Instrumentation needle valves – general information
Needle valves (depending on the type of valve and stem applied) are used to control flow rates, to open or close the flow completely and for metering media. As opposed to ball valves, the needle valve is opened and closed by turning a knob many times. The process is gradual, no sudden rise or drop of pressure occurs, which is critical especially for high pressure gas applications and high flow velocity. The needle valves, with a special regulating stem in particular, can be used to control the flow rate in a system.
When an application requires highly accurate dosing of a medium, then metering needle valves are used. In this type of valves the medium flows through a calibrated hole in the seat of the valve. A tapered needle is in that seat. Movement of the needle closes or opens the flow allowing precise dosing of the medium by simple adjustment with the knob.
The construction of precision needle valves is tested for performance at burst pressure and at test pressure; stem is blow-out proof; all parts are manufactured from certified materials and precisely finished. Every ball valve is tested with nitrogen at 1000 psi (69 bar) for leaks in the body and seals to ensure leak-tight shut-off and longest service life. The valves are made of corrosion-resistant materials, whereas the right sealing material can be chosen from many options so as to match any medium, pressure or temperature. Come with several different connections: threaded, weld-in and double ferrule connectors (LET-LOK®).
Due to their outstanding reliability, the instrumentation needle valves are widely used in control and measuring equipment for the chemical, petrochemical, pharmaceutical and power industries, nuclear power plants and process engineering.