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 Does a Solenoid Work?
Ball Valve Torque Calculation
How to Install a Flow Control Valve
Difference Between Standard & Full Port Ball Valves
Difference Between Reciprocating & Centrifugal Pump
How to Fix a Submersible Water Pump
How to Figure GPM Water Flow on an Existing Chiller
What Are the Functions of the Left & Right Atria?
Differences Between a Ball Valve & a Butterfly Valve
What Is an Instrument Which Measures the Pressure of...
How to Convert CV to GPM
What Is an Open Diode?
How Do Electric Hot Water Heater Check Valves Work?
Chemoreceptors & Heart Rate
How to Perform a Fire Pump Churn Test
How to Hook Up a 480V, 208V, or 120V Transformer
Guide to Troubleshooting Photocell Sensors
How Do Pneumatic Controls Work?