When water is heated in an open saucepan, small bubbles can seen forming. These are non-condensable gases and usually consist of air, though occasionally large amounts of carbon dioxide may be present. If we heat water in a closed boiler these gases will be present in the steam. The amount of gases in water is usually related to the water temperature, with cold water containing high levels of gases and hot water lower levels, though water chemistry can also have a big impact. Therefore, instead of supplying our sterilizers with steam we can sometimes be supplying them with a mixture of steam and these gases. Inside the sterilizer they have the same impact as air and can prevent steam penetration of the loads and therefore incomplete sterilization.
We test for these gases by bubbling a sample of steam through water and collecting the gases in a burette. By measuring the amount of gases and the amount of steam needed to produce these we can express the result as a simple %. EN 285 requires that the amount of gases should not exceed 3.5% (3.5 ml of gas/100 ml of steam condensate).
The KSA non-condensable gas test equipment is designed to be used semi-continuously and allows the test temperature to be varied. This allows different types of gases to be diagnosed. The equipment does not require a local source of water allowing for maximum flexibility/portability.
A brief introduction to Non-Condensable gas testing