Practice Tips #27: Troubleshooting Sterilizers (Part 1)

Rather than troubleshooting a specific make or model of sterilizers (such as we did with Decoding the Statim), we’re going to discuss general operation and troubleshooting of steam or chemical vapor sterilizers in Part 1. These concepts apply to most brands or models of sterilizer.

Proper Sterilizer Maintenance

First of all, many common problems with sterilizers crop up due to maintenance and upkeep issues. We covered general sterilizer maintenance and strongly recommend reviewing and printing it for your staff before moving forward. The first step should always be proper maintenance. Nonetheless, even with proper maintenance, errors 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 need to perform require a multimeter (see our Practice Tips on multimeters for basics on using this helpful tool). Best practice states that it is best to have any electronic component unplugged when servicing for safety concerns. 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.

Pressure

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:

Inadequate heat to create steam.Poor or no water flow into the chamber from the reservoir. This happens because of a clog somewhere, but could simply be due to lack of water in the reservoir.Pressure leak.

The first step to resolve pressure issues is to narrow down which of these three primary categories is causing the problem.

Heat

What does the unit thermometer/temperature gauge read? If it reads at or above 135° C or 275° F, you do not likely have a heating problem. Have you verified this temperature 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, read Part 2 – Temperature Issues.

Poor or No Water Flow

Almost all sterilizers incorporate some sort of water filter. Usually, the chamber has a filter at the point water flows into it. Check this filter for signs of wear or clogging. We recommend changing this filter as part of your annual maintenance routine. Nonetheless, filters do 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 made of 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 sterilizers do), check the water level. Make certain that the reservoir is properly filled.

TECH TIP: Use distilled or de-ionized water in your autoclave. Using tap water or untreated water leads to much more common clogs and other potential issues (such as staining of instruments).

If your filters check out, examine 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 effectively helps with checking the water line.

Usually the water flows through some sort of valve (e.g. solenoid), check this valve for clogs and function. It can be more involved than you expect, 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.

Pressure Leak

1. Observation. Watch the sterilizer as it pressurizes. Often, you can see steam escaping from a particular location. This can be a good indicator of where the leakage is occurring. For example, if you can see steam leaking around the door, replace the door gasket. It may be necessary and helpful to run a cycle with the cover removed from your sterilizer, so you can see where any leak originate.
2. Door Gasket. Check for signs of wear, cracks, chips, etc. Replace the door gasket every year, as part of routine maintenance. Exposure to heat wears on the material over time.
3. Safety Valve. Sterilizers have a safety valve to prevent over-pressurization. This valve can get stuck open and leak. Using a needle-nose pliers, pull the ring on the end of the valve to see if it moves. It should move with some effort and return. If it does not move or does not spring back when released, the safety valve has failed and should be replaced. Locate the safety valve inside the reservoir or at the back or your sterilizer. Shown below is the Validator Pressure Relief Safety Valve:
   
4. (Air) Bellows. Most sterilizers incorporate some sort of bellows as well. We recommend replacing this annually, but it depends on the sterilizer. Sometimes a visual inspection of the bellows gives you a good idea of its condition.
5. Electronic Component Failure. Many sterilizers (particularly automatic sterilizers) incorporate steam sensors and various types of electronic controls to control pressure. A failure of one of these components impedes proper pressurization. Call our tech support staff for particulars of testing electronic components of your sterilizer. To check most of these components you will need a multi-meter.

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).

Read the next Practice Tip for Part 2: Sterilizer Troubleshooting – Temperature Issues.