How Does a Check Valve Work?

The cooling towers in a power plant contain check valves.
••• Digital Vision./Digital Vision/Getty Images

A check valve is among the simplest valves in the industrial world. Found in practically all systems, these valves allow unidirectional fluid flow through a pipe or aperture. They require no manual adjustments because they are flow-sensitive; they open in response to a certain "upstream" pressure level and close below it, or in response to positive "downstream" pressure. Sump pumps, steam lines, irrigation systems and injection lines all feature check valves, and the valves between the atria and ventricles of your heart are essentially check valves.

Types and Basic Design

Common check valves include the swing check valve, which operates much like any gate, and the ball check valve, in which flow stops in response to the occlusion of the opening by a spherical component. When fluid flow pressure becomes sufficiently great -- and the value of this pressure varies according to the design of the valve, which in turn depends on the needs of the system -- a disc within the valve housing slides forward, drawing the gate or ball open and allowing flow through the opening. The internal sealing of these valves is self-regulating, so minor levels of backflow often occur.

Related Articles

How Hydraulic Pilot Valves Work
How Do Electric Hot Water Heater Check Valves Work?
How Does a Solenoid Work?
How to Fix a Submersible Water Pump
What Is an Instrument Which Measures the Pressure of...
How a Solenoid Pump Works
Ball Valve Torque Calculation
What Is the Function of a Voltage Regulator?
How Do Pneumatic Controls Work?
Difference Between Standard & Full Port Ball Valves
What Is an Open Diode?
How Pneumatic Timers Work
Difference Between Reciprocating & Centrifugal Pump
Differences Between Rotary & Reciprocating Compressors
How to Hook Up a 480V, 208V, or 120V Transformer
What Is a Solenoid?
How to Install a Flow Control Valve
How to Calculate Heat Loss During Pipeline Depressurization