Läppäventtiileissä

Läppäventtiileissä, commonly referred to as butterfly valves in English, are a type of quarter-turn valve used to control or isolate flow. The name "läppäventtiili" derives from the Finnish word "läppä," meaning flap or disc, which is the essential component of the valve.

The core of a läppäventtiili is a disc, typically circular or sometimes elliptical, mounted on a rod that runs through the valve body. When the valve is fully open, the disc is rotated 90 degrees to be parallel with the flow, allowing minimal obstruction. When the valve is closed, the disc is rotated perpendicular to the flow, effectively blocking the passage. The degree of opening can be adjusted to regulate the flow rate, though they are often used more for on/off applications or throttling in less demanding scenarios.

Läppäventtiileissä are known for their simplicity, lightweight design, and relatively low cost, making them a popular choice in various industries. They are suitable for a wide range of fluids, including water, air, gases, and some slurries, as long as they do not contain abrasive solids that could damage the disc or seat. Their compact design also makes them advantageous where space is limited.

The sealing mechanism in a läppäventtiili typically involves a resilient seat, often made of rubber, PTFE, or other elastomers, pressed against the disc when the valve is closed. This creates a seal to prevent leakage. For higher pressure or temperature applications, metal-seated variants are available. Actuation can be manual via a lever or handwheel, or automated using electric, pneumatic, or hydraulic actuators.