Knowledge of Needle valve
What is a Needle valve?
Needle valve is a globe valve with a conical plug (needle) closing into a small seat. Used for flow metering and damping pressure fluctuations on instruments such as pressure gauges… Instrument isolating valves are often called needle valves.
Needle valves are similar to globe valves. They’re used to start, stop, and regulate the flow rate within a pipeline.
However, needle valves are designed differently. Unlike globe valves, which have a disc, needle valves have a long, tapered, needle-like point at the end of the valve stem. This is often referred to as the plunger.
These valves also have a handwheel or a small handle located on the plunger that controls the position of the plunger.
The valve’s needle-like plunger fits into the seat. Because of this unique design, a needle valve can precisely and accurately control how much fluid passes through the valve.
How Does a Needle Valve Work?
Needle valves can operate manually or automatically. Manually operated needle valves use the handwheel to control the distance between the plunger and the valve seat. When the handwheel is turned in one direction, the plunger is lifted to open the valve and allow fluid to pass through. When the handwheel is turned in the other direction, the plunger moves closer to the seat to decrease the flow rate or close the valve.How Does a Needle Valve Work
Automated needle valves are connected to a hydraulic motor or an air actuator that automatically opens and closes the valve. The motor or actuator will adjust the plunger’s position according to timers or external performance data gathered when monitoring the machinery.
Both manually operated and automated needle valves provide precise control of the flow rate. The handwheel is finely threaded, which means it takes multiple turns to adjust the position of the plunger. As a result, a needle valve can help you better regulate the flow rate of fluid in the system.
Uses of Needle Valves
Needle valves are commonly used to control flow and protect delicate gauges from damage caused by sudden pressure surges of liquids and gases. They’re ideal for systems using lighter and less viscous materials with low flow rates. Needle valves are usually used in low-pressure hydraulic systems, chemical processing, and other gas and liquid services.
These valves can also be applied to high-temperature and oxygen service based on their materials. Needle valves are usually made of stainless steel, bronze, brass, or metal alloys. It’s important to choose a needle valve made with the material that’s best suited for the service you need. This will help to preserve that valve’s service life and keep your systems running smoothly and safely.
How to distinguish needle valve from other valves?
There are different valves for different use. Knowing what valve is being used on a certain engine or things will enable you to maintain its functionality and performance. Different type of valves may include ball valves, check valves, butterfly valves and needle valves. Other valves are used generally for industrial purposes. Valves can be manual or automatic, too.
A needle valve is a type of valve that is designed to control the volume of liquid that flows in small lines. As the liquid that passes through the valve makes ninety degrees turn passing through an orifice that seats a rod with a cone-shaped tip, the size of the orifice changes depending on how much or how little liquid flow is required.
Unlike other valves, a needle valve has a slender, pointed tip that is used to control the flow of the liquid. It has a small orifice with long seat and a plunger that is shaped like a needle which fits the seat. The plunger will evidently retract when the screw is being turned slowly allowing the flow of gas and liquid at a precise amount required by the user. You will have to make many turns before a full flow is possible. As such, this type of valve shall not be used for simple shut-off operations. This type of valve is normally used for very low flow rate requirements at a very accurate regulation. Precise resistance is made possible by the fine thread on the stem and its large seat area. These valves are being used if the requirement is a controlled flow as it can be damaged by a sudden surges if put under a lot of pressure. It also allows sudden stop of liquid or gas flow if the situation requires. Any adjustment of flow is possible when one is using needle valves. But unlike other valves, you will not determine how loose or tight the flow is just by looking at it.
Generally, these valves are used in flow metering applications. Calibrated flows will require this valve having the capability of allowing low flow rate and maintained flow requirement. A very light twist will enable on and off function of the flow making it easy to use, too.
A needle valve is normally designed with the use of a metal needle and elastomeric seat. On the other hand, there are those that are designed using plastic as well. Metal needles may be brass or bronze, other form of steel is also available. Variation in the use of materials can be attributed to a specific function or requirement. There may be a need for a durable usage and some may require moderate function only.
Needle valves are used in many different applications. Generally, any metered flow of steam, air, oil, water, gas or any other form of liquid will require this type valve. This valve is used in many industrial need and even domestic, too.
Source: China Needle Valves Manufacturer – Yaang Pipe Industry Co., Limited (www.metallicsteel.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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