Steam Quality Testing ISO EN285
Autoclaves use steam supplied by a steam generator. The quality of the steam partially determines the overall success of sterilization with the autoclave. For the validation of steam quality from a steam generator, our validation experts adhere to the standard EN 285.
Chemical Steam Quality Control
A too high content of non-condensable gases leads to inefficient heat transfer. This results in inefficient or incomplete sterilization. Overheated steam has less capacity to transfer heat than saturated steam. The steam must first be cooled to the condensation temperature before latent heat can be released. This will cause the steam volume to reduce more slowly, creating less vacuum and thereby lowering the penetration power of the steam.
When in contact with cooler objects (e.g. pipes and air), steam condenses. If the steam humidity is too high, the condensate can clog the pores in the packaging material. This reduces the penetration power of the steam, leading to inefficient or incomplete sterilization, and also to wet loads.
Agidens controls the chemical quality of the steam through analysis in a qualified laboratory.
“To safely reuse surgical instruments in hospitals and pharmaceutical companies, they are cleaned, maintained, packaged and sterilized in steam sterilizers after use. To demonstrate that steam sterilizers are functioning correctly, they must be periodically validated. The High Council of Health (HGR 9256 – May 2017) even recommends annual steam quality tests.”
Validation Process
NCG
Measurement of non-condensable gases in steam: steam from the generator is cooled with cold water, releasing gas that is then collected in a burette.
Superheat
This test measures the overheating of the generated steam. The temperature is measured using a temperature probe.
Dryness
The dryness or saturation of steam refers to the ratio between liquid and gaseous water in the steam. For autoclaves, it is essential that the amount of liquid in the steam is limited to ensure a uniform and complete distribution of steam in the autoclave. This is tested by connecting the steam to a Dewar bottle (similar to a thermos) filled with a predetermined volume of water. The weight increase upon heating to a predetermined temperature is then used, in conjunction with steam tables, to determine the dryness.
Sample Analysis (optional)
Feed water and steam condensate are collected and sent to specialized laboratories for chemical contamination analysis.
Contact us for more information
Agidens has over 25 years of experience in validation & compliance and is a well-known name in the hospital world. Our clients trust us because of our expertise and ‘no nonsense’ approach, and with reliable service, we are a long-term partner.
