Abstract: A snap-action permanently indicating pressure relief valve is disclosed. The valve includes a valve member defining a flow path having an area less than the area of an inlet wherein the inlet pressure initially acts over a portion of a pressure surface of the valve member equal to the inlet area and subsequently acts over the entire area of the pressure surface to suddenly increase the velocity of the valve member. The valve member smacks and permanently deforms a deformable over pressure indicating element to give permanent indication of an over pressure condition.

Abstract: A vacuum venturi device including a bypass valve responsive to an increase in inlet pressure to divert pressurized gas to the low pressure port of the device to effect fast vacuum cut off and blow off.

Abstract: A bellows type vacuum cup including an annular volume over the bellows when completely collapsed exposing the entire inner surface of the cup to a vacuum source providing for increased workpiece holding force. Means for stabilizing the bellows against radial collapse is provided as well as means for reducing slipping of the cup on the workpiece surface.