Gate valves are named after a wedge-shaped internal plastic barrier, called a gate which rises and falls inside the valve as a handle is turned (the handle does not rise or fall, only the gate). Gate valves effectively regulate flow rates from zero to full flow, they work well with solids-laden water, and these valves can be serviced in place if necessary. In comparison, ball valves are designed to be either fully on or fully off, and can be easily damaged by solids-laden water. Thus ball valves are usually not repairable unlike gate valves.