What Is a Poppet Valve?

A poppet valve is a mechanism that regulates the flow of fluid by a unique design consisting of a seat-like element, which opens and closes as the flow requires. Used for a wide variety of applications, poppet valves are most notably utilized in internal combustion engines. The poppet valve has a distinctive shape that resembles a mushroom, which rises or falls in a straight line from its seat.

The origin of the term "poppet valve" has its roots in medieval English. "Poppet" means "doll," which is similar in meaning to the words "puppet" or "marionette." The valve operates on the same basic principle as a puppet, moving in response to a remote motion conveyed in a nonstop manner.

The design of the valve is unique among the wide variety of valves on the market. The poppet itself is a movable device within the valve that regulates and directs the flow of fluid through the body of the valve. There are two types of poppet valves: a two-way normally closed valve and a two-way normally open valve. In the first, a stem impels the poppet from its seat to open up the amount of allowable flow. In the latter, a stem constricts the course of flow by pushing the poppet back into its seat.

The stem of the valve is powered by one of any number of instigators, which vary with different types of poppet valves. Some are automatic, while others require manual activation. Certain types of valves involve the use of a piston chamber, which applies pressure to the stem, in turn applying pressure to the poppet. Still other designs utilize a solenoid coil — known as a poppet solenoid valve — which employs a tightly-wound spiral to exert force onto the stem.

Poppet valves are used by numerous industries for regulating the flow of liquids and gases. When working with semiconductors, experts utilize an air poppet valve to isolate sanitary air flow. A poppet check valve, which offers a tight seal in low-pressure environments, is commonly used in water treatment and the manufacturing of car wash and laundry equipment. In the dairy industry, a hydraulic poppet valve ensures milks flows unabated through the necessary mechanisms and containers.

The vast majority of piston engines utilize poppet valves. The engine applies pressure to the valve through the use of cams, which are connected to the camshaft. The camshaft, in turn, is joined to the crankshaft, which operates at half its full speed in a normal four-stroke engine. A four-stroke engine is the typical internal combustion engine used in most cars and trucks.