Double offset design for high temperature, pressure services
Single eccentric disc contacts the seat more than necessary in the process of closing. This added friction increases torque, and consequently increases wear to shorten the life of the valve.
Double Eccentric Disc
In the Tomoe double eccentric design, the disc rotates freely, not contacting the seat until final closing; then the whole face seats simultaneously for positive shut off with low torque. At the same time, reduced friction extends the life of the metal seat.
Spherical Disc Design
This high-precision machining technique lowers torque and provides a perfect seal. The spherical disc dramatically reduces friction, prevents wear and extends valve life.
Coil spring insert for improved elasticity
The basic metal plate-loaded design is easily deformed and will not provide complete shut-off. The Tomoe design using coil spring inserts increases the elasticity of the metal seat. This allows the seat to deform with seating torque or disc distortion, and still return to the required tolerance (shape) once the stress is removed. Each coil turn works independently to maintain the shape of the area of the seat it contacts.
Sleeved insert for stress distribution
To prevent indentations that may leak under high pressure, the coil spring is placed within a metal sleeve, to distribute the stress of the inserted spring. This spring, supported on three sides, has little expansion space. When the disc diameter expands with temperature,the operating torque increases drastically. The spring design compensates for the Disc expansion enabling lower and more consistent torque figures to be achieved.