Valve for controlling fluid flow, especially of liquid plastics, in mixing heads

摘要

A valve, especially for controlling flow of single or multi-component plastic mixtures, has a housing(18) with a metering valve(15) whose outlet nozzle is opened or closed by a needle valve(23). Constant pressure is maintained in the fluid irrespective of whether the needle valve(23) is open or closed by a pneumatically loaded membrane(40) which acts on the needle valve.