Needle Valve:

Needle valves are used for precise regulations of liquids or gases in a piping system by moving the tip on the valve stem (the needle) into and out of the flow. Both the shape of the stem tip and the fine threads on the valve stem help the needle to be placed at precise points between fully open and fully closed. A needle valve's material type determines its usage—for example, metal valves are suitable for high pressure environments, while composite valves can be used in light weight applications The bonnet on needle valves can be integral (forged or milled as part of the valve body for strength), threaded (for durable pressure-tight seals where removal or replacement is not needed), or union (fits over the valve stem and held in place with a ring nut for repeated removal and replacement). Hand wheels, lever, and T-bar handles are made from various composites and materials that can be color coded for quick identification. These valves are used as either stand-alone valves or as flow control valves for gauges or instruments that could be damaged by flow and pressure fluctuations. Needle valves are suitable for use in fine adjustment and regulated flow applications in industries such as gas, chemical, hot water heating, and in scientific labs and textile manufacturing.

Compression Fitting:

The compression fitting is composed of an outer compression nut and an inner compression ring or ferrule (sometimes referred to as an "olive"). Ferrules vary in shape and material but are most commonly in the shape of a ring with beveled edges. To work properly, the ferrule must be oriented correctly?usually the ferrule is fitted such that the longest sloping face of the ferrule faces away from the nut. When the nut is tightened, the ferrule is compressed between the nut and the receiving fitting; the ends of the ferrule are clamped around the pipe, and the middle of the ferrule bows away from the pipe, making the ferrule effectively thicker. The result is that the ferrule seals the space between the pipe, nut, and receiving fitting, thereby forming a tight joint.