Troubleshoot It: Steam Sterilizers

Abstract

Editor's note: With this issue of BI&T, the Troubleshoot It column will be featured in a question-and-answer format. Please submit your questions to Susan Gillespie at sgillespie@aami.org.Q: How do I determine the cause of build-up or rust in the lines of a steam sterilizer?A: Most likely, there is more than the rust issue going on here. Rust is usually a symptom of other problems. Before one can go too far with this issue, testing the water quality and steam quality will help to formulate an educated guess as to the problem and determine next steps. Also, one will need to know whether a water purifier is used (at least for the final rinse).A water quality test will evaluate the biological, mineral, and chemical content of the water. Specifically in this application, we are concerned with the mineral content. Certain minerals such as iron and sulfates can cause scaling and rust on instruments. Someone skilled in water quality should evaluate your test results. Mineral analysis will be given in parts per million and show content of minerals in the water such as calcium, magnesium, manganese, iron, copper, and zinc. It will also determine the acidity or pH and hardness of the water, as well as give the concentration of nitrates, sulfates, and other chemical compounds.A steam quality test will evaluate the quality, purity, and quantity of the steam provided to the sterile processing equipment. The steam provided should be a continuous, adequate, and saturated supply. The most critical aspects of steam quality are the dryness and the level of noncondensable gas. Steam dryness should be between 97% and 100%. The noncondensable gas should be a level that does not impair steam penetration in sterile loads. To achieve these suggested levels, steam traps need to be appropriately placed and replaced and steam lines need to be insulated. Steam quality should be maintained by monitoring and control processes. Your maintenance department or hospital protocol usually sets these processes.The feed water source to the boiler should minimize the presence of potential contaminants in the steam. This water needs to be treated so that its chemistry does not damage the boiler or steam lines, and any additives need to be monitored. When necessary, in-line filters should be used to remove particles such as scaling that may occur as the system ages. If these filters are used they should be placed as close to the sterilizer as possible. Remember that the hardness and pH of water affect the purity of the steam generated by the boiler.Whether your facility uses a water purifier or “distiller” is also an important question to ask. A distiller may be the best solution as distilling removes everything from the water, giving you absolutely pure water. A water purifier removes certain minerals but does not removing everything from the water.While these things are a good starting point, a very important point to consider is where the rust is appearing. That is, is it on the instruments, on the packs, or on both? Is the problem constant or is it only happening with certain types of instruments? Each one of these problems will lead one on a different problem-solving path. For example if the rust is on the instruments it could be water quality, wash cycles that are too short, or a detergent issue. Likewise, if the rust is on the packs then the issue is probably not generic to the sterilizer but probably the steam before it comes in the sterilizer. If rust is only on specific instruments, the problem could very well be with the procedure used in the beginning to remove contaminants at the beginning of the sterilization process.In conclusion there are many steps that may need to be taken to get to the bottom of the rust issue. One will never go wrong by starting with water and steam quality tests. In fact, starting with these tests may just save the biomedical equipment technician a lot of wasted time.