Triple offset valves are set up much like double-offset valves, except that the profile of the Vacuum pumpsoutside diameter of the vane is machined as a conic section. The cone would be projected upstream, tilted along the edge of the pipe wall on the leading edge of the disc. The cone is not centered in the pipe-hence the third "offset". What this does is to allow seating without rubbing, and the seats hardly have to be resilient at all. SO once the valve is comanded to move, there is no breakaway torque, the running In-line pumpstorque is essentially just packing friction, and even the dynamic torque produced by the flowing media over the vane is low. I said the Magnetic pumpsseats are hardly resilient: Ususally the seats are something like a stack of thin stainless sheets bonded with graphite, so they can deform slightly and conform to the seating surfaces. Triple offset valves are Suber-water pumpsnot positon-seated-they are torque-seated. When the disc hits the seat it is metal-to-metal contact and they cannot be overstroked. But to get tight shutoff, it is necessaryScrew pumps for the actuator to lean on them mightily to squeeze the seating surfaces together. SO a triple offset can give you tight shutoff at elevated temperatures, there are no soft elastomers/polymers to be damaged by particles or velocity effects, and they work pretty well for control.

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