What is a characteristic feature of a poppet valve?

A poppet valve is characterized by its use of a spring mechanism to operate the valve opening and closing functions. The spring serves to push the poppet (the sealing element) against the valve seat, ensuring a tight seal when the valve is closed. This spring-loaded design allows for the valve to respond to pressure changes, quickly opening to allow fluid flow and closing to prevent backflow.

The flexibility in operation provided by the spring is crucial for applications where precise control of fluid flow is necessary. Additionally, while poppet valves may be found in various systems, they are not limited to operating only under vacuum pressure or without guides for closure. These features differentiate poppet valves from other types of valves that may rely on different operational principles.