Category Archive: Check Valves
Design Elements to Consider when Selecting a Check Valve
Check valves perform a crucial function in pumping systems by permitting the forward flow of water when open, and preventing reverse flow when shut. When selecting a valve for your water and wastewater pumping system, you will likely want one that not only executes this task, but also does so efficiently.
Check valves should minimize energy consumption and also protect the system from pressure surges caused by water hammer. They should also suit your particular application. The two common types of check valves to examine are silent or in line check valves and swing check valves.
3 Common Problems in Check Valve Selection
Did you know that, unlike other types of valves, check valves continue to work if a plant loses electricity, air, manpower, or all of the above? They come in a wide variety of sizes, materials, and end connections, and can be used in countless applications.
So why is it that they’re often improperly sized or selected? It’s because check valves are only as good as their application. Oftentimes the problems with a check valve are not related to the valve itself, but application and other factors. So when you’re problem solving or replacing a check valve, keep these three common problems in mind:
Water Hammer
Water hammer is one of the most common check valve problems. Water hammer is a pressure surge that’s caused when a liquid or gas is forced to stop or change direction suddenly, and often occurs when a valve is suddenly closed at the end of a pipeline system. This can result in both noise and vibration, which can in turn lead to damage and additional maintenance or repair costs.
Water hammer can be prevented, however, by using a faster-closing check valve that stops the pressure surges and shock waves that can damage and rupture equipment. Our silent check valves in particular are known for their effectiveness in preventing and in many cases eliminating water hammer.
Reverse Flow
Reverse flow is another common check valve problem and can be extremely costly, especially when it occurs at the discharge of a pump, causing the pump to spin backwards.
Is Your Check Valve Oversized for Your Application?
Check Valve Oversizing: Why Bigger Valves Create Bigger Problems
Oversizing a check valve is one of the most common and costly mistakes made during valve selection. While it might seem safer to choose a larger valve, doing so can actually create a chain reaction of performance and reliability issues.
When a check valve is larger than the application requires, there often isn’t enough differential pressure to keep the disc fully open and stable. Instead of operating smoothly, the disc can begin to flutter, rapidly and repeatedly opening and closing due to flow-induced vibration. This constant movement places unnecessary stress on the valve’s internal components.
Over time, disc flutter causes wear on the disc, hinge, seat, and body. The result is shortened valve life, unexpected maintenance, and higher long-term costs. In more severe cases, oversizing can also contribute to noise, pressure surges, and even damage to downstream equipment.
How Check Valves End Up Oversized
Most oversizing issues come from selecting a check valve based only on nominal pipe size. While pipe diameter matters from a mechanical standpoint, it doesn’t tell the full story of how a check valve actually behaves in service.
Unlike isolation valves, check valves depend on flow velocity and differential pressure to operate properly. When a valve is selected simply to match the pipe size, it may never reach its fully open position under normal operating conditions. That not only compromises performance, but also increases upfront costs as larger valves are more expensive to purchase, install, and maintain.
Size for the Application, Not the Line
A core principle of good check valve selection is simple: size the valve for the application, not the pipe. Proper sizing ensures that flow velocities are high enough to fully open the disc and keep it stable across all expected operating conditions.
Treating a check valve like an on/off valve ignores the fluid dynamics that govern its performance. When sized correctly, a check valve operates smoothly, minimizes chatter and delivers predictable pressure drop.
The real advantage is longer service life and reliable, predictable performance.
Application Factors That Matter
To determine the correct check valve size, several application specifications must be considered, including:
- Normal, minimum, and maximum flow rates
- How the flow behaves-steady, intermittent, or highly fluctuating
- Fluid properties such as density, viscosity, and compressibility
- Startup and shutdown conditions, where low or reversing flows are common
Systems with a wide range of flow conditions, often referred to as high turndown applications, present certain challenges. In these cases, a standard pipe-sized valve may be too large to remain stable at low flows. A smaller or sized check valve is often required to maintain adequate flow velocity and prevent flutter at full operating range.
Why Experience Matters in Valve Selection
An experienced check valve manufacturer or application engineer looks beyond pipe size alone. They evaluate flow conditions, operating scenarios, and valve dynamics-before making a recommendation.
Less experienced suppliers may default to pipe-matching practices, increasing the risk of oversizing and early failure. True subject-matter experts understand how valve geometry, flow behavior, and system demands interact, and they guide customers toward solutions that balance performance, reliability, and total lifecycle cost.
If you have questions about check valve sizing or want help evaluating your application, contact DFT to learn more about our DFT’s Check Valve Sizing Program.
You can also download our Check Valve Sizing eBook or watch our DFT Sizing Webinar to learn more about proper selection practices.
You can also download our eBook on Check Valve Sizing from the link below:
DFT’s ALC and WLC Wafer Check Valves
Water hammer and reverse flow can be ongoing issues for large buildings and industrial piping. In the majority of cases, an unreliable double door or butterfly check valve was utilized and the results are these damaging issues. Double door or butterfly check valves often times incur failure of the door spring or hinge pin; leakage from misaligned doors and seats; reverse flow; and even internal parts flowing down stream.
The harming effects of water hammer include loud noise and rapid vibration to pipe collapse. Reverse flow can damage pumps and motors, a costly proposition to any company.
DFT Inc.’s Pulp and Paper Check Valves: Write On!
If you think of paper manufacturing (and its raw material, wood pulp), you probably think of trees, huge mills, and giant rollers. Water and liquid chemical delivery systems might not be the first things that come to mind. Both, however, comprise important steps in both pulp and paper production. Quick explanation: wood pulp is made up of certain fibers from wood, separated out from the main piece. This separation can be achieved through a number of different methods, one of which is through chemicals specially intended to break down the raw wood, while leaving the key cellulose fiber intact. As you might imagine, these chemicals can be fairly harsh, which is why DFT Inc.’s severe service check valves are the perfect replacement for standard swing check valves on batch digester systems.
