What is EN 285?

EN 285 is formally titled EN285 – Sterilization – Steam sterilizers – Large sterilizers, and is the European harmonised standard for large steam sterilizers. ‘Large’ is defined as having a useable chamber volume that can accommodate a single sterilization module (300 mm x 300 mm x 600 mm), hence having a chamber volume greater than approximately 60 litres.

When was EN 285 published?

It was originally published in 1996. As part of the normal review process of standards, EN 285 was revised and published in 2006.

An amendment was proposed to EN 285 soon after the 2006 version was finalised. This was published as EN 285:2006+A1:2008.

What tests are required to conform to EN 285?

EN 285:2006+A1:2008 has a table (table 4) that lists the tests that are required in order to qualify a sterilizer to EN 285, which are described as either ‘type tests’ or ‘works tests’.

What is a type test?

EN 285 (clause 3.38) defines a type test as a ‘series of checks and tests for a particular design of sterilizer to demonstrate compliance with the requirements of this European Standard’.

What is a works test?

EN 285 (clause 3.43) defines a works test as a ‘series of tests performed at the manufacturer’s works to demonstrate that each sterilizer will comply with its specification’.

Does a sterilizer manufacturer need to perform all of the type tests specified in EN 285?

A sterilizer manufacturer needs to perform all of the type tests in order to verify that the design of the sterilizer complies with the standard.

What did the amendment change within EN 285?

EN 285:1996 specified a series of tests to be conducted in order to qualify a sterilizer; one of these tests was the rubber load test. This test was specified as a type test. The revised EN 285:2006+A1:2008 changed from a rubber load type test to a hollow load type test. This change was as a result of a multi-laboratory study that showed that the rubber load test was not sufficiently sensitive and would be improved by implementing the hollow load test.

What is the rubber load test?

A type test involving lengths of rubber tubing with biological indicators inserted within the bore of the rubber tubing at predetermined locations.

What is the hollow load test?

A type test involving the hollow load process challenge device (PCD) as specified in EN 867-5 with a chemical indicator at the terminal end of the PCD.

What are the implications of this change?

Sterilizer manufacturers who conduct the type testing for each design of their sterilizer will have to use the hollow load test in place of the rubber load test.

What is the Bowie Dick test?

The Bowie Dick test is a daily steam penetration test that is performed at the commencement of each day that the steam sterilizer is used. It is a requirement of EN ISO 17665-1 to perform this test.

Is the hollow load test the same as the Bowie Dick test?

No; the hollow load test is a type test specified in EN 285:2006+A1:2008. It is not intended to be used other than as a type test by the sterilizer manufacturer. The Bowie Dick test is a test that is intended to be performed daily by the end user.

Richard Bancroft December 2008