1. What is a check valve?
Unlike the gate valve or butterfly valve, the check valve is a one-way valve that allows the flow of fluids in only one direction. For this reason, the check valve is also called a non-return valve. Mainly there are two parts: the input side and the output side.
Unlike the other valves that depend on a handle or actuator to work, the check valve relies on a pressure differential between two sides to work: when the pressure on the input side is higher than the pressure on the output side, the valve will open; otherwise, the valve will close.
The main purpose of the check valve is to prevent backflow in the system for the reverse flow can result in water hammer, which causes repeated extreme surges in the pipework, valves and fatally damages or ruptures the system and its pipework.
2. What is the difference between the check valve and globe valve?
Many people might confuse the check valve with the globe valve. The main differences between these two types are the following:
In terms of flow control, the non-return valve controls the direction of the flow while the globe valve is used to start, stop and regulate the fluid flow in pipelines.
As we mentioned before, the globe valve still requires human control by handle or actuator; on the other hand, the control of the check valve totally relies on the pressure differential.
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3. Types of check valve
There are many types of check valves, the main types are the following:
Swing check valve
Inside the swing check valve, there’s a disc seated over the inlet. When fluid goes in and applies pressure on the disc, the disc is pushed into the open position. When the pressure reduces or backward pressure occurs, the disc will be pushed back to the closed position.
Lift Check Valve
The inside structure of the lift check valve is similar to a globe valve. However, the disc is lifted and lowered by the fluid pressure instead of the actuator: when the flow is strong on the inlet, the fluid pressure lifts the disk off the seat and the valve is open; when the flow weakens or even stops, the gravity forces the disk down onto the seat.
Ball Check Valve
The working principle is similar to the lift check valve: inside the valve, there’s a spherical floating ball. When the flow is strong, the forward movement of the fluid moves the ball into the open position; when there’s backflow, the liquid moves the ball to return to the seat and seal the valve.
Dual Disc Check Valve
The dual disc check valve is also known as dual disc check valve or double disc check valve. There are two halves of the disc in the valve: while there’s a forward flow of the fluid, the halves are folded toward the centerline; while there’s reverse flow, the halves are open to seal the pipe.
The swing check valve and the dual disc check valve are our main products. As an experienced valve manufacturer and supplier, we produce check valves of high quality.
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4. What is a check valve used for?
The check valve is widely used in many industrial processes, especially in wastewater, potable water, and irrigation applications. Besides it’s also widely used in mining projects, oil & gas transmission, even in food & beverage production or pharmaceutical production.