Spjäll

Spjäll is a movable plate or blade used to regulate the cross-section of a channel through which air, gas, or liquid flows. Typically mounted on a shaft with hinges or guides, it can be rotated (as a damper), slid, or lifted to adjust flow or to shut off passage entirely. Spjäll are made from metal or other materials suitable for the operating temperature and environment; in high-temperature applications, ceramic options may be used.

In ventilation and heating systems, spjälls are common as dampers in flue stacks, exhaust ducts, and air intakes to control draft, balance airflow, or isolate parts of a system for safety or maintenance. In fireplaces and wood-burning stoves, a damper in the chimney (spjäll) modulates combustion efficiency and smoke evacuation. In industrial processes, spjäll regulate gas throughput, pressure, and temperature, and can be arranged as parallel or concentric blade dampers for versatile control.

In automotive engineering, the term spjäll also refers to the throttle plate (in the throttle body or carburetor), which opens in response to driver input to regulate the amount of air entering the engine. Actuation can be manual (levers, wheels) or automatic, using electric motors, pneumatics, or hydraulics, often integrated with control systems or sensors.

Proper sealing, maintenance, and correct sizing are important to prevent leaks, ensure reliable shutoff, and achieve desired performance in the respective application.