Flap check valves Manufacturers online

Flap check valves are valves that allow the flow of a medium in one direction and automatically block it in the opposite direction with the aid of a movable flap that opens due to the pressure of the flow and closes in the event of backflow.

They therefore prevent backflow in the pipe system. They are self-acting and therefore do not require an external energy source or control.

Below is an overview of the function, types and use of flap check valves, their advantages and disadvantages as well as existing limitations:

How flap check valves work:

The operating principle is simple:

1. In the direction of flow, a movable closing element, e.g. flap, ball or disc, is opened by the pressure of the medium.
2. If the pressure drops or a back pressure is created, the medium or a spring automatically pushes the closing element back into the seated position, thus blocking the return flow in the line.
3. Flap check valves thus protect pumps, compressors, lines and systems from backflow, pressure surges and damage.

Types of flap check valves:

There are various types, which differ in design and intended use:

1. Swing check valve:
   A pivoted flap plate swings open when the medium flows and closes when the medium flows back.
   Particularly suitable for larger pipe diameters and liquids.
2. Double blade non-return valve:
   Two vanes on a shaft open in the direction of flow and close on backflow.
   Compact design, low pressure loss, often used in industrial and HVAC applications.
3. Disc check valve:
   A disk lifts during flow and sits on the valve seat during backflow.
   Suitable for smaller nominal sizes and higher pressure.
4. Non-return valve (waste water):
   
   These are specially designed for use in wastewater pipes to prevent wastewater from pushing back into the building when the sewer system is overloaded. They can be purely mechanical with pendulum flaps or motorized.
5. Spring-loaded non-return flap:
   An additional spring supports the closing of the element, ensures fast closing and prevents water hammers.
   Suitable for horizontal and vertical pipes.
6. Wafer-type non-return valve:
   A particularly space-saving design that is mounted between flanges.
   Frequently used in building services, pumping stations, heating and cooling systems.

Areas of application for flap check valves:

Flap check valves are standard wherever a medium may only flow in one direction.

1. Water supply and waste water technology:
Flap check valves are standard in pumping stations, drinking water pipes and waste water systems.
They prevent pumped water from flowing back when the pump stops and damaging pumps or pipes.
Example: Well pumps, sewage lifting stations, pressure boosting systems.

2. Heating, ventilation and air conditioning technology (HVAC):
In heating and cooling circuits, flap check valves ensure that media, e.g. hot water, cold water, do not flow back and that circuits do not influence each other.
They also prevent backflow of air or refrigerants in ventilation and air conditioning systems.

3. Oil and gas industry:
In pipelines, tank systems and pumping stations, flap check valves prevent dangerous backflows of oil, gas or fuels.
They protect pumps and compressors and prevent pressure surges when changing direction.

4. Chemical and process industry:
In chemical processes or dosing systems, flap check valves the mixing of different media or chemicals.
They are often available in corrosion-resistant materials (e.g. stainless steel or PTFE).

5. Fire protection and extinguishing systems:
In sprinkler systems, hydrant lines or foam extinguishing systems, flap check valves secure the water pressure and prevent contamination of the drinking water network by extinguishing water.

6. Shipping and offshore technology:
On ships and offshore platforms, flap check valves protect pump and piping systems from backflow of ballast water, cooling water or oil.
They are important for safety and operational continuity.

Advantages of flap check valves:

• Automatic operation: No power or control required.
• System protection: Prevents backflow, pressure surges and damage to pumps or compressors.
• Simple installation: Many designs can be integrated into existing systems.
• Low maintenance: Robust designs, often long service life.
• Large selection of materials and designs: Suitable for water, gas, chemicals, oils.
• Flexibility: Horizontal or vertical installation possible (depending on type).

Flap check valves are indispensable safety elements in pipelines. They work automatically and reliably to prevent media backflow and protect systems. Thanks to the wide range of designs - from the simple swing check valve to the spring-loaded intermediate flange design - there is a suitable solution for almost every application. Their advantages lie in their reliability, protective effect, low maintenance and simple integration.

Here is an overview of the most important criteria to look out for when purchasing flap check valves:

Flap check valves reliably prevent the backflow of liquids or gases and thus protect pumps, compressors, pipes and entire systems from damage and malfunctions. As they are often safety-relevant in critical processes and must function reliably in the long term, careful selection is crucial when purchasing. Not only price and size, but also design, material, operating conditions and ease of maintenance play a role.

• Before making a selection, it should be clear which medium will be flowing through: Water, oil, gas, chemicals, steam or air.
• Chemicals and aggressive media require corrosion-resistant materials such as stainless steel, Hastelloy or PTFE linings.
• The choice of the right design depends on the flow rate, medium and installation position:
• Swing check valves for large nominal sizes and low pressure loss.
• Double-wing or wafer-type butterfly valves for space-saving installation and low weight.
• Disc check valves for small nominal sizes and high pressures.
• Ball check valves for contaminated media.
• Spring-loaded versions for fast closing and prevention of pressure surges.
• Food or pharmaceuticals require hygienic materials and smooth inner surfaces.
• Media containing solids, e.g. waste water, require designs that are insensitive to contamination, e.g. ball check valves.
• The flap check valve must safely withstand the maximum operating pressure and the highest operating temperature:
• Check the nominal pressure (PN) and pressure peaks, e.g. when starting the pump.
• Pay attention to temperature tolerances, cold and hot water, steam or cryogenics.
• With frequent switching or high frequencies, spring loads or damping can be useful to prevent water hammer.
• Not every flap check valve works in every installation position:
• Check whether the valve may be installed horizontally, vertically or in any position.
• Take into account the space required for installation and maintenance.
• Wafer or wafer designs are often more compact and lighter than flanged valves.
• An important factor is the pressure loss of the valve when open:
• Low pressure loss saves energy and reduces operating costs.
• For large flow rates, flow-optimized designs, e.g. double butterfly valves, are advantageous.
• Flap check valves should be low-maintenance and have a long service life.
• Check the availability of spare parts such as seals or springs.
• For critical processes, a valve with low-wear bearings or self-cleaning seats is worthwhile.
• Good documentation and easy disassembly save time and money when servicing is required.
• Choose materials suitable for the medium and environment: gray cast iron, cast steel, stainless steel, bronze, plastics.
• Check whether the manufacturer offers quality certificates, e.g. ISO 9001, or special approvals such as DVGW, WRAS, FDA, ATEX.
• Hygienic standards and approvals are essential for drinking water and food applications.
• An experienced manufacturer not only offers the product, but also advice and design assistance.
• The availability of 3D CAD data, assembly instructions and calculation tools facilitates integration.
• A global service network or fast delivery of spare parts can be crucial, especially for safety-critical systems.
• When purchasing, it's not just the purchase price that counts:
• Consider the total cost over the life cycle energy consumption due to pressure loss, maintenance, replacement.
• Higher-quality valves can quickly pay for themselves through a longer service life and lower energy consumption.

The professional purchase of flap check valves requires a holistic approach. The decisive factors are the medium, pressure, temperature, design, installation position and flow behavior. Equally important are quality, service and availability of spare parts. A carefully selected flap check valve reliably protects systems, reduces operating costs and extends the service life of the entire system. If you consider not only the price, but also operation and maintenance, you will ensure safety and efficiency for many years to come.

Flap check valves can be purchased from various suppliers. You will find comprehensive information on manufacturers and suppliers of Flap check valves around the world on Exportpages.