Check valves are an important type of valve for many industrial and home projects. This type of valve is designed to help prevent backflow within the system as well as maintain a steady level of pressure. Check valves are commonly used to help regulate the flow of liquids and gases. They are used in a vast number of different industries, including refining, chemical, water, and waste-water management, as well as in manufacturing systems. There are a number of different check valves that are currently available on the market, such as ball, swing, and wafer. Swing check and wafer check valves have the same function but are very different in design. Their differences commonly dictate what type of situations or systems require which type of valve.
Swing Check Valves
Swing check valves use a swinging disc, which is meant to allow or block the flow of materials. Swing check valves are designed to be self-activating, meaning they allow and block the flow of materials without user interference. The design of the swing check valve allows for full flow of materials. This is because the molded body of the valve is shaped with room for the disc to swing open completely. This is very important if full flow is needed in the system the valve is being used in, making swing check valves ideal in situations where a full port valve is needed.
How They Work
Swing check valves function utilizing a disc and a hinge which are then suspended from the top of the unit using a hinge pin. As material passes through the unit, the disk remains parallel with the flow, keeping the valve open. When reverse flow of material occurs, the disc moves down perpendicular to the flow of material, which results in the valve closing.
These valves are available in two common shapes: a straight body design or a Y-shaped design. Either shape can be advantageous depending on the situation or setting the valve is being used in.
Advantages and Disadvantages
Swing check valves come with a number of advantages and disadvantages. On the positive side, turbulence and pressure drop among materials being passed through the valve is very low. The seat rings are also replaceable in swing check valves, meaning the entire component need not be replaced if something happens to the seating ring. Swing check valves also have an angled seating surface. This characteristic permits easier opening of the valve even at lower pressures. This angle is also what helps trigger gravity, in the event of a backflow which helps close the valve. This type of valve also has more positive sealing and experiences lower levels of shock even under high pressure.
On the other hand, swing check valves are not able to be used in systems with pulsating flow. Instead, material flow needs to be continuous. Otherwise, the continued flapping of the valve would damage the seating elements.
Applications
Swing check valves are commonly used in household systems, like toilet tanks for example. They are also used in instances of firefighting and within flood prevention applications in sewer systems. Swing check valves are meant to work with a number of different materials, including gases and liquids.
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Wafer Check Valves
Wafer check valves are named such for their compact size. The small size of the valve enables it to be set between a set of flanges. Flanges are materials designed to connect pipes, valves, and various piping equipment for the purpose of creating a piping system. They help to provide quick access in case cleaning or other maintenance is needed.
How They Work
The valves wafer-like profile makes it a great choice for systems requiring short takeout lengths. Wafer check valves work much in the same way as swing check valves. Like swing check valves, wafer check valves are comprised of a disc and a seating arrangement. When material flows in one direction, the flow lifts the disc from the seating arrangement. This allows material to flow through the valve. If and when flow reverses direction through the valve, the flow of material pushes the disc back into the seating arrangement, thus closing the valve off from the flow of material.
Wafer check valves are designed to be slim and unlikely to clog. This design makes them ideal for use with materials containing solid particles or debris. This type of valve can be mounted either vertically or horizontally, as long as the back pressure required to seat the check valve is sufficient. Mechanisms are available to help provide assist valves in case back-pressure is insufficient.
Applications
Wafer check valves are able to be used in a number of different applications. These include use in chemical processing, power plants, and mining. On a household level, these types of valves are also used in tank inlet/outlet, aquariums, and swimming pools.
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Determining the Type of Check Valve Needed
When it comes to deciding what type of check valve is correct to use, the answer depends entirely on the situation. It is important to remember key facts about each type of valve when making your decision. For example, swing check valves are not meant to be used with pulsating flows of materials but are designed for systems which require full port valves. Wafer check valves are designed to fit into small spaces between two flanges, where swing check valves may not fit. One other major difference between swing check and wafer check valves is the wafer check valve restricts flow by a greater percentage than the swing check valve. Wafer check valves are also meant for systems with materials with suspended debris, as they are unlikely to become clogged.