Yes, a butterfly valve can control flow and may remain partly open, but only when the valve, actuator and operating range have been selected for throttling service. A line-size on-off butterfly valve held near the closed position can suffer poor control, cavitation, noise, vibration and concentrated seat or disc erosion. Partial opening is not inherently harmful; operating at the wrong opening for...

A wafer ball valve usually fits a tight piping layout better because its body is shorter and lighter than a conventional flanged ball valve. This saves axial space, but the shorter valve may still be difficult to use if there is little room for through-bolts, flange separation, the handle or the actuator. Compare the complete installation and maintenance envelope, not face-to-face length alone. &n...