You might also see valves classified by function instead of design.

Common functional designations and their common design types include:

• Isolation Valves: Ball, butterfly, diaphragm, gate, pinch, piston, and plug valves
• Regulation Valves: Ball, butterfly, diaphragm, globe, needle, pinch, and plug valves
• Safety Relief Valves: Pressure release and vacuum relief valves
• Non-Return Valves: Swing check and lift check valves
• Special Purpose Valves: Multi-port, float, foot, knife gate, and line blind valves

Valve Sizing Explained: Keeping Things Flowing

While valves might be a small part of your piping process or system in terms of space, they’re often a substantial portion of the design and build budget. They also have a significant impact on long-term costs and overall system performance.

Choosing a proper valve size is essential to both optimizing costs and ensuring safe, accurate, and reliable operation.

The first thing to consider is the overall size of the valve -- both in terms of physical dimensions and in terms of internal size and flow rates (CV).

Choosing a valve that does not fit properly in the space required could result in added costs. Choosing a valve which does not provide the ideal flow rate can lead to inaccurate flow control at the least and complete system failure at worst.

For example, if your valve is too small, it could cause reduced flow downstream while creating back-pressure upstream. If the valve is too large, you’ll find that flow control is drastically reduced the further you move from fully open or fully closed.

When choosing the proper size, be sure to consider both the connector diameter and the overall flow rate of the valve compared to your needs. Some valves offer excellent flow while others constrict flow and increase pressure.

This means sometimes you must install a larger valve to adjust for flow than the adapter diameter alone might imply.

Valve End Connections: The Key to a Good Fit and Proper Operation

With sizing and design out of the way, it’s also important to consider valve end connections.

While the most obvious implication here is choosing an end connection compatible with your piping, there are also functional characteristics to common end types that might make one valve more suited to your needs than another.

Common valve connections and ends include:

• Screwed or Threaded: Often used in instrument connections or sample points
• Flanged: The most common ends for piping use
• Butt Welded: Typically used in high-pressure or high-temperature operations
• Socket Welded: Commonly used on small bore piping where threaded connections are not permitted
• Wafer and Lug: Often used for compact valves installed in systems with limited space

Valve Materials: Ensuring Safety and Long-Lasting Performance

Depending on your intended use, the materials with which your valves are made might be a critical aspect in ensuring safe operation and reducing maintenance and replacement costs over the life of your operation.

Stainless steel valves are excellent options in a range of processing environments, including those involving corrosive media (such as chemicals, saltwater, and acids), environments with strict sanitation standards (such as food and beverage manufacturing and pharmaceuticals), and processes involving high pressure or high temperatures.

However, if you are processing solvents, fuels, or volatile organic compounds (VOCs), choosing a valve material from a non-sparking material -- such as brass, bronze, copper, or even plastic -- is often a better option. In addition to selecting the correct body material, internal (wetted) trim parts should be evaluated for chemical compatibility as well. If your valve contains elastomers, they should also be evaluated for their chemical compatibility as well as pressure and temperature limitations.

Valve Standards: Meeting Compliance and Regulatory Concerns

Depending on your intended usage, you might find that valves must adhere to particular standards to meet regulatory requirements for safety, sanitation, or other concerns.

While there are too many standard organizations and potential regulations to cover in detail, common general standard organizations include:

There are also industry-specific standards to consider.

Major standards organizations by industry include:

• ASHRAE Valve Standards
• ASME BPVC Valve Standards
• ASSE Valve Standards
• ISA Valve Standards
• NFPA Valve Standards
• SAE Valve Standards

Final Thoughts

Choosing the right valve for your project might seem complex. However, by starting with general characteristics -- such as valve design, valve size and actuation method -- you can quickly limit your options to determine the best valves for your needs.

Whether you’re designing a new processing system or looking to make upgrades to or maintain an existing system, Unified Alloys’ selection of valves and fittings can help you find the ideal solution for your application and usage environment. As a leading provider of stainless steel alloys, valves, flanges, and more, our experts have helped industries across Canada and North America for more than 4 decades. Need assistance or have a question? Contact us for personalized help.

A Beginner’s Guide to Different Valve Types

A Beginner’s Guide to Different Valve Types

There are now 6 official branches of engineering and hundreds of subcategories beneath them. The engineering knowledge out there is wide and varied, but a basic understanding of the main types of valves is valuable in almost any field of the profession.

For those who are unfamiliar with the different valve types, or who simply need a little refresher, here’s a simple breakdown.

Valve Types in a Nutshell

In the most simple of terms, valves control the flow of fluids. Valve types can be broken into two basic categories: control valves, and shut-off valves.

Types of Control Valves

In a control loop, these valves act as the correcting element. There are hand-operated control valves, but typically they work automatically. Examples include ball and plug valves, needle valves, butterfly valves, and check valves to name a few.

1. Needle Valve

When you have tiny piping with a small diameter, needle valves provide accurate control of the fluid flow.

2. Pinch Valve

Sometimes known as the clamp valve, the pinch valve uses a rubber tube and clamp to help control fluid flow. Pinch valves work best at controlling fluids with suspended solids.

3. Ball Valve

Ball valves are fast-acting. A ball-shaped disk controls the fluid flow with when the fluid valve is turned 90 degrees. 

With a quarter-turn, the rotary motion valve opens and closes as the ball-shaped disk allows fluid to flow through. 

4. Check Valve

In pipes, check valves stop backflow. Fluid pressure opens the valve. The genius of the check valve is that it closes if any fluid reverses the wrong direction.

5. Plug Valve

As the name indicates, a plug valve stops the flow of fluids through a pipe by blocking them with a cylindrical plug. Like the ball valve, this occurs through rotary motion.

Plug valves are offer ultra-tight shut-off in high-pressure, vacuum and high-temperature situations.

6. Butterfly Valve

Butterfly valves are a bit more complex as they can start, stop, and control flow. They are light and small, making them useful in big valve applications as they don’t take up as much space.

Types of Shut-off Valves

Also known as “gate valves,” shut-off valves don’t control flow. Like control valves, they can be operated by hand or automatically. Shut-off valves have only two options, on or off. 

They either allow full flow of a fluid or none at all.

1. Pressure Relief Valve

Pressure relief valves release the vacuum/pressure to protect other equipment in case too much pressure builds up.

2. Globe Valve

Globe valves work well at shutting off fluid flow where leak tightness is essential. Slightly more expensive than gate valves, they are more effective at shut-off.

3. Gate Valve

In processing plants, gate valves are the most common. Gate valves are linear and provide effective shut-off. They remain either totally open or closed.

How to Choose the Right Valve

Having a basic understanding of valve types will help you select the valve the best suits your needs. 

Of course, having professional assistance in determining what valves will be most effective for your pipping is always wise. Contact our experienced team of professionals today for a consultation.