What Is a Needle Valve

Needle valve is a small device that is used to control the flow of fluids. A pin-based mechanism is used to control the flow. The mechanism provides for an easy control of flow making it a popular device. The flow rate can be adjusted as required. The device finds application in numerous uses especially in different types of engines.

A needle valve features a tapered plunger and a screw like seat for holding the plunger. The seat helps to rotate the plunger that can then be used as a valve. A high degree of precision control can be obtained depending upon how the rotations are coupled with the degree of valve-turn. A high degree of precision can be obtained by tuning the rotations so that they result in less degree of turn.

The high degree of control over the flow that a needle valve provides makes its ideal to be used as a valve in cases where flow needs to be regulated to a higher precision. Brass and stainless steel needle valves are often used in billing meters since they are less prone to temperature variations and weather elements. The meters include natural gas, water, and power meters. Power and chemical plants also use needle valves to control the flow of fluids to other subsystems. These valves help to control the flow as well as act as safety devices that can be used to completely shut down the flow if required. 

Common usage of needle valve is in car carburetors where it regulates the flow of gas to the engines. An excess gas may choke the engine’s carburetor leading to engine shut off whereas insufficient amount can result in excessive wear and tear of the engine. Float valve is often used in place of needle valve but it also based on the same underlying principle that needle valve is based on.

Another common use of needle valve is in water heating equipments that are used for home purpose. In residential water heaters, the valve is used as a bleed valve to control the pressure generated by the heated water thus aiding its flow. The valve also regulates the flow of liquid through the heater thus making sure that the temperature of the water is maintained for a long time.

As compared to other devices, a needle valve fairs fairly well due to its inherent design. However, it has one limitation. It is not possible to determine the position of the valve thus making it difficult to judge whether a valve is open or closed. The limitation can however be overcome by using a needle valve together with other equipments.