Valco Instruments Co. Inc.Houston, TX
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 Valco injectors and valves for GC

For 30 years Valco valves have been the industry standard in gas chromatography. Models are available with 3, 4, 6, 8, 10, 12, or 14 ports, with 1/32", 1/16", 1/8", or 1/4" fittings, and with bore sizes from 0.25 mm (.010") to 4 mm (.156"). In addition, Valco valves offer the widest range of rotor and body materials of any valve available, with alloys and polymer composites capable of meeting virtually any system requirement. All models can be ordered in manual, pneumatic, or electrically actuated versions.

• For additional information on Gas Chromatography Valves
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 Diaphragm valves for GC

A diaphragm valve consists of plungers and ports arranged in a circular pattern, with the plungers controlled by the reciprocating action of two air actuated pistons. Extremely long lifetime (typically 1,000,000 cycles at ambient temperature; approximately 500,000 cycles at elevated temperatures), very short actuation time (10 milliseconds), minimum internal dead volume, and reliability have made this type of valve very successful in process gas chromatography for both sample injection and column switching. Our new miniature version features 1/16" or 1/32" zero dead volume fittings, and is the first to offer a 10 port configuration in addition to the 6 port and internal sample 4 port models.
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 Flanged fittings

The fitting most commonly used with low pressure plastic valves is the Cheminert tube end fitting consisting of a polypropylene nut retained on the polymeric tube by a flange formed with a specially designed flanging tool. This is an excellent method for connecting plastic tubing, as there is no possible reduction of the inside diameter and no binding or twisting of the tubing when the fitting is tightened. These fittings are widely used in biological applications and flow injection systems, with a variety of adapters and connectors available to allow connection to virtually any system.
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 Flangeless fittings

The Cheminert flangeless tube end fitting eliminates the flanging tool required with the standard tube end fitting. The one-piece collapsible ferrule makes up on the tube as the nut is tightened. The nut turns freely on the tubing, eliminating any possibility of flow restriction, cracking, or even unscrewing that can occur when plastic tubing is subjected to twisting as fittings are connected. This type of fitting can be used with any type of tubing.
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 Compression fittings

The two piece compression fitting, in which a ferrule is compressed onto the tube as a nut is tightened, offers reliability in high pressure situations and in connecting metal tubing. One piece compression fittings (nut and ferrule combined) are generally not as effective, since the sealing surface rotates as the tightening force is applied.

There are many manufacturers of fittings based on the compression concept: indeed, there is an incredible selection of connectors, adapters, and accessories available. Our thirty years of designing and manufacturing fittings specifically for chromatography have convinced us that our fittings are the best in the world.
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