Needle Valve
A needle valve is used to accurately control flow rates of clean gasses or fluids. The adjustments are gradual and smooth for controlling the flow rate, however, they can also be used as a reliable shut-off valve. However, they are generally only used for low flow rates and have a relatively large pressure drop from the inlet to the outlet. Common port sizes for needle valves range from 1/8” up to 2”. The most common application is to control the flow of a gas, like a propane needle valve does. Figure 1 shows an example of a needle valve.
Different Type of Needle Valve
A manually operated threaded needle valve (described above) is the most common type of needle valve. However, two additional variants are: motorized and angle.
-Motorized Needle Valve:These needle valves don’t have a handle for manual operation, but instead use an electric or pneumatic actuator to connect to and turn the plunger. These can be remotely controlled, used in a closed loop system, and/or put on a timer to accurately control the flow rate remotely.
-Angle Needle Valve:These needle valves turn the output from the inlet by 90 degrees instead of in-line. The same operation concept applies, but the 90-degree angle can allow for better system integration. Figure 3 shows an example of an angle needle valve.