In response to "confusion" about the ATEX status of mechanical seals, the European Sealing Association (ESA) has issued a statement declaring that off-the-shelf mechanical seals are "machinery elements" and do not need ATEX Certificates of Conformity.

Although the ATEX Directive on equipment for use in potentially explosive atmospheres has been in place since 2003, "there is still a lot of misunderstanding about how it applies to mechanical seals," says ESA secretary-general, Dr Brian Ellis. "Some seal users have been asking manufacturers for ATEX Certificates of Conformity because they believe the seals they are buying are classified as ATEX components - but, in most cases, this isn`t so."

In February 2005, the ATEX Standing Committee issued a document to address the issue. It confirmed that any mechanical seal that is a standard or stock item is a machinery element and is thus not covered by ATEX.

However, the committee also added that in some unusual cases - such as seals developed for a particular application by manufacturers working with users - they could be classified as "engineered mechanical seals" and would require certification. Although ESA agrees with this, it believes that the term "engineered mechanical seals" might be causing confusion because it is not widely recognised.

EAS has published a position statement on the issue which can be downloaded from its Web site.