Chell has created a range of precision needle valves capable of repeatably delivering precise flows. The valves range from 0-20sccm to 0-3slpm. All feature stainless steel construction with Perlast seals (other seal materials are available) and a variety of fitting/flange options. The Mechanism range of stainless steel needle valves, developed by Chell Instruments, provide the finest gas flow control over typical ranges of 0-20, 0-1000 & 0-3000 std.cm3min-1 air at 1bar differential pressure. Designed for use in pressure or vacuum applications, they are ideal for use in gas analysers, chromatographs and mass spectrometers in addition to any application where fine gas flow control is required. The valve’s opening characteristics are extremely smooth, preventing bursts of gas which would disturb delicate or Ultra-High Vacuum instrumentation. Construction is in Stainless Steel, with Perlast perfluoroelastomer body seals and a Fluorosint orifice seal, for the best corrosion resistance. Vacuum rated valves are leak tested on a helium mass spectrometer. Valves are available with 1/16in single ferrule or 1/8in, 1/4in or 6mm twin ferrule compression fittings and additionally, vacuum models may be selected with NW10KF fittings. VCR fittings are also available and custom fitting types (including all welded) can also be accommodated. The Mechanism Valve was developed specifically for mass spectrometry inlet service, probably the most critical application for such a valve but is eminently suitable for many other demanding applications where long-term stability is required