Needle valves are valve designs that are constructed with a small opening accompanied by a plunger that looks a great deal like a common sewing needle. The purpose of this type of valve is to create a means of controlling the flow of liquids or gases through the valve mechanism. It is possible to easily adjust the flow rate to any specific amount desired, making the needle valve useful in a number of applications, including engines.
Like all industrial valves, needle valves are used to control flow. They are similar in construction to globe valves, but are most often used for the precision regulation of relatively low flow rates. Many needles valves tend to be smaller in size for the finest flow control. They are widely used for instrumentation control, line shut-off, and pressure regulating for a wide variety of applications.