Written on 23.12.2011 - Technology
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TPU long-life diaphragms for industrial units

Diaphragms in industrial units, such as pumps, are subject to harsh conditions. For this reason, the Simrit business unit of the Weinheim-based German company Freudenberg Sealing Technologies has developed diaphragms of thermoplastic polyurethane that are particularly tough. According to the company, the so-called long-life diaphragms can increase the service lives of the units in which these components are installed by up to a factor of three – as compared to plants with conventional acryl nitrite butadiene rubber (NBR) components.

TPU long-life diaphragms from Simrit can reduce the life-cycle costs of units and can be delivered in larger series as well.

Diaphragms are important components not just for fluid pumps, industrial appliances and fittings, but also for applications used in building services engineering and in plant engineering and construction. Previously, mainly materials like NBR or ethylene propylene diene rubber (EPDM) have been used for these diaphragms. Due to increasing requirements to service lives and resilience under harsh environmental conditions, the Simrit experts are looking for new material solutions. TPU seemed to be a promising solution with its great parameters, such as higher tensile resilience and elasticity, great abrasion resilience, and best values in tear resistance and reverse bending resistance.

In order to verify these characteristics in actual applications, Simrit started an elaborate test series with diaphragms made from TPU for a supply pump application in which durability was particularly critical.

A large variety of TPU materials were examined. Simrit says it soon became clear, that the choice of the correct TPU material has a major influence on the life span. Initially, diaphragms made from pure TPU were used, later tests also included multi-component diaphragms which contained fabric inlay for structural optimisation or PTFE foil against highly aggressive media. Modern calculation and simulation tools used parallel to the test series achieved a comprehensive optimisation of the long-life diaphragm.

After these comprehensive test series and intense development work with different TPU materials, Simrit has been able to produce diaphragms from pure TPU as well as composite diaphragms with PTFE foil, fabric, and metal or plastic inserted parts, in high volumes. According to Simrit, the life span of units in which these components have been incorporated can be three times higher than that of units and machines in which the traditional NBR components have been used.