How it works: suck-back to stop dripping and stringing

Suck-back retracts the needle slightly at closing so fluid at the nozzle tip is pulled back into the body, preventing dripping and stringing.

Three common mistakes: (1) assuming more suck-back is better — too much introduces air, (2) ignoring viscosity differences, since low-viscosity fluids need less, (3) tuning only the valve while ignoring supply pressure ripple.