For the GWC Valves International company, they carry many different types of valves along with different materials used to make them and one of their most commonly known valve is the needle valve. The needle valve is a type of valve that has a small port and a threaded needle-shaped plunger. How it works is it is able to allow precise regulation of flow and it is only capable of relatively low flow rates. When it comes to needle valves, they are usually used in flow-metering applications when they are constant and calibrated, and the low flow rate must be maintained for some time. The needle valves are commonly used to provide shut off for the pressure gauge and shut off of the supply used. Needle valves are not the type of valves you would use for simple shutoff applications. These types of valves can be easily damaged if they are turned off the flow with excessive force.
Depending on the valve, each valves is very different with the pressure and temperature along with how it can withstand different types of substances and materials. For the construction and the operation of the needle valve, it is very unique since there is a tapered pin to gradually open a space for fine control of flow for the instrument needle valve. Using a spindle, the flow can be controlled and regulated easily. How this works is when the screw gets turned and the plunger gets retracted, the flow between the seat and plunger occurs until the plunger gets completely retracted then the fluid flow is impeded. It takes very precise regulation for the flow rate to be possible when it comes to this needle valve. Needle valves are unique since they can also be used in vacuum systems since it requires precise control of gas flow and a low pressure.