What is a needle valve?
Needle valve is a valve design with a small opening and a plunger that looks like an ordinary sewing needle. The purpose of this valve is to create a device to control the flow of liquid or gas through the valve mechanism. The flow rate can be easily adjusted to any specific amount required, making needle valves useful in many applications, including engines.
The needle valve not only has a slender conical piston, but also has screws that can be installed in the so-called valve seat. The seat is positioned so that the screw can be rotated and the flow through the valve can be increased or decreased. Because of the structure of the device, it needs to rotate many turns to move the plunger, so the flow can be adjusted very accurately.
It is this ability to accurately control the flow that makes the needle valve flow very suitable for situations where the required flow must be maintained with little change.
The needle valve is a fine-tuning valve, and its valve plug is needle shaped, which is mainly used to adjust the throttle flow. The fine-tuning valve requires that the opening of the valve port gradually becomes larger, and the maximum continuous fine adjustment can be made from closing to opening. Needle valve plug can achieve this function. Needle valve plug is generally made of quenched steel long needle, while the valve seat is made of soft materials such as tin and copper. The sealing between the valve needle and the valve seat is achieved by the close fit of its conical surface. The taper of the valve needle is 1:50 and 60 cone angles, and the cone surface shall be finely ground. The sealing between valve stem and valve seat is realized by bellows. A common use of stainless steel needle valve and brass needle valve is in public instruments. In this case, it is necessary to accurately measure the electricity, water or natural gas consumed by customers during a given billing period. At the plant level, this type of valve is usually used to regulate the flow into the system, which is used to transport products to various destinations. By controlling the needle valve rate, the pressure on the conveying system can be kept to a minimum, which helps to improve the safety of personnel working in various positions of the system.
For engines that typically include carburetors, needle valves are usually devices that help regulate the flow of fuel into the device. This is very important because excessive fuel will block the carburetor and shut down the engine. At the same time, the lack of sufficient fuel flowing into the carburetor will cause additional wear and pressure on the engine over time, which may lead to high maintenance costs. An alternative to using needle valves is to include so-called float valves. In some cases, although the design is different, this type of valve is also recognized as a needle valve.
Needle valves are sometimes used in equipment that controls the water temperature in a particular system. For example, some residential water heaters use this type of valve as a discharge valve, which can reduce the pressure of water flowing through the equipment. Like other applications, the valve controls the flow of water through the heater, which is also a factor that helps minimize the energy required to maintain a fair hot water supply.
Although the use of needle valves has many advantages, the basic design does include a disadvantage. Unlike other types of valves, it is not possible to determine whether the valve is open or closed by visually observing the position of the screw or the handle used to control the position of the screw. Therefore, other equipment is usually included in the equipment design, so that the flow can be monitored and adjusted accordingly with valves.
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