Fluid handling – With leakage or drip collecting
Patent
1998-06-11
2000-01-18
Bennett, Henry
Fluid handling
With leakage or drip collecting
137240, 13761418, F16K 1120, F16K 5100
Patent
active
060149833
DESCRIPTION:
BRIEF SUMMARY
A double seat valve with leakage protection, in particular for the food and beverage industry, which in its housing has two cooperating valve plates, which define a hollow leakage chamber that typically opens into the open air via lines, wherein for actuating both valve plates, one common drive is provided, which includes a cylinder with a first work piston, loaded on both sides by compression springs and being fixedly connected to the valve shaft of the lower valve plate, wherein this valve shaft passes in telescoping fashion through the upper valve plate and its tubular shaft, which in turn protrudes with its upper end into the cylinder and there carries an abutment for the lower compression spring that presses the upper valve plate into its seat, while the upper compression spring, which is braced by its upper end on the upper cylinder cap, presses the lower valve plate against its valve seat, and a second work piston, acting on the tubular shaft, is disposed in the cylinder below the first work piston, and a third work piston which is movable on the tubular shaft is disposed between the first and second work pistons, wherein the third work piston is sealingly surrounded on its circumferential surface by the first work piston, and the first and third work pistons are embodied as displaceable relative to one another.
A stop valve of this same generic type is known from German Patent Disclosure DE 42 36 464 A1. The seat faces of the two valve plates are embodied conically and are oriented in such a way that the two valve plates move in the same direction into the seat face. Between the valve plates, a leakage chamber is formed, which via a line typically discharges into the open air. This reliably prevents any mixing of media. In the closed state, the upper valve plate is pressed by the pressure of the medium more firmly into its valve seat, while the lower valve plate is relieved. To prevent pressure surges from raising the lower valve plate and allowing medium to pass into the leakage chamber, the lower valve plate is extended downward in the form of a compensation piston, which has approximately the same diameter as the lower valve plate. Pressure surges in the pipeline thus act with the same force on the compensation cylinder and on the valve plate, so that the pressure forces in the axial direction compensate for one another.
The valve can perform three functions. For opening the valve, the two valve plates are raised; for cleaning the valve seats, the lower and upper valve plates can each be raised slightly, individually. To that end, the valve is equipped with a cylinder, which has four pistons. The work pistons act on the two valve plates via two concentrically disposed valve shafts. For opening, a first work piston is raised by compressed air until it strikes a second piston, which is connected via its valve shaft to the lower valve plate. The first and second pistons are raised farther, carrying the lower valve plate along with them, until the lower valve plate strikes the upper valve plate. The leakage chamber is now closed. On being raised further, the two valve plates move together upward, thereby opening the valve. The closure of the valve proceeds in the reverse order of work steps. For cleaning the valve seats, the valve plates must be raised individually. To that end, a third and fourth piston are provided, which act on the lower and upper valve plate, respectively, via their valve shafts. The third piston is located between the second piston and the lower housing wall of the cylinder. If it is acted upon by compressed air on its underside, it is raised slightly, until it strikes against an abutment. Via the associated valve shaft, the upper valve plate is raised somewhat from its seat. The medium can pass through an annular gap between the valve plate and the valve seat into the leakage chamber. This increases the pressure on the lower valve plate, thus pressing it more firmly into its seat.
For cleaning the upper valve seat, the fourth piston, which is located between the first piston a
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Lindholm Jensen Karl-Age
Schneiderreit Per
Sondergaard Bjarne
Alfa Laval LKM A/S
Bennett Henry
Kim Joanne Y.
Striker Michael J.
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