Needles are valves with a small port and a threaded needle piston. Allows fine adjustment of flow. However, it is generally limited to low flow rates. Manual or motorized needle valves are available. The distance between the piston and the seat of the electric needle valve is controlled by a handwheel on manual needle valves. The piston rises when the flywheel is turned in one direction. Opening the valve and letting the liquid pass. The electric hydraulic flow control valve is commonly used to measure flow rates. This is especially true in cases where a constant, calibrated low flow rate is required over a long period of time, such as idle fuel flow in the carburetor.
Describe the concept of a needle valve
Generally speaking, a needle valve is used to control the flow of gasses or liquids. To check the flow, The adjustment is gradual and smooth. However, it can also be used as a reliable shutoff electric needle valve. However, it is often used for low flow rates, and high pressure drops from inlet to outlet. Typical needle valve port diameters range from 1/8” to 2”. which is similar to the propane needle valve is to control the flow of gas.
The fine movement of the shaft allows the gearbox to move the piston tubes in a sliding direction to the open or closed position. according to the requirements of the control system
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Needle valve working principle
There is a manual and electric needle valve. On a hand operated needle valve, The handwheel controls the distance between the piston and the valve seat. The piston rises when the flywheel is turned in one direction. Opening the flow control needle valve and letting the liquid pass. The piston moves closer to the seat when the flywheel is turned in the opposite direction. Reduce flow or close valve.
The automatic needle valve has a hydraulic motor or air actuator that automatically opens and closes the electric needle valve. The piston position is adjusted by the motor or actuator in response to a timer or external performance data obtained during machine inspection.
Needle valves, both manual and automatic, Provide precise flow rate control because the wheel has a fine thread. As a result, needle valves can help you properly control the flow rate of fluid in your system.
The needle valve uses a tapered end that is raised and lowered by turning the handle to open and close the mouth. Next Image： Electric needle valve Cross-Sectional View, Layout, and Components The piston, also known as the rod (F), is attached to the handle (A). The piston moves up or down the thread as the handle (C) is turned. It cannot be unscrewed completely due to the lock nut (B). ).
While the piston is lowered, the tapered end (I) touches the proportional flow control valve seat. With the opening fully closed (H), the valve seat often narrows as well. Through port connection (G) on the inlet and outlet, You can connect pipes or hoses in a variety of sizes and configurations. The valve housing (E) is attached to the cap (D), which can be made of materials such as brass or stainless steel.
You can accurately position the tapered end of the piston from the flow adjustment valve seat by using threads to adjust the flow rate. As a result, you can control the flow between peak and zero simply by adjusting the position of the piston.
Uses of Needle Valves
Needle valves are often used to measure flow rates. This is especially true when the flow rate needs to be kept constant, calibrated, and low over time, such as idle fuel flow in the carburetor.
Note that the carb float valve (controls the fuel level inside the carb), not the electric needle valve. However, it is usually described as a single valve. Use a blunt, cone-shaped needle. But it sits with square-edged seats instead of matching cones. The intent is to provide a clear center between two narrow mating surfaces. This allows the current to close tight with only a small float voltage.
In general, an electric needle valve is also used to shut off the gauge or at the nozzle to shut off the NH3 supply to the blades in anhydrous ammonia (NH3) applications.
Due to the low flow rate AND the valve stem needs several turns to fully open or close. Therefore, needle valves are not used for simple closures. Due to the small inlet and fine thread rod strength advantage is high. Therefore, the electric needle valve is quite easy to close by applying “finger squeeze” pressure to the needle valve stem and/or seat. Especially brass valves. Easily damaged by excessive rotational force when power is cut off. The purge valves in hot water are often simple, small needle valves. Unlike ball valves or valves with raised stems, Checking the position of the handlebar is not easy to open or close the valve.
