Feature

Fluoropolymer Linings Facilitate Leak-free Distribution of Aggressive Media

Posted on 27 January, 2010 | Tags: Case Study

Magnetic drive pumps from Richter Chemie-Technik GmbH, lined with DuPont™ Teflon® PFA and PTFE, have been in operation at Chemada for more than fifteen years. They are used for the reliable and leak-free distribution of aggressive and highly toxic media containing bromide.

Case History
The Israeli chemical company Chemada uses MNK-B magnetic drive pumps from Richter Chemie-Technik GmbH for the distribution of highly reactive and toxic media containing bromide. All parts of the pumps which come into direct contact with the media are lined with either DuPont™ Teflon® PFA or Teflon® PTFE. These fluoropolymers demonstrate excellent resistance to a number of chemicals, as well suitability for use at temperatures of 200 °C in pumps. Such properties mean that the materials make a significant contribution to the reliable and leak-free performance of the pumps, thus rendering unforeseen pump failures a thing of the past.
Previously Chemada had used pumps with mechanical seal rings. However, such designs with mechanical seal rings require a high level of supervision and maintenance, which increases when used with aggressive media containing bromide. For this reason, Chemada chose to use the sealless magnetic drive pumps from Richter Chemie-Technik. A wise decision, since confirmed by over fifteen years of service at Chemada without any unplanned pump downtimes and thus considerable savings for the company.
Richter Chemie-Technik coats the housing, impeller and rotor of its magnetic drive pumps with a thick layer of Teflon® PFA, which is processable as a thermoplastic. The separating can, which hermetically seals the product volume against the atmosphere, is made entirely of Teflon® PTFE. This ensures that no medium containing bromide comes into contact with any metal parts, which it would otherwise corrode and create the potential for leakage. The grade of Teflon® PFA used in this application demonstrates higher thermal stability versus other PFA grades.
For this reason, the customer can process the material at higher temperatures and, as a consequence, with a lower melt viscosity. The high stress crack resistance of Teflon® PFA ensures the longevity of the lining. During injection moulding, the fluoropolymer does not stick to the tool walls, meaning that that the moulded part ejects easily from the tool. Typical applications for Teflon® PFA are extruded pipes and tubes for the distribution of aggressive fluids at high pressure, as well as the linings of pipes, pumps, valves and fittings for use in the chemical industry.

Narendra Thakkar is Sales and Marketing Manager, Fluoropolymer Solutions (Teflon® and Tefzel®), E I DuPont India Pvt Ltd
E-mail: thakkar@ind.dupont.com