Decon Pete – autoclave testing and validation

decon peteThis month Decon Pete takes a look at the testing and validation protocols for washer disinfectors and autoclaves.

The testing protocols for washer disinfectors fall into three main categories; weekly, quarterly and annual tests.

A weekly protein residue test should be carried out on one of the instruments that has been through the WD cycle. UK guidance recommends the use of a rinse aid in order to help reduce water spotting on stainless steel instruments. This can cause rusting and inhibits the lubrication of joints. This is a particular concern in the case of forceps.

If an instrument fails the protein residue test, firstly, double-check that the washer disinfector is not displaying any visible error codes and that it contains detergent. Then run another cycle.

If the test fails again, consult an engineer. This could be indicative of a problem with the washer disinfector itself.

Weekly safety checks are also required for washer disinfectors to confirm there is no visible damage that could invalidate its processes.

This includes checking that rotor arms function without stiffness, the door opens and closes smoothly and the rubber, or silicone, gasket around the door is not damaged.

Although there is no test as such for these checks, you should record and file them as part of the practice’s decontamination processes.

Less frequent testing

On a quarterly basis, washer disinfectors must complete a cleaning efficacy test (soil test), using a PCD (process challenge device) and CEI (chemical efficacy indicator).

It’s important to note that this is a manufacturer-led test; therefore you should adhere to their guidelines.

However, in the absence of any manufacturer guidance, follow UK guidance advice.

Finally, all washer disinfectors require annual validation by an accredited engineer.

The use of washer disinfectors is considered best practice, and currently not mandatory in England and Wales.

As mentioned in February’s article, these help eliminate the need for manual cleaning and reducing the risk of sharps injuries.

Manual cleaning

Following a wash cycle, the dental team must visually inspect instruments and if debris is present. The instrument cannot be sterilised.

UK guidance states that materials such as cement should be cleaned straightaway. Research suggests that doing so makes the cleaning process easier.

There are several specialist pre-wash foams and sprays available. These help to break down materials and start the decontamination process before cleaning takes place.

Approximately 70% of dental practices still conduct some sort of manual cleaning. Although it is still acceptable and sometimes necessary, manual cleaning is very difficult to validate due to inconsistencies in individuals cleaning methods.

Therefore, it is important to have protocols in place, such as a set emersion technique, which the team must follow and document.

Tests for autoclaves

Vacuum and non-vacuum autoclaves require several tests. Firstly if your autoclave is not fitted with a data logger or printer, then an ACT (automatic control test) that tests the parameters of the autoclave needs completing every morning.

This test necessitates the use of a class 6six indicator (also known as a TST), which measures time, steam and temperature within the autoclave. This indicator will only change colour when the autoclave meets three specific criteria:

  • The time has been achieved (a minimum of three minutes, or whatever time the manufacturer advises)
  • The steam has penetrated the strip and
  • The temperature has been achieved (134°C – 137°C).

If the autoclave doesn’t meet any of these parameters, the indicator will not change colour.

Use a stopwatch to monitor the min/max temperature time and sterilisation time. Note these times in a logbook. When comparing temperature readings to previous days, they should remain the same.

In the case of vacuum autoclaves, they require a steam penetration test once a day, using either a Helix device or Bowie and Dick.

A printable data logger automatically records and prints out this test. It provides written confirmation of sterilisation times, temperature, and whether the autoclave passed the test successfully. It then creates a unique batch number.

If you have a printer rather than a data logger, keep the test printouts in airtight bags to prevent the ink fading. Thereby providing documentary evidence of the effectiveness of the autoclave.

Autoclave maintenance

At the end of each day, physically drain the inner water chamber, where clean and dirty water resides, wipe it with a lintfree cloth and leave it to dry. This helps prevent the formation of biofilm.

To keep the autoclave in good running order, dry door seals and gaskets after each cycle with a lintfree cloth. Change door gaskets every two-three months or at a frequency stated by the manufacturer.

Carry out a residual air tests and an air leakage test weekly. However, some autoclaves cannot perform these tests. In this case, consult the manufacturer for advice.

A decontamination engineer should annually validate all autoclaves and you should receive a test certificate.

In addition to the validation, autoclaves should also have an annual PVI (pressure vessel inspection) carried out in accordance with the PSSR 2000 and by a competent engineer.

Whether you chose to use an N, S or B class autoclave, it’s important that you always follow manufacturer’s guidance relating to testing and load types that each autoclave can accommodate.

Please contact me if you wish to discuss things further or need assistance in choosing the correct autoclave for your practice. Email me at [email protected] or visit for more details.

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Catch the previous Decon Pete column:

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