Check Valves

Check valves are fittings used in a variety of applications to prevent liquids or gases from flowing backwards. They are often used in piping systems, pumps and containers to ensure that the medium can only flow in one direction.

Check valves consist of a valve seat, a valve cone or ball and a spring or other mechanism that holds the valve in a closed position. When the medium flows in the right direction, the valve opens and allows the flow. However, if the medium tries to flow in the opposite direction, the valve closes and prevents backflow.

There are different types of check valves such as ball valves, poppet valves and swing arm valves. Each has its own specific applications and limitations. Ball valves, for example, are best suited for use in high-pressure applications, while poppet valves have proven themselves at lower pressures.

Check valves are essential in many industrial applications, as they help to ensure the safety and efficiency of piping systems. They also prevent damage to equipment and reduce the need for repairs and maintenance.

Check valves consist of several important components which work together to prevent the backflow of liquids or gases. The key components of a check valve are:

Valve seat: The valve seat is the part of the valve that the valve part rests against. It is the part responsible for keeping the valve securely in the closed position when not in use.

Valve section: The valve section is the part of the valve that moves to allow or prevent the flow of the medium. It can be in the shape of a cone or a ball. In ball valves, the valve part is a ball suspended in a ball retainer. This ball can rotate in a plane, to allow or prevent the flow of the medium. In poppet valves, the valve part sits on the valve seat and moves up and down to allow or prevent the flow of the medium.

Spring or other mechanism: To keep the valve part in the closed position when not in use, check valves usually deploy a spring or another kind of mechanism to keep the valve section under pressure. When the medium flows in the right direction, it overcomes the pressure of the spring and opens the valve. However, if the medium flows in the opposite direction, it is pushed back by the spring, and the valve remains closed.

Some check valves also have additional components such as seals, to ensure that the medium does not escape through the valve parts. These seals can be made of rubber, PTFE or other materials.

What are the areas of application for check valves?

The valves have the following areas of application:

• Chemical industry
• Petrochemical industry
• Maritime technology
• Water treatment
• Sewage treatment plants
• Nuclear power plants
• Boiler feed

Can a check valve shut off?

In the lockable check valve, the functions of shut-off valve and check valve are combined. There are different special designs of check valves such as ball check valves, safety valves or overflow valves. In an overflow valve, for example, a spring or weight-loaded plug opens at a certain overpressure and relieves the system.

What types of connection are there?

Check valves have different connection types depending on the series.
The following list shows different variants of the valves:

• With flange connection
• With weld ends
• With threaded sockets
• With welding sockets

Which check valves are there?

Check valves differ depending on the design and manufacturer.
The following list shows a selection of check valves:

• Flange check valves
• Flange ball check valves
• Threaded ball check valves
• Sleeve check valves
• Intermediate valve
• Spring-loaded check valves
• Shut-off check valves
• SAE check valves
• Unlockable check valves

Can a check valve be used for gaseous media?

In addition to water and steam, the valves are also suitable for gaseous media or oils. The check valve housing material plays an important role here.

What is a check valve material housing made of?

The valves are available in the following materials:

• Stainless steel
• Cast steel
• Grey cast iron
• Gunmetal (2.1096 / CC491K)
• Spheroidal iron
• Bronze G-CuSn10
• Brass
• Special brass
• Niro

What position are check valves installed in?

The position check valves are installed in can vary depending on the design. Let's take the GESTRA DISCO check valve as an example: Here, the installation position is basically random. However, if the fitting is supplied without a closing spring, installation is restricted to the vertical position. Why? Because here, the direction of flow of the medium is “upwards”.

Check valves in line with German Gas and Water Association (DVGW) approval

Are check valves certified in line with the regulations of the German Gas and Water Association? For certifications by the German Gas and Water Association( DVGW), neutrality, quality and reliability are the top priority. For example, our check valves have DVGW approval. The free-flow slanted-seat check valve is an example of a DVGW-approved check valve. This certification is particularly important for fittings in drinking water pipes, among other things. This is also referred to as an additional DIN-DVGW test.

Check valves according to Technical Instructions on Air Quality Control (TA-Luft) approval

According to the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, we are also able to certify fittings with TA-Luft approval. TA-Luft stands for Technical Instructions on Air Quality Control. Here is an overviewof all our approvals.