Check Valve History
Frank P. Cotter invented the first check valve. In 1907, he developed a check valve that was very easy to install, repair, and inspect. Nikola Tesla (in 1916) invented another kind of check valve which he called the Tesla valve. The tesla valve was patented in 1920, and it was a simple unidirectional fluid valve.
Nowadays, technology has become so advanced that plastic diaphragm check valves are also present. These are used in the field of medicine.
Check Valve Working Principle
The specialty of check valves is that they are self-automated and are one of the few valves that don’t need a human being to cycle them. They are sensitive to flow and take the help of the media to open and close their seat.
The working principle of the check valves is quite simple. The valve allows the fluids to flow in one direction while simultaneously stopping its flow in the opposite direction. The disc inside lets the fluids flow in the forward direction forcing the valve to open. When the flow reverses, the valve closes.
Check Valve Construction
A necessary check valve components include a valve body, a disc, and a bonnet/cover. The disc is attached to a hinge, making it sway away from the seat and allows the fluid or media to flow forwards. The disc falls back to the valve seat when the fluid stops flowing upstream. In this way, the backward flow is prevented.
Folding disc check valves consist of two equal parts or halves that are joined at the centre. The two halves are activated by springs. When the upstream flow starts, the discs fold backward. They close the flow immediately when the upstream flow stops.
In lift check valves, the disc is like a piston. The piston/disc moves away from the path of flow when the flow is upstream. But it returns to its original position when the flow stops being upstream. Gravity is the force that helps prevent backflow.
Then we have ball check valves that use a ball for a disc. The size range is from NPS ¹⁄₄ (DN 6) to NPS 72 (DN 1800). There may also be other available if one wants to meet specific size requirements. Components of a check valve depend on the needs of the piping system. According to these needs, the check valves may include socket welding, threaded ends, flanged ends, etc.
Check Valve Types
1. Swing check valves
The first type of check valves is the swing check valve. This valve consists of a disc that swings or sways on a hinge. When the disc swings off the seat, forward flow occurs. But when the flow stops, the disc sways back to the seat. In this way, it prevents backward flow.
Swing check valves which include levers and weights are more suitable for conditions where there is a fear of the water hammer effect. For high pressure, high velocity, and inadequate back-pressure situations, swing check hammers with lever and external springs are used.
2. Ball check valve
In a ball check valve, a ball is present instead of a disc. This ball prevents backward flow by being lifted out of the outlet. This happens where the ball experiences pressure from the flow. As the pressure level lowers, the ball falls back to its original position and stops backward flow.
3. Double check valve
The double check valve usually finds its use in applications where water supplies need to be protected from contamination. The DC valve is a check valve consisting of two check valves aligned in a series manner. Two principles are used here:
The first principle of operation is that one check valve will work even if the other is jammed open.
The second principle of operation is that when one valve closes, the pressure is reduced. This makes a more reliable seal and avoids leakage.
4. Lift check valve
Lift check valves are quite similar to globe valves and have the same arrangements. Therefore they can be used in all the piping systems where globe walls are used. The disc is in the form of pistons or balls whereas the seat is similar to the globe valve. These valves are suitable for services where pressure and velocity of service are high. The disc fits perfectly into the dashpot.
The fluid in lift check valves must always enter from under the seat, and this will cause the piston or ball to rise by the pressure of the upward flow. And the piston or ball returns to its seat whenever the flow stops. This is mainly due to the effect of gravity.
The lift check valves are available in different body patterns such as horizontal, angular, and vertical body patterns.
5. Dual check valve
The dual check valve or butterfly valve consists of a disc divided into two parts along a middle line. The two doors open and close through a hinge. This valve also supports forward flow and prevents backflow. As this valve is small and relatively lightweight, it is very suitable for low-pressure services.
6. Piston check valve
The piston check valve is a type of lift check valve. The dashpot of the piston check-valve contains a piston as well as a cylinder. This dashpot acts as a cushion during its operation. The design is quite similar to lift check valves, so the flow is essentially the same.
7. Stop check valve
The stop check valve is a mixture of the lift check valve and globe valve. The stop check valve controls the flow irrespective of the direction of flow. Instead of gravity, this valve can be closed by an external mechanism. So flow occurs here regardless of the flow levels (whether forwards or backward). The stop check valve is useful to protect equipment from damages.
8. Tilting disc check valve
The tilting disc check valve is like a swing check valve except that it is assisted by a spring. The media is found flowing around it. The tilting disc check valve is available in the lug design and wafer design, and it tilts up when the fluid flow gives it a steady pressure. When the flow level decreases, the disc goes back to its initial position.
9. Other Check Valve Types
Silent Check Valves, Butterfly Check Valves, and more.
Check Valves Materials
The method, temperatures, pressures, and flows need to be understood. All this data helps to decide the correct spring adjustments and orientations so that the valve functions appropriately for usage. And the corrosive nature of the media undoubtedly helps determine the kind of content that should be used.
Below are among the most popular materials for the check valve and their benefits.
- 316 Stainless Steel-Stainless steel is a corrosion-resistant material that is the most common material for volume-based check valves. It remains reasonably rust-free in conditions such as water and humid air, and steam. With regard to its corrosion-resistant qualities, it is a comparatively low-cost material.
- Carbon Steel-Carbon Steel is a material that is simpler for the system at a lower price. All in all, with the use of carbon steel, prices can be minimized, but it does not have the same corrosion-resistant characteristics as stainless steel. If the usage is in a dried setting, such as dry gas or hydraulic fluid with no water, then carbon steel is productive, and stainless steel does not have to pay more money.
- Brass- Brass lies somewhere between carbon and stainless steel in several implementations when it comes to corrosion resistance and cost. Brass against carbon steel has some extra corrosion-resistant attributes and is more straightforward to process than stainless steel. Brass is also used in processes requiring water and drinkable water.
- Monel-Monel is a nickel alloy category and is deemed to be a superalloy. Extreme corrosion resistance is the most significant benefit. In saline, salt, or marine water settings, Monel is rightly regarded to be successful. Each superalloy has various resistant properties to chemicals. Most do quite well in one setting where others in a particular environment may do well.
- Alloy 20- This austenitic alloy is considered by many to be a blend of stainless steel and other superalloys. Usually, it is not as costly as certain superalloys, but in some cases, it is more highly corrosion-resistant than conventional stainless steel.
- Alloy c-276-Alloy c-276 is a solid nickel-molybdenum-chromium mixture reinforced solution with a tiny portion of tungsten. In a range of extreme conditions and media, it demonstrates excellent corrosion resistance. It is ductile, readily formed, and soldered, like other nickel alloys. It is used in certain industrial settings where there are hostile chemical conditions, and other alloys have collapsed.
- Titanium-Titanium is an alloy at significantly elevated temperatures that are used.
- Inconel-It is an austenitic superalloy based on nickel-chromium. It is a corrosion-resistant oxidation substance well adapted to heat and pressure in hostile climates. When clients want something close to stainless, this can also be utilized.
Check Valve Applications
Check valves are advantageous and can be used in the following areas:
- Flood prevention
- Hydrocarbon processing
- Boiler systems
- Power plants
- Petroleum production
- Petroleum refining
- Gel mini-pump dispensers
- High-pressure safety services.
- Spray devices
- Air pumps etc.
Check Valve Advantages and Disadvantages
Check Valve Advantages:
- Check valves can help prevent the water hammer effect.
- The low-pressure drop caused by check valves helps save energy.
- These valves prevent chatter.
- Check valves cause a reduction in downtime.
- Low production due to failure of valves is prevented through check valves.
- The possibility of valve failure is significantly reduced through check valves.
- Check valves protect equipment such as pumps and compressors from damages due to backward flow.
- Check valves have low maintenance costs because they have lesser mobile parts.
- The footprints are smaller than conventional check valves.
- Check valves can be used interchangeably with swing check valves without a lot of changes and modifications.
- Check valves are capable of dealing with all kinds of flow conditions.
Check Valve Disadvantages:
- Check valves can’t run in a pulsating system.
- Run in a completely closed system.
- The disk may be stuck in the open position.
- The closing element may close suddenly, causing damage and wear.
- There is no way to check whether they are open or closed.
- The internal parts of the check valves cannot be inspected.
Check Valve Installation Instructions
The following are some things you need to be careful about during the installation of a check valve.
First of all, selecting the right valve should be your priority. The wrong valve might cause inefficiencies or wear and tear of the valve. The valve should be selected in relation to the pipe’s size, orientation, direction, material, etc.
Secondly, you should be careful about the area you install your valve at. All check valves don’t work vertically. Also, make sure that the check valve is about 5 pipe diameters away from anything that might cause turbulence. For example, you should keep the valves away from elbows, fittings, or any other valves.
You should also keep the orientation proper by keeping an eye on the flow arrow. This flow arrow is usually found printed on a tag or marked on the valve.
Maintenance of Check Valve
Check valves are usually very low maintenance and will last you many years. However, sometimes impurities or debris may clog the area between the disc/ball and seat. This clogging can result in loss of mobility and ultimately, the degradation of the valve. To prevent that, you can use the following steps:
The most obvious solution to preventing debris accumulation is cleanliness. You can keep your check valve clean by gently wiping away the dust and dirt. You can use a wire brush to take it off if it is caked on. Disassemble the whole check valve and wash all of the parts separately using a hydraulic liquid.
2. Keep an eye out/ Inspection
Inspect your check valves thoroughly. It’s always better to inspect and diagnose problems early instead of paying for heavy repairs later on.
The following are the things you need to look out for during your inspection session:
Check for leakage.
Open and close the valves to ensure mobility.
Keep an eye on the pressure and temperature going through the fluid.
Replace any broken parts
Check for corrosion, minerals build-up, or even rust.
3. Keep the valve lubricated.
Lubrication is a significant step that ensures mobility and increases the useful life of the check valves. You can rotate the valve to ensure that the lubricant slides into the cavity and reaches all the desired areas. Picking the right lubricant is also crucial because each system has its own needs. So using the wrong lubricant may cause harm to the check valve.
4. Apply protective insulation.
Insulation is vital because drastic temperature changes affect the functioning of the check valves. The damage may sometimes be very intense and cost you fortunes to repair.
Why Choose DBV Check Valve Manufacturer?
Why buy or wholesale check valves from us? Here are the reasons:
- Rice experience and quality guarantee: As a manufacturer with 14 years of experience, DBV has refined and vertically integrated the valve design and manufacturing processes to assure the highest standards of quality control at each step of our check valve manufacturing process. Our customers come from all over the world including the USA, Japan, UK, Canada, Australia, France, Norway, Russia, and so on.
- Affordable prices: DBV check valve supplier has own manufacturing plants in China, so competitive factory-direct prices are available.
- Professional OEM/ODM service: DBV check valve manufacturer understands that our clients are from diverse industries, so our company offers one-stop Custom Check Valve manufacturing service to meet different industrials and demands.