Häger GmbH & Co. KG DIN check valves
The check valves (swing check) operate almost autonomously within the pipeline. Due to their design, the flow of the medium can only occur in one direction. Backflow of the fluid is not possible because the fluid pressure pushes the valve into its seat. This also ensures a high level of tightness.
The key characteristics of check valves
Check valves reliably prevent backflow of fluids and are available in nominal sizes ranging from DN 40 to DN 1200. They can be installed horizontally or vertically (with the flow direction upward). Depending on the requirements, they are available with a lever and weight for quick closing, or with a hydraulic damping system for smooth closing, as well as optionally with a heavy-duty hook for large nominal sizes.
Design and function of check valves
Check valves consist of a body with a shaft that holds the valve disc. The disc is mounted eccentrically on the lever and is lifted by the flow of the medium, opening the flow passage between 50 and 90 degrees.
The closing element is influenced by the weight of the valve disc, shaft friction, and buoyancy. However, check valves often close quickly and abruptly, which can cause a sudden movement as the valve nears closure.
Closing behavior of check valves
The closing behavior of check valves can be problematic because, as the valve disc begins to close, its surface area increases, leading to a sudden and hard shut-off.
Unlike a gate valve, which is directly affected by backflow, this delay can cause an aggressive final seating of the valve.
Extension options for smoother closing
To achieve a smoother closing, check valves can be equipped with a lever and counterweight. These components help slow down the closing process and minimize the impact of sudden shut-off.
Additionally, hydraulic damping systems can be integrated to further control the closing speed. Contact us for a customized solution.
Häger Check Valves
Datasheets
DN: 40–900
PN: 16, 25, 40, 64, 100
Body Materials: 1.0619, A216 WCB, 1.4408, 1.4306, 1.4404, 1.1138, 1.4308, 1.5419, 1.7357, 1.7379, CF8M, CF3M, CF3, WC1, WC6, WC9, LCB, LCC
Description of Our Check Valves
- Face-to-face length according to DIN EN 558-1
- Ideal for preventing backflow in piping systems
- Operates independently – opens automatically by fluid flow
- Optional design with lever and weight available
- Robust, heavy-duty construction with internal disc shaft
- Supplied with Declaration of Conformity and CE marking according to 2014/68/EU
- Available with flanged ends (EN 1092-1) or welding ends
- Bolted bonnet for easy maintenance access
- Disc available in various materials
- Depending on material selection, the check valves are suitable for water, steam, oil, gas, or other aggressive media
- Special coating available according to customer requirements
- Operating and maintenance manuals for the gate valves can be provided in various languages
- EAC TR-TS conformity declarations of the Customs Union available independently of orders for export and use of products in the Russian Federation, Belarus, or Kazakhstan (EAC), valid for 1, 3, or 5 years; EAC GOST TR TS 010/2011 (Machinery Directive) or EAC GOST TR TS 032/2013 for valves ≥ DN25
- Valve passport TP according to GOST 2.601 – 2006
- TÜV inspections (3.2)
Additional Information on Check Valves
Here you will find more information about our services, as well as key details to support your decision-making process for selecting your new industrial valve.
connection options
These check valves are primarily supplied with flanges according to DIN or ANSI standards. The face-to-face length is designed so that the disc does not extend into the downstream pipeline when in the open position. The same applies when welding ends are used instead of flanged connections. For larger nominal diameters, X-ray inspections of the welded connections are performed to ensure that any cracks at the machined ends are immediately detected.
Criteria for closing the flap
With check valves, the closing process must be completed before backflow occurs. This is the primary function of this type of valve. As a result, the closing time is relatively short. The goal is to prevent a pressure buildup in the pipeline that exceeds the system pressure. Additionally, the short closing time of the valve can cause a pressure surge or water hammer. This effect is generally undesirable and, under certain conditions, may cause damage.
Industrial check valves
Check valves are available in nominal sizes ranging from DN 40 to DN 1200. They can be installed in a pipeline either horizontally or vertically, but only with the flow direction upwards. Upon request, the valves can be equipped with a lever and weight. The lever and weight are especially beneficial when backflow reaches the valve before the disc has closed. The weight causes the valve to close with a snap. If a soft closing is desired, we recommend the version with a hydraulic damping system. The closing speed can be adjusted depending on operating conditions. For optimal and easy installation, larger nominal sizes can be equipped with a heavy-duty hook upon customer request.
flap beat
A too rapid closing of the valve can cause what is known as valve slam. For nominal sizes from DN 400 and above, we therefore recommend using a lever and counterweight. The closing time—and consequently the severity of the valve’s impact on the seat—is influenced by the reversal time of the flow, the density of the medium, and the inertia of the valve. When used in steam or gas systems, the installation of a lever and counterweight is advisable.
Design and function
Check valves and swing check valves belong to the group of backflow preventers. The swing check valve consists of a body with an upper-mounted shaft and a straightened seat ring. The body is closed with a cover, which can be easily removed for maintenance purposes. A movable shaft inside the body is connected to the disc. The shut-off element is the disc, which is flexibly mounted eccentrically on a lever. During flow, the disc is lifted by the medium, opening a flow cross-section of approximately 50 to 90 degrees, depending on the type.
The weight of the disc combined with shaft friction and buoyancy determines the tendency to close. It is important to note that the weight of the disc does not increase linearly with the nominal size. However, swing check valves have the disadvantage of potentially closing very hard. Unlike a gate valve, where the wedge is immediately subjected to full backflow pressure, the nearly horizontal disc behaves differently. As the closing process begins, the projected area increases and reaches 100% just before the end position. This causes the opposite of what is ideally desired: a slow closing initially, followed by a sudden rapid completion of the final closing angle.
