Steam quality
Understanding steam quality and its vital role
Steve Bishop discusses the important role of steam quality in decontamination and tackles some key questions, including: how can we solve the ‘trilemma’ of service resilience, improved quality and decarbonisation challenges?
Steam is a vital element of sterile services and one that is all too often taken for granted. It is the predominant (indeed default) sterilisation media for many applications, yet often seen as a mere “utility” that is surely always delivered as required under all circumstances. Yet sometimes, the signs are right before us that all may not be as it should be with this critically important element in our ‘sterilisation armoury’. Corrosion rates on re-useable instruments, increased processing times (or even reprocessing) for sterilisation loads, repeated daily validation test failures on steam sterilisers, wet loads after processing, requirement for increased drying times and intermittent load failures due to temperature shortfall; these can all be indicative of problems with steam quality. This raises some important issues and questions, including: why is steam used in sterilisation? How do we define ‘steam quality’? How should we measure and assess this? What is the impact of not having a sufficient quality of steam? What’s the difference between steam quality and the grade of steam we use ? What aspects of our steam system/plant or their use can adversely impact steam quality? What are the practical steps we can take to mitigate the risks involved? How can we solve the ‘trilemma’ of service resilience, improved quality and decarbonisation challenges? Delegates at the recent Decontamination and
Sterilisation Conference 2024 in Birmingham were provided with some valuable insights into these issues thanks to our team from Spirax Sarco Group. We’d like to share some of these within this article and hope it may empower you to meet these challenges head on – or maybe even embrace them with renewed confidence.
Why is steam used in sterilisation? HTM01-01 Part C (1.4) directly references steam as being the preferred sterilant due to its superior sterilising qualities. So let’s just unpick that for a minute, in order to understand why it
might be considered “superior”, or indeed proven to be so. Steam is a unique heat transfer fluid – indeed
it has often been called “the energy fluid” due to the very particular characteristics and properties that it has. Steam is a vapour – moving from one place to another as a result of pressure differential. This also means it has great capabilities when it comes to penetration of any sterilisation load – allowing ready ingress across a huge range of equipment materials and profiles, ensuring complete and consistent item sterilisation. Steam, of course, is also hot and these higher
temperatures (typically between 120-140°C) are critically important when it comes to ensuring the destruction of a wide range of potentially harmful microorganisms, including heat- resistant bacterial spores. In order to do so, it is vital that temperatures are maintained for the required duration of the process, while the high total heat energy content in steam is also vital. Steam sterilisation is also a quick and versatile process when compared to many other sterilisation methods and does not leave behind any chemical residues or other bi-products on the equipment being processed – a major benefit for increasingly busy decontamination
and sterilisation departments, where additional processing may cause surgical delays. With proven reliability and performance over time, alongside cost-effectiveness when viewed against other methods, it is clear that steam will remain a vital element of decontamination for some time. However, we will only be able to utilise these unique characteristics of steam if it is delivered to the process in accordance with the right quality standard.
What exactly is steam quality? Naturally, we should challenge ourselves and other stakeholders to consider “what is steam quality?”, as well as seeking answers to “how should we assess and measure this?” and “is there a difference between ‘steam grades’ and ‘steam quality’?” Let’s start by answering the easy questions
first…Steam grade is most certainly a different consideration than that of steam quality. Various ‘grades of steam’ can be raised/ produced and these are largely dependant upon the water source from which the steam has been produced and the risks in relation to any remaining physical debris within the steam itself. We usually categorise four key grades of steam in common use: plant steam,
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