Ball valves are 2-way, 2-position valves used for shut-off or isolation of a system. 2-way valves mean there are two ports (in and out of pipe) and 2-position valves refer to open or closed.

Ball valves can also be 3-way or 4-way. Such multi-port valves are used in piping that require more than one source of flow. For example, if your home is equipped with two sinks. To stop the water supply from one of the sinks, you may use a 3 way shut-off valves.

A ball valve controls a liquid or gas flow using a rotary ball with a hole in the middle. When we rotate the ball valve, the ball aligns with the valve cylinder. This allows liquid or gas to flow through. A slot is machined on the top of the ball. The stem fits into this slot and is bolted to the handle on the other end. As you turn the handle, it turns the ball to open or close the valve.

Ball valves have a fast shut-off with only a quarter-turn or 90° turn to close the valve. This makes them easier to use for applications where frequent opening and closing is required.

Gate Valves

Gate valves work by inserting a rectangular gate or wedge into the path of a flowing fluid. Similar to a ball valve, the stem is connected to the handle of the gate valve. The other end of the stem is connected to a rectangular wedge.

When the hand-wheel is turned, it rotates the stem. This makes the threads on the stem unscrew. Due to movement of the threaded rod, the rectangular wedge attached at the other end of the stem also moves up. This opens the valve and fluid flows through the pipe.

Gate valves are similar to old water taps. They are considered multi-turn valves, as it takes more than one 360° turn to fully open or close the valve. Due to this reason, they are used in applications that does not require frequent opening and closing. Gate valves are easier to clean and maintain though, making them suitable for applications that involve slurries.

Globe Valves

A globe valve is used to stop, start and regulate flow. Unlike a gate valve, a globe valve can control the flow of fluid. A 2-way globe valves are used for single inlet flow and outlet flow. When more than one inlet and single outlet, a 3 way or 4 way globe valves is used.

In globe valves, a disc is used to block the flow through the pipe. The other parts used such as stem, bonnet are similar to gate valves. The disc within the globe valve is designed to move up and down from the seat. These vertical movements allow the space between the disc and the seat to change slowly, giving the valve good control over flow of fluid through the pipeline. The further apart the disc and seat, the more liquid that will flow through the valve. This control of fluid flow is not possible in a gate valve.

The workings of a globe valve is similar to tap used in wash basin and kitchen; as you rotate the tap handle, fluid flow starts gradually and will reach maximum when fully opened. In a globe valve, when the disc is fully lowered, the fluid flow is shut off. When the disc is fully raised, the fluid flows at its maximum rate.

Globe valves are used for regulating and shut off applications in swimming pool drains and lubrication systems. All these systems require starting, stopping and regulating flow for its application.

Butterfly Valves

Butterfly valves are shut-off valves that are used to start and stop liquid flow. They are made to be specifically compact for tight spaces.

In butterfly valves, a disc is used similarly to a globe valve. When the disc within a butterfly valve is completely sideways, fluid is permitted to flow; when the disc of a butterfly valve is upright, the flow of fluid is blocked completely.

Butterfly valves are a quarter turn rotational motion valve, making them great for quick-acting situations. Similarly to ball valves, butterfly valves are easier to use for applications where frequent opening and closing is required.

Regulating Valves

While shut-off valves are used to start and stop the flow inside the pipe, regulating valves are a type of valve used to control the flow. Regulating valves can be considered control valves. Control valves also control fluid flow, hence their name.

Regulating valves are operated and controlled automatically using pressure difference. An actuator is used to actuate valves in order to turn them one way or another. There are many types of actuators, such as hydraulic actuators, pneumatic actuators, mechanical actuators, and more. Actuation is the process of actuating a valve.

There are many types of valves that are regulating valves:

Check valve
Pressure relief valve
Pressure regulating valve

Check Valve

A check valve opens with forward flow and closes against reverse flow to act as a safety device for fluid to flow in only one direction. Check valves are generally installed to prevent backflow. Backflow is when water flows backward in the supply line due to pressure changes.

Check valves require a minimum pressure difference between inlet and outlet to open the valve and allow fluid flow through it. If there is minimum pressure difference or inlet pressure becomes equal to outlet pressure, then the check valve opens. If the inlet pressure starts to fall due to damage to parts, then the check valve will close automatically. Depending on the check valve design, the closing mechanism can change.

Pressure Relief Valve

Pressure relief valves are spring-loaded safety valves. Pressure relief valves are normally closed but are opened automatically when the safe pressure limit is crossed. The safe pressure limit is the pressure at which the valve should be operated.

We release the pressure to protect the system from high pressure damage. That is why the outlet of the pressure relief valve is connected to the tank. This ensures pressure does not build up in the system.

Similar to the spring in a pressure cooker whistle, there is a spring inside the pressure relief valve. This spring is present in the middle of the valve, also called the bonnet. The spring helps to actuate the valve depending upon the pressure.

The safe pressure limit of the pressure relief valve can be changed by adjusting spring tension. An adjustment screw is used to set the pressure of the relief valve. As you loosen or tighten the screw, the tension in the spring is adjusted. This will increase or decrease the set pressure.

In pipes, if the fluid reaches pressure higher than set limit, then the fluid pushes the disc upwards. This pushes the spring attached to the disc. The spring gets compressed and disc is moved upwards to open the valve.

If the fluid pressure from inlet is reduced below set limit, the spring tries to come to its original position. This is because spring force becomes greater than fluid pressure. This causes the disc to come down and close the valve.

Pressure Regulating Valve

Pressure regulating valves are also known as pressure reducing valve. It is normally an open type valve that maintains a constant pressure in the pipeline even when there are fluctuations in the inlet and outlet pressure.

Pressure regulating valves consist of the following elements:

Poppet valve
Spring
Sensing element such as a diaphragm or a piston

As the outlet pressure increases, approaching the set pressure of poppet valve, the fluid is diverted over the diaphragm. The fluid pressure under the diaphragm begins to overcome spring pressure. This forces the poppet valve upward and closes the valve.

When the outlet pressure drops below the set point of the valve, the spring pressure overcomes the outlet pressure. This forces the valve downward, opening the valve.

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As pressure in the inlet side becomes more than set pressure, the fluid enters on the top of the poppet and closes the valve. The valve remains closed until inlet pressure becomes equal to outlet pressure.

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FAQs

What is a valve?

A valve is a device used to control the flow of a fluid in a pipeline. It can either stop, regulate, or start the flow of liquid or gas, depending on the type and application. Valves can be operated manually or automatically using actuators.

What is the function of a shut-off valve?

Shut-off valves start or stop the flow of fluid in a pipe. These valves can be operated manually or automatically through an actuator. Common shut-off valves include the ball valve, gate valve, globe valve, and butterfly valve.

What is a gate valve used for?

A gate valve insert a rectangular wedge into the path of a flowing fluid. It is a multi-turn valve, meaning it requires several turns to open or close fully. These valves are used where frequent opening and closing are not required.

What is the difference between a globe valve and a gate valve?

A globe valve can regulate the flow of fluid, unlike a gate valve that is only used stop or start the flow. The globe valve uses a disc that moves vertically to control the space between the disc and seat, allowing gradual control of the fluid flow.

How does a butterfly valve function?

A butterfly valve is a quarter-turn valve used to shut off or start fluid flow. It uses a disc that rotates 90° to block or allow fluid flow through the pipes. Butterfly valves are ideal for quick-acting applications due to their simple design.

What is a check valve?

A check valve allows fluid to flow in one direction and prevents backflow. It opens when the fluid flows in the correct direction and automatically closes if the flow reverses, acting as a safety feature in pipelines.

What is a control valve?

A control valve is a type of valve used to regulate the flow of fluid (liquid, gas, or slurry) in a system. Control valves automatically adjusts the flow rate, pressure, or temperature based on input signals from a control system, allowing for precise control over the process. Control valves are commonly used in industrial applications, such as chemical plants, water treatment facilities, and HVAC systems, to ensure optimal performance and safety.

How does a control valve work?

Control valves use a combination of a valve body, actuator, and sensor to regulate fluid flow. The actuator (which can be pneumatic, hydraulic, or electric) adjusts the position of the valve's internal components (such as a disc, ball, or plug) based on signals from a control system. These signals, often from a pressure or temperature sensor, tell the actuator to open or close the valve to maintain the desired flow rate, pressure, or temperature.

What is a plug valve?

A plug valve is a type of valve that controls the flow of fluid by using a cylindrical or tapered plug that can be rotated to open or close the flow path. The plug has one or more holes (ports) that align with the pipe's flow path when the valve is open. Plug valves are typically used for on/off or diversion applications and can handle both liquids and gases.

How does a plug valve work?

A plug valve operates by rotating a cylindrical or tapered plug inside the valve body. The plug has one or more ports that line up with the inlet and outlet ports of the valve when it is turned to the open position, allowing fluid to pass through. When the valve is closed, the ports are rotated away from the flow path, stopping the fluid from passing through. The operation is typically manual, but can also be automated with an actuator.

What is the purpose of a pressure relief valve?

A pressure relief valve is used to prevent excessive pressure buildup in a system. It opens automatically when the pressure exceeds a safe limit, allowing the fluid to escape and protecting the system from damage.

An actuator is a device that automatically operates a valve. It uses an external control like pressure difference, electric motors, or hydraulic systems to open or close the valve without manual intervention. Common types of actuators include pneumatic actuators and hydraulic actuators.

Why would I need to use a ball valve over a globe valve?

A ball valve is ideal for applications where quick shutoff is needed, with only a 90° turn required to close. On the other hand, a globe valve is better suited for regulating flow, as it provides finer control over the flow rate.

Can a valve be operated automatically?

Yes, many valves, especially shut-off valves, can be operated automatically using actuators. These actuators use a pressure difference or other control systems to open or close the valve without human intervention.

What is a flanged valve?

A flanged valve is a type of valve that has flanges on either side, which are used to connect the valve to a pipeline. The flanges are typically bolted together, ensuring a tight seal and preventing leaks. These valves are often used in systems that handle high-pressure or high-temperature fluids.

Quiz

Question #1: What is the primary function of a valve?

To increase the flow of fluid
To decrease or stop the flow of fluid
To monitor the pressure of fluid
To regulate the temperature of fluid

Click for the answer...

Answer: To decrease or stop the flow of fluid

A valve is designed to control the flow of fluid in a pipeline, either stopping or reducing it as needed.

Question #2: Which valve type is commonly used for quick on/off flow control and can operate with a 90° turn?

Gate valve
Plug valve
Ball valve
Globe valve

Click for the answer...

Answer: Ball valve

Ball valves are known for their fast shut-off, requiring only a 90° turn to open or close the flow.

Question #3: Which valve type uses a tapered or cylindrical plug to control the flow of fluid?

Gate valve
Plug valve
Ball valve
Butterfly valve

Click for the answer...

Answer: Plug valve

A plug valve uses a tapered or cylindrical plug to control the flow of fluid through the pipe.

Question #4: Which of the following valves is specifically used for regulating flow and pressure in a pipeline?

Check valve
Gate valve
Pressure relief valve
Butterfly valve

Click for the answer...

Answer: Pressure relief valve

A pressure relief valve automatically opens when the pressure exceeds a safe limit, protecting the system from damage.

Question #5: Which type of valve is designed to prevent backflow in a system?

Pressure relief valve
Check valve
Globe valve
Ball valve

Click for the answer...

Answer: Check valve

A check valve allows fluid to flow in only one direction, preventing backflow that could damage the system.

Other References:

If you want to learn more, please visit our website Valve Parts Components.

Butterfly Valve vs Gate Valve: Key Differences Explained 2025

Different Types of Gate Valves

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