This design offers the same mechanically assured shutoff as an RSBV, with zero leakage bidirectional shutoff and low-wear eccentric motion, but has further advantages, as I explain: The double eccentric C-Knife Gate Valve has a much simpler and more rugged design than an RSBV. It also has no stem wear, and it utilizes true rotary motion to greatly minimize emissions. With the same face-to-face and flow coefficients as an RSBV, a double eccentric C-ball valve is a drop-in replacement.