| 摘要 |
<p>A non-return valve in the air inlet of a pulsating burner includes a flat circular ring of elastic material such as steel or plastics. The outer edge of the ring is provided between annular abutment surfaces with a predetermined play. The inner edge of the ring is movable from a closed position to a fully open position where it has the shape of a truncated cone. The angle between the conical surface of the frustrum and its base is small in the fully open position, in the order of magnitude 3.degree., and resistance to opening is extremely small to permit rapid changes between open and closed positions.</p> |
