6 Check Valve Failure Symptoms and What to Do About Them

Enter: the check valve (aka the non-return valve). This often tiny unassuming component prevents backflow via a range of mechanisms, but the result is the same. Your equipment is protected, and your operations are more efficient. That is, provided the check valve is working properly. Lucky for you (and your wallet), check valves don’t die quietly. Learn the early (and late) warning signs of check valve failure, how to address them, and ways to prevent them from happening again.

1. Vibrating

Also referred to as “chattering”, this is when your check valve emits slight rattling noises accompanied by (sometimes subtle) vibrations. Basically, if your check valve is “talking back to you”, then you might have a problem.

Causes

It’s attributed to a range of factors, including mechanical issues, like loose internal parts, and flow issues, like too low pressure or sudden pressure drops that fail to fully open the valve. Chattering could also indicate improper installation - many check valves are orientation specific - or use of the incorrect valve for that particular system.

Risk Factors

If you notice chattering, address it promptly. Inefficient check valves can lead to costly energy waste. Loose parts can also cause additional damage to seals, resulting in sticking or leaking. Ultimately, if left unaddressed, then it could cause equipment failure down the line.

Solution

Assess your check valve to find out why it’s chattering. If there are loose parts, then you may be able to repair or replace just those components. If the valve itself is ill-suited to the current use case because it requires a higher PSI to crack (i.e. your flow is too low), then you’ll need to replace the valve entirely with the right match. Finally, it could be that the valve itself is fine, but its behavior is indicative of another issue. For example, equipment failure or underperformance somewhere else in your system could cause abnormally low pressure and will need to be addressed directly.

2. Loud Banging

As opposed to the rattling noise caused by vibration, this loud banging sounds more like a hammer. In fact, it’s often called “water-hammer”. You might have witnessed this phenomenon at home upon quickly shutting off a faucet and hearing a distant bang.

Causes

Essentially, sudden changes in pressure cause the check valve to rapidly close, resulting in a shock wave that makes a large percussive noise. This can happen with different types of check valves, including diaphragm check valves and swing check valves. However, this spike in pressure signified by a bang is more common in hydraulic systems than pneumatic ones.

Risk Factors

Over time, the sudden pressure surges caused by water hammer may damage pipes and fittings. This in turn may cause leaking, which will further damage your machine.

Solutions

For starters, make sure your chosen check valve is well-suited to the task. But while this may be a case of “wrong application” or “wrong installation”, it’s also something that’s just inclined to happen with certain types of valves. Swing check valves, for example, rely on both pressure reversal and gravity to help them close, often resulting in a bang. This is where tools like water hammer arresters can assist. Also consider checking for any air pockets in the valve, replacing your intake connectors, or installing pressure limiting valves.

3. Unusual Pressure Changes

Your check valve is quite simply not doing its job. It’s there to ensure a steady flow of fluid in one direction. If your instruments picked up on unusual pressure changes, then you’re likely looking at reverse flow (wrong direction) or inconsistent flow (abnormal pressure surges). In either case, there’s a problem.

Causes

It’s worth noting that the flow inconsistencies themselves may cause the detected pressure changes or the other way around. It’s also worth noting that both can be a symptom of a separate problem. Check for debris in your system that could disrupt the intended flow. Also check where that debris comes from, as it may consist of loose internal parts and therefore indicate other system issues. Additionally, low fluid pressure can lead to flow issues because your check valve may not be opening and closing properly.

Risk Factors

Backflow can be damaging and lead to leakages as fluid is getting in and staying in places it’s not supposed to be. Inconsistent or low flow is highly inefficient and wastes energy, which is costly. If you don’t address these issues, you won’t catch any underlying debris that can damage your system in other ways as well.

Solutions

Clean your tubing or pipes (as the case may be). Check that your inline filtration components are doing their job. Outside of these, make sure your system’s flow pressure (PSI) is enough for the cracking pressure of your chosen valve. In other words, your valve needs a certain amount of pressure to open and close properly. There is such a thing as too little. If you need flexibility in your cracking pressure, consider a spring loaded check valve, which allows for variability.

4. Sticking

Valves sometimes get stuck in certain positions, causing them to fail to open or close fully, consistently, or at all.

Causes

Valves stick for a range of reasons. Debris from loose valve pieces or other parts of your system can get inside the valve’s body bore and restrict movement. Valves also stick because of general wear, especially if their elastomers start to corrode. In other words, those stretchy components keeping your valve mobile and fluid-tight don’t stay stretchy forever. Finally, valves with highly mobile components, like ball check valves, will find those components (i.e. the ball) sticking when it shouldn’t.

Risk Factors

Sticking valves will result in pressure fluctuations like those described above. Catching the sticking valve early will help mitigate further damage to the system. Similarly, if the sticking is caused by debris, that could be indicative of tangential issues. Maybe there’s component damage in other parts of your system. Or maybe you just need to check, clean, or replace your filters.

Solution

This depends on the cause. If there is debris, then clean it out. Check what it is and if there could be damage elsewhere. If the valve itself is starting to corrode, then consider whether you can replace a specific part or need to replace the entire thing. Also consider whether your system would benefit from inline filtration in front of your check valve (if you don’t already use it).

5. Leaking

Fluid is escaping your valve either externally or internally. Depending on the system, the leaking may sound like a hiss or result in significant condensation. In either case, you’re going to notice pressure changes alongside it. When this leakage is due to air flowing past the valve seal, it’s commonly referred to as bypass.

Causes

Damaged seat seals are a common cause of leaking, particularly bypass. These components become damaged in a variety of ways, including low inlet pressure that fails to crack the check valve, fluids seeping through the shutoff valve, or simple wear and tear due to friction over time. That said, bypass is not exclusively a seal issue, also check for cracked housing or a dislodged valve insert. And of course, debris in the system preventing the check valve from closing properly will cause leaking as well.

Risk Factors

While seat seals come in a range of materials, from stainless steel to various polymers, their job is the same – to prevent leakage. As they fail, the resulting issues are predictable. Leaking causes pressure reduction and inconsistency, which can lead to system damage or energy waste. Your check valve has one job – keep fluid going in the intended direction. Make sure it’s not sleeping on the job.

Solution

Don’t assume it’s the seat seal. Test your system to determine the origin of the leak and any underlying causes. Many leakage issues can be valve specific. Duckbill check valves, for example, rely on a fine, stretchy insert that loses elasticity over time. Diaphragm valves utilize a flexible disc to create a seal for blocking or allowing flow, which when damaged will no longer seal properly. In the case of miniature plastic check valves, the components are reasonably priced and easy to replace. Some larger check valves may contain replaceable components.

6. Excessive Wear and Damage

The unfortunate truth is that check valves get old. Parts need to be replaced. Make sure you’re checking your equipment for wear as a matter of principle. This often looks like corrosion around the outside of the check valve, including rust on metal check valves, even sometimes stainless steel valves. However, it may not be as obvious in some cases. Worn elastomers, for example, are harder to spot at a glance. A good rule of thumb is to replace elastomer-based valves every 5 years while those without elastomers can last upwards of 20 years in the right conditions. In either case, if you feel the wear is excessive for the check valve’s age, investigate the cause.

Causes

Outside of typical aging, your check valve may be worn out due to high operating temperatures. High temps lead to expansion and, by extension, faster degradation. It also compromises the integrity and efficacy of seals, making it another potential cause of leakage. Also check that the material that your check valve is made from is compatible with the fluid that flows through it. Incompatible materials accelerate corrosion.

Risk Factors

Put simply, the more degraded your check valve becomes, the greater the risk of equipment failure. Don’t put off until tomorrow what you can clean, lubricate, or replace today.

Solutions

Make sure you are maintaining your valves properly. This starts with ensuring you are using the right valve for the right situation, including cracking pressure and chemical compatibility situations, and extends to keeping those valves clean and lubricated. You’ll also want to check that the valve is installed properly. Of course, preventative measures such as these may or may not help when your check valve has degraded to a certain point. However, they are important considerations for any replacement parts or valves you use in the future.

What Now?

The simple truth is that many check valves are set up to fail because they are not the right valves for the job, were installed improperly, or weren’t maintained well. Just replacing your check valve won’t fix these issues. Whether you’re investigating chemical compatibility, checking what cracking pressure you require, or learning about complementary components, like inline filters, that will protect your check valves from obstruction, the right supplier can help.

Get your next check valve from a company that will guide you in making the best choices for your needs and answer your technical questions along the way. ISM is more than just a supplier; we are a partner that can help you find the right high-quality part for your needs.