File Name: check valve types and applications .zip
Check valves are designed to pass flow in one direction with minimum resistance and to prevent reverse or back flow with minimal leakage. The principal types of check valves used are the tee-pattern lift check, the swing check, the tilting-disc check, the Wye-pattern lift check, and the ball check, illustrated in Figs.
- How to choose the right check valve
- Check Valves
- Check Valve: Types, Working, Application, Symbols, Materials (With PDF)
The pressure of the fluid passing through a system opens the valve, while any reversal of flow will close the valve. Exact operation will vary depending on the type of Check valve mechanism.
How to choose the right check valve
Check valves are mechanical devices used in piping and pipeline systems to prevent back-flow. Check Valve works on the principle of differential pressure. It means the check valve will only open if upstream pressure is more than the downstream pressure. In situations, if downstream pressure is more, the valve will close preventing back-flow. One of the main applications of check valves is at the pump outlet to protect the equipment from flow-reversal.
Check valves are automatic valves and unlike other valves, human intervention or external control is not required for their opening or closing. The only purpose of the check valve is to prevent flow reversal or back-flow and they are available in various sizes, designs, and materials. As already stated that a check valve operates on the principle of differential pressure. For a check valve to open, it must attain a minimum upstream pressure known as cracking pressure. Depending on the check valve design and size, the cracking pressure changes.
When the upstream pressure reaches the cracking pressure, the valve opens allowing the fluid to enter. When the upstream pressure falls below the cracking pressure, back pressure is generated and the flow attempt to move from outlet to inlet. At this point, the check valve closes, and the flow halts. The closing mechanism of a check valve varies depending on the design and type of the valve. Spring or Gravity pressure normally assist the closing process. As the check valve works only in one direction, manufacturers provide an arrow on the valve body indicating the flow direction.
A swing check valve is the most widely used check valve. The closing member or the disc swings on a hinge or shaft. To allow the flow, the disc swings off the seat and it swings back onto the seat to block the reverse flow. In an open position, a swing check valve offers very little resistance to the flow. To achieve optimum performance, often a lever and weight or a lever and spring are mounted.
The disc weight and the return flow has an impact on the shut-off characteristics of the valve. The following animation video explains the main parts and working methodology of a typical Swing Check Valve.
Wafer check valves are very slim and compact in design and use a swinging disc to allow or block flow. They are lightweight and suitable for various applications. They are economical and are available in various sizes. The following figure shows the typical working of a Wafer Check Valve.
Wafer check valves are ideal for services requiring low pressure loss as the valve operation takes place at very low pressure difference. These valves employ a centrally guided stem-disc assembly along with a compression spring.
To open the valve, the flow pressure must be more than the spring force and cracking pressure. In that case, the flow pushes the disc allowing the flow. When the inlet pressure reduces, the spring pushes the disc against the orifice and shut the valve. The operating principle of Spring-loaded y-check valves are similar to in-line check valves.
The main advantage of Y type check valves is that it can be inspected and serviced while the valve is still connected to the system. Ball check valves are simple in operation and commonly used on small pumps and in low head systems. Ball check valves involve a spring-loaded or free-floating spherical ball clapper to shut at pressures below the cracking pressure. In order to guide the ball into the seat and create a positive seal, the sealing seat is conically tapered.
However, these valves can easily wear due to prolonged use and require frequent maintenance. Diaphragm check valves consist of rubber flexing diaphragms or self-centering discs for preventing backflow. When the inlet pressure is increased, the diaphragm flexes open and flow start.
There are two types of the diaphragm check valves;. In the case of normally open diaphragm valves, no cracking pressure is required as the self-centering elastomeric diaphragm is free-floating. However, they need back pressure to close the valve. On the other hand, normally closed valves need a certain inlet pressure to overcome the elasticity of the fixed diaphragm. Due to very low cracking pressure, Diaphragm check valves finds its use in low pressure and vacuum applications.
A lift check valve is also known as piston check valve. It consists of a guided disc that raises lifts up from the valve seat and creating space for media to flow. The valve will close when the inlet pressure decreases below the cracking pressure or there is a back-pressure.
A stop-check valve is basically, two valves built into one body. It can act as a globe valve for isolation or regulation purpose. Again, It can acts as a check valve to prevent back flow. Contrary to other check valves, Stop check valve has an additional external control mechanism in perpendicular or angular direction.
Stop Check valves are popular in steam services like power plants, boiler circulation, steam generators, turbine cooling and safety systems. A foot valve is a check valve which has a strainer installed on the inlet side to prevent the debris entering into the valve.
Duckbill Check Valves are unique, one-piece, elastomeric components that enable flow to proceed through a soft tube that feeds into the downstream side of the valve wherein back pressure collapses the tube and cuts off the flow. Non-slam check valves are specifically designed valves where the closing member close without slamming preventing excess pressure spikes. The disc of a non-slam check valve includes an internal spring opposing the opening fluid flow pressure.
When the flow media is strong enough, the spring compresses and the valve opens. Again when the flow decreases, the disc is smoothly pushed back toward the valve seating surface by the spring force and stops.
For vertical piping runs or complex applications requiring constant and controllable pressure levels, Non-slam check valves are an ideal solution. The main advantage of non-slam check valves is their ability to effectively prevent water hammer. Hence, pressure swings, vibrations, and component damages are ideally eliminated. As Non-slam valves have a short stroke, they facilitate quick soft closing of the disc to prevent water hammer.
As they consist of only one moving part, the disc itself, non-slam check valves experience minimal wear over time. However, the non-slam check valves are not piggable. Dual-plate check valves are wafer-type compact valves with a small overall length. They provide excellent hydrodynamic properties that result in very low-pressure losses and they are technically efficient.
Their low weight provides advantages during installation, transport, and storage. Dual-Plate check valves are suitable for liquid, gas, steam, condensate, water supply, and in oil and natural gas services.
They are designed as non-slam type. With suitable springs, they can be installed in any position. The symbol of check valve can vary slightly from company to company. Normally any one of the following check valve symbols are prevalent in industries. Few typical applications are shown below:. Click here to learn about various types of Valves. I am a Mechanical Engineer turned into a Piping Engineer. I am very much passionate about blogging and always tried to do unique things.
This website is my first venture into the world of blogging with the aim of connecting with other piping engineers around the world. Greeting of the day I am Instrumentation and Automation engineer. Working with paper industry. Really wonderful material. Good technical information. Thanks a lot for your technical service. Guru rajan ISRO. Hello, kindly forward quotations technical specification shipment for each of your valves, look forward for your kind response.
Best regards, Lewis Michael. Sir can you provide guidance for mechanical engineer who wants to switch job and come into this industry. Means exactly what skills should one learn in order to join this industry. Your email address will not be published. Save my name and email in this browser for the next time I comment.
ASME U stamp is What is a Drip Leg in Steam Piping? Drip Legs are vertical piping pockets installed in steam piping to collect condensate. Installing drip legs in the proper location serves the purpose of a Skip to content Table of Contents. Working of Check Valves As already stated that a check valve operates on the principle of differential pressure. Types of Check Valves Depending on the movement of the closure member, various types of check valves are available.
Swing Check Valve. Wafer Check Valve.
The valve that used to prevent backflow in a piping system is known as a check valve. It is also known as a non-return valve or NRV. The pressure of the fluid passing through a pipeline opens the valve, while any reversal of flow will close the valve. It allows full unobstructed flow and automatically shuts as pressure decreases. The exact operation will vary depending on the mechanism of the valve. It is consists of body, cover, disk, hinge pin, and seat ring. In the image below you can see the parts of the valve.
In general, ball check valves are simple and cost effective. Advantages are their compactness and the fact that they have no external parts which helps keeping the price low and the reliability high. For more details, please visit the section about ball check valves. Swing check valves are the most common check valves. They are inexpensive and as they are automatic they do not require any external power or control to operate — only the flow direction determines the valve operation. For more details, please visit the section about swing check valves. The tilting disc check valve is similar in appearance to an eccentric butterfly valve.
Check valves are one of the most important valves for any system, whether for industrial equipment or a household item. However, types of check valves are designed for a specific application. Contact The Valve Experts. Swing check valves feature a simple design complete with a disc attached to a hinge at the top. As fluid passes through, the valve remains open. When a reverse flow occurs, the changes in motion as well as gravity help to bring down the disc, effectively closing the valve. These types of check valves are commonly used for firefighting and flood prevention in sewage systems.
Check Valve: Types, Working, Application, Symbols, Materials (With PDF)
RITAG industrial valves for any application Whether as a standard product or as a custom order: RITAG wafer type check valves are available in any nominal diameter, pressure level and material for your processes. The development and manufacture of our high-quality valves are in compliance with all international standards and regulations. Some of the most common areas of application are hot water plants, plants for water and waste water treatment, boilers and supply systems, energy pipe systems and process equipment for the chemical and petrochemical industries. Our standard product range already takes care of the most important application ranges.
A check valve, or one-way valve, is designed to allow fluid to flow through it in only one direction. They are ideal where back-flow could potentially cause damage to pumps, filters, or process equipment. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to exit.
A check valve , non-return valve , reflux valve , retention valve , foot valve , or one-way valve is a valve that normally allows fluid liquid or gas to flow through it in only one direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave. There are various types of check valves used in a wide variety of applications. Check valves are often part of common household items. Although they are available in a wide range of sizes and costs, check valves generally are very small, simple, and inexpensive.
Check valves are mechanical devices used in piping and pipeline systems to prevent back-flow.
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Many different types of manual valves are used in industrial applications worldwide. The following article will cover the general mechanism and function of the most typical of these valves used in steam systems, such as ball valves , butterfly valves , globe valves , gate valves , and diaphragm valves. For further details jump down to: ball valve , butterfly valve. Ball valves offer very good shut-off capabilities. This characteristic minimizes valve operation time and decreases the likelihood of leakage due to wear from the gland seal. Ball valves can be divided into two categories: reduced bore and full bore. In reduced bore valves, the valve opening is smaller than the diameter of the piping; in full bore valves, the valve opening is the same size as the diameter of the piping.
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