A flow control check valve regulates fluid flow in one direction while allowing free flow in the opposite direction. It combines the functionality of a check valve and a flow control valve.
Here's a breakdown of its operation:
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Flow Control in One Direction: A flow control element, often a needle valve, restricts the flow of fluid in one direction.
- As stated in the reference, a needle valve features a needle-like plunger that allows or restricts fluid flow by adjusting its position. When the needle valve is partially closed, the space through which the fluid travels is made smaller, which leads to a reduced flow rate.
- The amount of restriction, and therefore the flow rate, is adjustable.
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Free Flow in the Opposite Direction: In the opposite direction, a check valve mechanism allows unrestricted flow. This typically involves a poppet or ball that lifts off its seat when fluid pressure is applied, allowing free passage. When pressure equalizes or reverses, the poppet/ball reseats, preventing backflow.
| Feature | Flow Control Direction | Free Flow Direction |
|---|---|---|
| Mechanism | Needle Valve (adjustable restriction) | Check Valve (poppet/ball) |
| Functionality | Reduces the flow rate by constricting the fluid passage. The flow rate can be adjusted by changing the needle valve's position, controlling the opening size. | Allows unrestricted flow due to the check valve mechanism opening. Fluid can pass freely until pressure equalizes or reverses, at which point the valve closes. |
| Flow Rate | Variable, depending on the needle valve setting. | Maximum, limited only by the valve's physical dimensions and the fluid's properties (viscosity, pressure). |
In essence, a flow control check valve provides metered flow in one direction and unrestricted flow in the reverse direction, combining two distinct valve functions into a single component.
