n. device or structure for controlling the flow of a fluid
They're done to improve the health and vigor of people with heart valve diseases.
Sentence in Classic:
Only now did Pierre realize the full strength of life in man and the saving power he has of transferring his attention from one thing to another, which is like the safety valve of a boiler that allows superfluous steam to blow off when the pressure exceeds a certain limit.
War and Peace(V5) By Leo Tolstoy Context
Whenever I see the movement of a locomotive I hear the whistle and see the valves opening and wheels turning; but I have no right to conclude that the whistling and the turning of wheels are the cause of the movement of the engine.
War and Peace(V4) By Leo Tolstoy Context