- Email: [email protected]
Forthcoming events
CONFERENCES
NBR with improved ozone resistance in hydraulic equipment applications Busak+Shamban in Germany has announced a new nitrile elastomer (NBR) which is designed to provide an economical material with good ozone resistance. The reason for this development is to help avoid cracking when seals are stored in an elongated state in a sub-assembly. The problem was highlighted by a hydraulic equipment manufacturer, which experienced seal leakage on systems fitted to excavators after a very hot summer. There had been no previous problems, and the cause was found to be ozone cracking. The fluid connections are often of a conical design, so a connection is maintained under high pressure. They can include a small cross-section O-ring, usually manufactured in NBR, because of the good elongation properties of
this material. They are designed to stretch in the seal groove between 5% and 17%, to stop movement. The hydraulic tube fittings are usually stored as ready-to-use subassemblies, with the seals fitted in the elongated state. When stored, the seals have been found to suffer from ozone attack, and standard NBR shows signs of cracking, especially when it is stored at relatively high temperatures. To solve this problem, the new NBR material was developed.
Forthcoming events Valve conference to discuss sealing The Autumn conference of the British Valve & Actuators Association (BVAA) will be held in Birmingham, UK on 6 December. Three of the five papers to be presented are directly concerned with seals: • Explosive decompression resistant elastomers (Greene Tweed & Co Ltd). • High performance elastomers (James Walker & Co Ltd). • How does an end-user achieve effective valve life cycle costs together with the reduction of fugitive emissions in the field? (BK Solutions). Contact details are in the Events Calendar on page 15.
Editor’s comment: It is disappointing that this meeting clashes with the IMechE Seminar, almost within walking distance, on the same day. Modesty and editorial impartiality preclude me from recommending one event above the other.
Papers requested by STLE Contact: Busak+Shamban GmbH & Co, Handwerkstrasse 5–7, D-70565 Stuttgart, Germany. Tel: +49 711 78640, Fax: +49 711 7864 344, Email: bsdeutschland@ busakshamban.com, Web: www.busakshamban.com
There is still time to submit a paper to the sealing sessions at the STLE Annual Meeting in Calgary, Canada in May 2006. Abstracts may be submitted directly on the STLE website, or you may contact the paper solicitation chairman, Shifeng Wu. Contact: Shifeng Wu, A.W. Chesterton Co, 860 Salem Street, Groveland, MA 01834, USA. Tel.: +1 978 469 6786, Email: [email protected], Web: www.stle.org/offer_of_paper/index.cfm
Conference Focus – Three events in two weeks dilute attendance With two seal-related conferences and the ISGATEC sealing technology exhibition in a two-week period, there were too many events within a short timescale in Europe during October. If this trend contiues the events will gradually become more specialized, and there will be less crossover between the various seal disciplines. A total of four delegates, including the Editor, attended both the Poitiers and Antwerp conferences.
Advanced topics and technical solutions in dynamic sealing This was the title given to the 4th EDF/LMS Poitiers Workshop, which took place at the Futuroscope near Poitiers, France on 6 October. The meeting was jointly organized by Electricité de France (EDF) and the School of Mechanics & Solids (LMS) of the Université de Poitiers. The meeting was attended by some 50 external visitors from industry and other academic institutions. The purpose of these meetings is to provide a forum for industrial-based presentations and discussions. The success of this approach is demonstrated by the high proportion of industrial participants from seal, pump, compressor and turbine manufacturers, with presenters and delegates from seven countries.
4
The invited keynote presentation was given by Professor Dara Childs from Texas A&M University, who reviewed progress in annular gas seals for compressors, covering the introduction of swirl brakes and advances in honeycomb and hole-pattern seals. The problems with applying theoretical models to predict labyrinth seal performance was also highlighted, with the presenter suggesting that the use of CFD is the most sensible approach. The paper of Pugachev and colleagues provided details of work in this area, but it seems that there is still plenty of work to do, and that extensive computer resources and time are required to achieve useful results. Staubli and colleagues from the Hochschule für Technik und Architektur in Lucerne, Switzerland presented work on the annular turbulent seals in pumps. This is part of an ambitious project to model the entire pump. A new project is work on shoed brush seals by Texas A&M, with seals supplied by Cross
Manufacturing in the UK. This provided considerable interest, with leakage claimed to be 30% less than a conventional brush seal. Interesting work for similar applications is that on compliant finger seals by Braun et al. from the University of Akron. A presentation providing details of the use of analytical work as part of an extensive exercise to improve seal reliability was provided by Mathewson, on work to improve the life of seals for PWR reactor coolant pumps by Flowserve companies. A more specialized paper dealing with one aspect of the same subject was a study of the O-rings on hydrostatic seals by Galenne and colleagues from Poitiers University. During the breaks there were also a number of poster presentations to provide some interesting reading. The papers presented were as follows:
Keynote presentation • Recent advances in the rotordynamic behavior of annular gas seals, by Dara W. Childs (Texas A&M).
Seminar papers • Validation of CFD predictions for gas labyrinth seals, by A. Pugachev (Oriel State University, Russia), M. Deckner and K. Kwanka (TU München). • A discussion of numerical schemes to determine rotordynamic coefficients of turbulent
Sealing Technology November 2005
NBR with improved ozone resistance in hydraulic equipment applications Busak+Shamban in Germany has announced a new nitrile elastomer (NBR) which is designed to provide an economical material with good ozone resistance. The reason for this development is to help avoid cracking when seals are stored in an elongated state in a sub-assembly. The problem was highlighted by a hydraulic equipment manufacturer, which experienced seal leakage on systems fitted to excavators after a very hot summer. There had been no previous problems, and the cause was found to be ozone cracking. The fluid connections are often of a conical design, so a connection is maintained under high pressure. They can include a small cross-section O-ring, usually manufactured in NBR, because of the good elongation properties of
this material. They are designed to stretch in the seal groove between 5% and 17%, to stop movement. The hydraulic tube fittings are usually stored as ready-to-use subassemblies, with the seals fitted in the elongated state. When stored, the seals have been found to suffer from ozone attack, and standard NBR shows signs of cracking, especially when it is stored at relatively high temperatures. To solve this problem, the new NBR material was developed.
Forthcoming events Valve conference to discuss sealing The Autumn conference of the British Valve & Actuators Association (BVAA) will be held in Birmingham, UK on 6 December. Three of the five papers to be presented are directly concerned with seals: • Explosive decompression resistant elastomers (Greene Tweed & Co Ltd). • High performance elastomers (James Walker & Co Ltd). • How does an end-user achieve effective valve life cycle costs together with the reduction of fugitive emissions in the field? (BK Solutions). Contact details are in the Events Calendar on page 15.
Editor’s comment: It is disappointing that this meeting clashes with the IMechE Seminar, almost within walking distance, on the same day. Modesty and editorial impartiality preclude me from recommending one event above the other.
Papers requested by STLE Contact: Busak+Shamban GmbH & Co, Handwerkstrasse 5–7, D-70565 Stuttgart, Germany. Tel: +49 711 78640, Fax: +49 711 7864 344, Email: bsdeutschland@ busakshamban.com, Web: www.busakshamban.com
There is still time to submit a paper to the sealing sessions at the STLE Annual Meeting in Calgary, Canada in May 2006. Abstracts may be submitted directly on the STLE website, or you may contact the paper solicitation chairman, Shifeng Wu. Contact: Shifeng Wu, A.W. Chesterton Co, 860 Salem Street, Groveland, MA 01834, USA. Tel.: +1 978 469 6786, Email: [email protected], Web: www.stle.org/offer_of_paper/index.cfm
Conference Focus – Three events in two weeks dilute attendance With two seal-related conferences and the ISGATEC sealing technology exhibition in a two-week period, there were too many events within a short timescale in Europe during October. If this trend contiues the events will gradually become more specialized, and there will be less crossover between the various seal disciplines. A total of four delegates, including the Editor, attended both the Poitiers and Antwerp conferences.
Advanced topics and technical solutions in dynamic sealing This was the title given to the 4th EDF/LMS Poitiers Workshop, which took place at the Futuroscope near Poitiers, France on 6 October. The meeting was jointly organized by Electricité de France (EDF) and the School of Mechanics & Solids (LMS) of the Université de Poitiers. The meeting was attended by some 50 external visitors from industry and other academic institutions. The purpose of these meetings is to provide a forum for industrial-based presentations and discussions. The success of this approach is demonstrated by the high proportion of industrial participants from seal, pump, compressor and turbine manufacturers, with presenters and delegates from seven countries.
4
The invited keynote presentation was given by Professor Dara Childs from Texas A&M University, who reviewed progress in annular gas seals for compressors, covering the introduction of swirl brakes and advances in honeycomb and hole-pattern seals. The problems with applying theoretical models to predict labyrinth seal performance was also highlighted, with the presenter suggesting that the use of CFD is the most sensible approach. The paper of Pugachev and colleagues provided details of work in this area, but it seems that there is still plenty of work to do, and that extensive computer resources and time are required to achieve useful results. Staubli and colleagues from the Hochschule für Technik und Architektur in Lucerne, Switzerland presented work on the annular turbulent seals in pumps. This is part of an ambitious project to model the entire pump. A new project is work on shoed brush seals by Texas A&M, with seals supplied by Cross
Manufacturing in the UK. This provided considerable interest, with leakage claimed to be 30% less than a conventional brush seal. Interesting work for similar applications is that on compliant finger seals by Braun et al. from the University of Akron. A presentation providing details of the use of analytical work as part of an extensive exercise to improve seal reliability was provided by Mathewson, on work to improve the life of seals for PWR reactor coolant pumps by Flowserve companies. A more specialized paper dealing with one aspect of the same subject was a study of the O-rings on hydrostatic seals by Galenne and colleagues from Poitiers University. During the breaks there were also a number of poster presentations to provide some interesting reading. The papers presented were as follows:
Keynote presentation • Recent advances in the rotordynamic behavior of annular gas seals, by Dara W. Childs (Texas A&M).
Seminar papers • Validation of CFD predictions for gas labyrinth seals, by A. Pugachev (Oriel State University, Russia), M. Deckner and K. Kwanka (TU München). • A discussion of numerical schemes to determine rotordynamic coefficients of turbulent
Sealing Technology November 2005