Needle valve

Needle valve for controlling a fluid flow of a coating composition in a coating system, having

• a) a valve seat that tapers substantially conically in a direction of flow,
• b) a displaceable valve needle having a needle stem, a needle head, and a sealing element installed in the needle head of the valve needle to seal the valve seat in a closed position,
• b1) wherein the needle head closes the valve seat when the valve needle is in the closed position,
• b2) whereas the needle head frees the valve seat when the valve needle is in an open position,
• b3) wherein the needle head of the valve needle includes a conical lateral surface that tapers substantially conically in the direction of flow,
• b4) wherein the conical lateral surface of the needle head includes an annular groove in which the sealing element is installed,
• b5) wherein the conical lateral surface of the needle head forms an annular peripheral supporting surface upstream of the sealing element and rests with the supporting surface on the valve seat, and
• b6) wherein the needle head has in the supporting surface at least one flushing groove running axially which, when the valve needle is in the closed position, allows flushing medium to pass from the valve chamber to the sealing element, and
• c) a flexible membrane which surrounds the valve needle upstream of the needle head in an annular and sealing manner.