Check valves; These are the safety armatures produced to prevent the flowing fluid from returning back. There are different types that can be used for all kinds of fluids.

a) Check valve types:
– Lift check valves: The closing element moves in the direction perpendicular to the seating surface. There are spring and non-spring types. In both types, the throttle is opened by the fluid pressure, in the non-spring types, the throttle is closed, and in the spring-loaded types, they are closed with the force of the spring. Springless types only; they can be mounted vertically, with the flap above the seating surface. Spring types, on the other hand, can in principle be mounted horizontally or vertically. They are produced in small nominal sizes (up to DN 300). They are manufactured using seated type (Glob) valve bodies, as well as axial-flat body types. Screwed, flanged, compression type connections are in question.
Advantages: The throttle stroke is shorter than other types. So they can close more quickly. Complete sealing can be achieved. All parts can be selected from special metals and high temperatures and nominal pressures can be reached.
Disadvantages: Resistance factors are higher than other types.
– Swing check valves : The closing element oscillates around a hinge system axis that remains above the seating surface. They can be mounted horizontally and vertically, provided that the flap hinge axis stays above the seating surface. In order to prevent their sudden shutdown; There are arm types that can be applied weight, spring, shock absorber. They are produced up to DN 1000. Nominal pressure ≤ PN 16. Screwed, flanged, compression type connections are available.
Advantages: Since the passage is fully open in the open position of the damper, the resistance factors are low.
Disadvantages: Difficult to achieve full sealing.
– Tilting check valves (Tilting check valves- Kipprückschlagklappen): The closing element oscillates in a hinge system axis like swing check valves, but the hinge system is slightly above the seat surface axis. They are produced from DN 150 to DN 2000. Nominal pressure ≤ PN 16.
– Membrane check valves (Diaphragm check valves: When the fluid enters the membrane in the form of a tube with its mouth closed in the flow direction, the mouth opens and flow is provided thanks to the stretching ability of the membrane. In the opposite direction, the fluid remains in the closed mouth before it has a chance to enter the membrane and cannot return. These types of check valves are mostly used in waste water lines containing solid parts.

Matters to be considered in the business:

The most important issue in check valves is to ensure that the flap moves smoothly and without snagging. Sediment accumulating and jamming in the flap seat in the hinge system or in the lift valves over time, etc. substances may hinder the movement of the damper. Using a strainer and cleaning at regular intervals will ensure trouble-free operation.