Needle Valves 101:
A needle valve is a valve with a small opening, or port, with a needle shaped plunger that allows a precise regulation of flow.
A tapered pin is used in needle valves to gradually open a space. This can be regulated by using a spindle. It allows for fine control of flow. Generally, needle valves have small orifices and long, tapered seats. A needle shaped plunger fits on the seat at the end of a screw.
Needle valves are generally used in situations that call for a constant, calibrated low flow rate that must be maintained for a period of time. Needle valves are ideal for many different industries To name a few, they are used for plumbing, automotive, and chemical engineering fields. They are used when the situation calls for a constant, calibrated low flow rate. A carburetor is a perfect example. Because of their low flow rate, needle valves aren't used for shut off applications. (In that situation, a shut off valve would be used instead.) Small and simple needle valves work exceptionally well for hot water heating applications. They come in a variety of metals, such as stainless steel, carbon steel, andbrass.