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October 28, 2010
This month, rather than dedicating an entire issue to a specific make or model of sterilizer (such as we did with Decoding the Statim) we’re going to discuss general theories of operation and steps to take to troubleshoot steam or chemical vapor sterilizers. These concepts can be applied to most any brand or model of sterilizer.
First of all, many common problems associated with sterilizers crop up due to maintenance and upkeep issues. We have covered general sterilizer maintenance in a past edition, Sterilizer Maintenance, and we strongly recommend reviewing it and printing it for your staff before moving forward. The first step should always be proper maintenance. Nonetheless, even with proper maintenance, errors can occur. Many state and local agencies recommend weekly spore testing of sterilizers, in part due to the many things that can go wrong.
A number of the tests you will need to perform will require a multimeter (see our issue on Multimeters for basics on using this helpful tool). Most components can be tested with the sterilizer unplugged. It is best to have any electronic component unplugged when servicing if possible. Regardless, always exercise caution when checking electronic components and equipment.
Two of the most commonly observed problems with sterilizers are failure to achieve pressure or improper temperature (either too low or too high). This month, we’ll focus on pressure, next month we’ll cover temperature.
Low pressure is normally the only pressure-related concern encountered (persistent high pressure is rare and obvious as the safety valve will crack releasing pressure). Low pressure can be attributed to one of three basic causes:
The first step in resolving pressure issues is to narrow down which of these three primary categories is causing the problem.
What does the unit thermometer/temperature gauge read? If it is at or above 135° C (275° F) you do not likely have a heating problem. Have you verified this temperature is achieved using a lag thermometer? In this case, move on to the next possibility, water. (If your unit fails to heat or does not achieve adequate heat, you’ll need to wait for next months Part 2 – Temperature Issues.)
Almost all sterilizers incorporate some sort of water filter. Usually, there is a filter in the chamber at the point water flows into it. Check this filter for signs of wear or clogging. Changing this filter should be part of your annual maintenance routine. Nonetheless, filters can wear prematurely. There is often a filter in the reservoir as well. A simple visual inspection of the filters should be adequate to determine their condition. If they don’t look clean, they aren’t and should be replaced. These filters are normally sintered bronze or stainless steel so they should have the appropriate metallic color.
While in the reservoir checking your filter (or to see if there is one – not all sterilzers will incorporate this filter), check the water level. Make certain that the reservoir is properly filled.
Speaking of water – this might also be a good time to verify that nothing but distilled or de-ionized water is being used in your autoclave. Using tap water or similar untreated water will certainly lead to much more common clogs and other potential issues (such as staining of instruments).
If your filters check out, examine the reservoir itself and the water line that feeds from the reservoir to the chamber. These lines can also become clogged over time. Using a small cleaning brush or similar device may be one of the most effective ways of checking the water line.
Usually the water flows through some sort of valve (e.g. solenoid), checking this valve for clogs or function can be more involved and the steps to check it will vary depending on the specific make and model of your sterilizer. Call our tech support staff to speak about the particulars of your sterilizer to diagnose valves.
Note: The things we suggest checking are presented in the order in which they should be checked (most likely to least likely as well as simplest to most involved to check).
Watch next month for Part 2: Sterilizer Troubleshooting – Temperature Issues.
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