A pioneering and innovative departure from the traditional hard seat approach to achieving valve sealing efficiency and acceptable valve seat life.
Particle entrapment prevents seat erosion, removing the cause of valve wear.

Principle of Operation

The dome component closes beneath the seat (seal) when the seal is relaxed (not inflated), allowing a controlled gap between the seat (seal) and the dome component. Material is allowed to pass through or enter the controlled gap if, due to its characteristics, it is pulled into the gap by the action of the dome component moving to the closed position.

In the closed position, high-pressure air or other gas enters the space between the back of the seal face and the profile ring to cause the seal face to expand onto and around the periphery of the dome component. Material particles are entrapped by the seal against the dome surface, irrespective or particle size or shape. Before opening the valve, the seat is relaxed, and the controlled gap is re-established before the dome component moves to the open position.

The seal is a loose component clamped into place by a keeper ring and external fasteners holding the top plate assembly to the body. The seal is easily removed for inspection.

U.S. Patent No. 4,137,935

Inflatable Seats Inflatable flexible seats entrap particles that are normally the cause of seat erosion. Particles are induced to move across valve seats under the influence of pressure differentials on either side of the closing member. Entrapping particles within a flexible face during the period of valve closure prevents particle movement and considerably reduces valve seat wear. Inflatable seats also allow automatic wear compensation.

Hard Seats The conventional hard material approach to valve seat life relies on crushing particles between the faces. This approach does not attempt to entrap particles, but causes the particles remaining to become very small to reduce their erosion effect on the valve seat. However small the particles are, each particle contributes to continuing erosion. Particle movement and initial erosion allows accelerated subsequent erosion since the hard seats cannot compensate for wear.