Bob Flitney’s research while affiliated with BHR Group and other places

This year the features review appears slightly later than usual, so we are covering rather more than 12 months. And, as I have now been involved with Sealing Technology for ten years I thought that it would be interesting to also look back to my first review which covered the period May 2003 to May 2004.

A detailed numerical understanding of elastomer and plastic seals for dynamic applications is limited compared with current knowledge covering seals that use ‘hard’ materials, such as clearance and rotary mechanical face seals. Some of the key testing and research that has provided a thorough understanding of elastomer seals – enabling their empirical development over the last 50 years – is reviewed. The numerical analysis of rotary shaft lip seals is now well established and this is compared with practical experience.

Features during the last year have included reciprocating, rotary and static seals. Elastomer materials have received considerable coverage with some particularly useful application information being published. Special requirements and considerations applicable to the food and wind power industries have also been covered.

With the ever increasing search for sources of renewable energy wind power generation has become the focus of considerable attention. The trend for larger turbines, efforts to increase the efficiency and the desire in more crowded countries with plenty of coastline, such as UK, Netherlands and Denmark to position the turbines offshore leads to additional demands on reliability. This feature reviews some of the sealing applications involved, the seals that are used and solutions which are helping to improve both efficiency and reliability.

Following suggestions that an informal discussion group be formed to work towards improved specification for hydraulic piston rod surface texture a meeting took place in Stuttgart on 6 October 2008. The discussion attended by four seal manufacturing companies and three cylinder manufacturers proved that there is considerable interest in this topic, and demonstrated a commitment to progress the work further.

Some suppliers appear to be rather optimistic with the temperature ranges claimed for elastomer materials. This can lead to very expensive failures and in the long term could potentially cause a loss of confidence in elastomer seals, this may even have happened in some cases. The establishment of some sensible guidelines is long overdue. Perhaps the elastomer seal industry should take the initiative to protect its own reputation.

The replacement of hard chrome as a wear and corrosion resistant coating is receiving considerable attention in certain application areas. One of the primary applications of interest to the sealing community is the coating of hydraulic cylinder piston rods. This feature looks at the background behind this situation, which is both environmental and commercial, some of the alternative coatings and their effect on seal performance.

The features published in Sealing Technology over the last 12 months have been quite evenly divided between rotary, reciprocating and static seals. Complementing these have been articles on materials, new testing techniques for dynamic seals, standards, emissions and a general overview of the industry. This feature reviews the progress that we have seen this year.

This feature aims to provide a broad overview of current sealing technology. Almost every item of industrial and domestic equipment has some form of seal to either retain or exclude fluid and/or contaminants, so there is plenty of opportunity to learn from the activities of a wide range of disciplines. Static, reciprocating and rotary seal developments will be reviewed across a wide selection of industries.

The feature articles in Sealing Technology over the last year have included a wide variety of rotary seal designs, reciprocating seals and static seals. In addition elastomer material developments, emissions legislation and research work have been discussed. Contributions have varied from updates on standards to detailed numerical analysis. This feature is intended to provide an overview of the topics covered during the year.