Fluid Controls Ltd is one of the UK’s leading distributors for pressure control

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Needle valve

What is a needle valve?

Needle Valves allow for precise regulation of flow, albeit generally at relatively low flow rates. In this article, Fluid Controls gives you an overview of the function, design and applications of a needle valve, and highlights some of our popular needle valves from Parker.

A typical Needle valve design features a tapered pin to gradually open a space for fine control of flow, which can be controlled and regulated with a spindle. A needle valve has a relatively small orifice with a long, tapered seat, and a needle-shaped plunger on the end of a screw, which fits the seat exactly.

As the screw is turned and the plunger retracted, flow between the seat and the plunger is possible. However, until the plunger is completely retracted, the fluid flow is significantly impeded. Since it takes many turns of the fine-threaded screw to retract the plunger, precise regulation of the flow rate is possible.

Needle valve applications

Needle valves are used to control flow in delicate gauges, which might be damaged by sudden surges of fluid under pressure. They are also used in situations where the flow must be gradually halted, and where precise adjustments of flow are necessary or where a small flow rate is desired.

Needle valves can also be used as on/off valves or for throttling service. They are also ideal in vacuum systems, when a precise control of gas flow is required, at low pressure, such as when filling gas-filled vacuum tubes, gas lasers and similar devices.

Parker needle valves

Parker’s PV Series of Rising Plug and Gauge/Root Valves are available with a variety of seat and seal materials. They are screwed bonnet designs featuring bonnet lock plates. These valves provide a straight through flow path in two orifice sizes, utilising a non-wetted upper stem and a non-rotating lower stem in conjunction with a tapered seat for positive shut-off and long seat life, even in particulated media.

Parker V Series Needle Valves are designed for positive leak tight shut-off and regulation of fluids in process, power, and instrumentation applications. With a wide variety of port sizes and styles, temperature capabilities ranging from -65 °F to 450 °F (-54 °C to 232 °C) and pressures to 5000 psig (345 bar), V Series Needle Valves provide the user with the utmost in flexibility when designing miniaturised tubing or piping systems.

Parker U Series Union Bonnet Valves have been engineered for use at pressures up to 6,000 (414 bar) and temperatures as high as 1,200 °F (649 °C). A non-rotating lower stem helps to extend packing life by removing rotation from the packing area. Stem packing below the threads isolates the thread lubricant from the flow, ensuring adequate lubrication regardless of the media.

Fluid Controls also supplies Parker’s VQ Series, NP6 Series, SN6 Series and HV (Hand Valve) Series needle valves.

Speak to a Fluid Controls adviser today about all your Needle Valve requirements by calling +44 (0) 118 970 2060 or email fluid@fluidcontrols.co.uk.

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