Valves player offers new one-piece fitting

Valves and fittings manufacturer Vici is offering a new one-piece fitting using Victrex PAEK high-performance polymer.

The company claims the injection moulded Victrex HT can withstand the high pressures inherent in liquid chromatography systems and is, in fact, capable of withstanding pressures of up to 1,000 bar (14,500 psi).

The pressures required in liquid chromatography have been rising steadily for over five years, given that the particles of the separation materials (usually modified silica gels) now frequently have a grain size of two micrometres or less. Consequently, substances within mixtures can be separated more quickly, with identical efficiency.

Vici has introduced a new one-piece fitting capable of withstanding pressures when tightened by hand of up to 500 bar (7,250 psi). By way of comparison, 350 bar (5,000 psi) was the limit for conventional PEEK fittings. Provided the carbon-fibre reinforced Victrex HT fittings are tightened with an appropriate tool, they are suitable for significantly higher pressures of up to 1,000 bar (14,500 psi), confirmed Dr Andre Hütz, product manager at Vici International, based upon testing the company has performed.

Such higher pressures occur between pump and column in ultra-high-performance liquid chromatography systems (UHPLC) and require that the stainless steel connecting capillaries used for the high-pressure range are fastened with appropriate fittings. Many UHPLC applications are carried out in a pressure range of approx. 600-800 bar, which means that the steel capillaries used between pump and column must use this type of fitting to provide a pressure-tight connection between system components.

Dr Andre Hütz, product manager at Vici International said: “Assisted by Victrex and its material and processing expertise, we have developed and commercialised a new product in this segment to offer users greater flexibility, reusability and above all easier handling compared to steel screw fittings. Also, being manufactured by injection moulding, it is favourable in cost terms, too. We have performed tests showing that, when tightened by hand, the new Victrex HT fittings can be used at 500 bar and above. When tightened with a tool, they can also be reused at least three times after first use at a test pressure of 950 bar.”

Vici has confirmed that the performance claims are based upon testing it has performed. According to Vici test documentation, results depend on the level of tightening.