5 Things You Need to Know When Shopping for Check ...

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Authors: Mike Lassas &#; President/CEO and Cal Hayes  &#; General Manager, WaterWorks Division

Check valves are typically installed into the discharge piping of a pumping system to ensure that the material being pumped does not flow backward. With so many check valves available to the market, it can be a challenge to find the right one for your application. Before you start shopping for check valves, make sure you know the answers to these five questions.

1. What service will the valve be operating in? i.e What is the application? It is critical to know what you want your valve to do so that you can select the correct valve for your specific application. It is quite common to have the wrong check valve installed in a piping system, which typically happens when check valves are selected based on the size of the pipe instead of the flow conditions.  
2. What is the flow rate? It is very important to know the rate of flow in terms of gallons per minute (GPM), gallons per hour (GPH), or liters per second (L/S). If your application has a flow rate of higher than 8 feet per second flowing through the valve, you will experience a higher rate of wear and tear. When flow is higher than 8 feet per second, abrasion will cause deterioration to any valve, regardless of whether it is a rubber-seated valve or a metal-seated valve. The faster the flow, the more wear you will see on your check valve, resulting in decreased life. Knowing your flow rate can help you pick a check valve best suited for your specific application. 
3. What is the inlet pressure?  Knowing the inlet pressure will help determine which style of check valve you might need. Do you need a &#;Slip On&#; style check valve? Do you need a &#;flanged&#; style check valve? Or do you need an &#;inline&#; style check valve? A slip on style check valve typically is installed at the end of a discharge pipe. An inline style check valve is typically installed in the middle of a piping system. You can also have a flanged in-line check valve or a flanged end-of-line check valve. Deciding which to use really depends on where the check valve will be located in your pumping system. 
4. What is the back pressure?  Back pressure is the differential pressure between the inlet and outlet pressures. For example, imagine a valve is installed at the end of a pipe which is draining fluid into a creek. When that creek rises, how high will the water rise about that valve? When the water rises above that valve, back pressure is created. So with your specific application, you should know how much back pressure the check valve will need to withstand. 
5. Will the valve be installed  in a submerged condition?  If the valve is installed in a submerged condition, this means that there will always be back pressure on the valve. If that is the case, you want to chose a check valve designed a submerged conditions and manufacture from the correct materials to accommodate the constant back pressures that result from submerged conditions. 

It is extremely common to have the wrong check valve put into a piping system. If you are having frequent problems with your check valves, it could be a result of improper selection. Before shopping for a check valve, review your maintenance history, find the answers to the question above, and then consult with the check valve specialists at Proco Products, Inc. Check out the Guides in the Proco Tool Box to learn more.  

*Reproduced from an article featured on www.empoweringvalves.com. To view the article, click here.*

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.

Goto Yaxing Valve to know more.

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.

For more Water Valves And Fittingsinformation, please contact us. We will provide professional answers.