Dump valve

Dump Valve

A dump valve, also known as a blow-off valve (BOV), is a pressure release system present in most turbocharged engines. Its primary function is to release air pressure from the turbocharger when the throttle is closed.

Function

The dump valve operates when the throttle plate is closed, and the engine is still spinning, creating a high-pressure area ahead of the throttle plate. This pressure needs to be released to prevent damage to the turbocharger. The dump valve accomplishes this by opening a valve, allowing the pressurized air to escape, usually to the car's intake system or the atmosphere.

Types of Dump Valves

There are two main types of dump valves: atmospheric and recirculating.

Atmospheric dump valves vent the excess boost pressure into the atmosphere. They are known for the distinctive "whoosh" sound they make when the throttle is lifted.

Recirculating dump valves redirect the excess boost pressure back into the intake stream before the turbocharger. This type of valve is quieter and is often used in factory turbocharged vehicles to comply with noise regulations.

Importance

The use of a dump valve in a turbocharged engine is crucial for its longevity. Without a dump valve, the sudden pressure increase caused by the closing of the throttle can cause damage to the turbocharger and other components of the engine. This phenomenon is known as compressor surge.

See Also

• Turbocharger
• Compressor surge
• Throttle