The operation of autoclaves is controlled by monitoring parameters including: temperature, pressure and processing time as well as steam penetration into the material.
Work tests are procedures to evaluate the quality and efficiency of the machine's performance to guarantee the user and patient safety.
Although the machines are equipped with an alarm system, systematic monitoring must be ensured by carrying out physical and chemical tests to confirm the correct functioning of the equipment.
If the work tests are not successfully passed, the autoclave must not be used and service by an authorised technician must be requested.
Work tests are carried out on an autoclave before the sterilisation cycle with an empty chamber.
What are the required autoclave tests?
Vacuum control test:
- Vacuum Test
Steam penetration test:
- Bowie Dick test
- Helix test
When should autoclave tests be performed?
The reference standard that specifies the performance requirements and test methods for class B autoclaves is UNI EN 13060.
Local and regional autonomy and discretion in implementing health-related regulations and standards have led to different requirements regarding the performance schedule of work tests.
It is however advisable to perform these tests daily.
Required autoclave tests: how are they performed?
1) Vacuum test
It tests air tightness inside the sterilisation chamber.
It is a very simple and self-diagnostic test aimed at ensuring that during the work cycle, there is no air leaking through the chamber seals (gaskets and valves).
The machine self-runs this test by selecting the special icon on the display
- with a cold chamber
- before starting the day's work
The result must be printed and filed, signed by the tester.
2) Bowie Dick test
It tests the ability to remove all the air from the chamber and the ability of steam to penetrate porous bodies (gowns, surgical drapes, etc.). The Bowie Dick test is highly sensitive.
Method:
- Place the standardized test sheet pack into the chamber
- Select the corresponding icon on the display
- Start the cycle
- Remove the test pack and read the test sheet
- A colour change over the whole sheet indicates that the test has been successfully passed
- File the strip with the cycle printout and the assistant's signature
3. Helix test
It tests the steam ability to penetrate hollow bodies.
It is a physical test performed with a 150 cm hollow tube wound in a spiral with a small hole at the end to let steam through. The opposite end is provided with a special housing for a sterility indicator strip.
Method:
- Insert the test strip into the slot of the special housing
- Place the test into the empty chamber after performing the Vacuum test
- Select the icon on the display to start the cycle
- At the end of the cycle, check for colour change all over the indicator strip
- File the strip with the cycle printout and the assistant's signature
Autoclave maintenance: a few tips
In conclusion, here are four things to do to keep your autoclave in good working order over time and ensure the safety of the sterilization process:
- Clean any impurities off the chamber walls with absorbent paper
- Monitor all reminders on the display and ask an authorised technician for advice
- Empty the tanks regularly and before idle periods
- Remember to have routine maintenance carried out by authorised technicians
