Needle valves are linear motion type valves used to make fine flow adjustments. Needle valves are normally hand operated although it is possible for other actuators to be used.
The needle valve obtains its name from the long needle like shape of the disc. The needle is long and thin with a gradually increasing diameter towards the stem. When closing, the tip of the needle passes through the seating orifice and the needle continues to pass through the orifice until the needle diameter is the same size as the orifice diameter; the valve is closed when this occurs. Due to the needle shape, flow gradually increases as the valve is opened.
When fine flow adjustments are required, the needle valve is preferred over all other valve designs because each rotation of the actuator wheel is proportional to the flow amount. Metering gauges are almost always of the needle valve design.
3D Model Components
This 3D model contains all common parts of a needle valve, these include:
How Needle Valve Work
The below video is an extract from our Introduction to Valves Online Video Course.