WFHSS Questions and Answers - Question Q01202

Does anybody have already challenged, on a regular basis, the equilibration time during the sterilization cycle (porous or liquid,...) as recommended in the EN 285 and HTM2010.
What kind of load are we supposed to use during this test?
Is it easy to comply with the requirements?

Thanks for your helps

Dear Tomas,

HTM2010 criterion for equilibration time:

13.14 The test should be considered satisfactory if the following requirements are met:........

c) the equilibration time determined from the measured temperatures
does not exceed 15 seconds for chambers up to 800 l and 30 seconds for larger chambers;

Regards
Ted Baker
www.isopharm-sentry.com

Tomas,

The test is really significant for porous loads:

HTM2010 states:

The load is made up of a standard test pack (see paragraph 7.27) and
additional folded sheets designed to represent the maximum mass of textiles which may be processed in the sterilizer. Each sheet should contain at least 50% m/m of cotton fibre and have a surface density of approximately 200 g m-2. They should be washed and aired as for the standard test pack (see paragraphs 7.30-31). After airing, the sheets should be folded to approximately 25 cm x
50 cm and laid one on top of the other to form stacks of mass 7.5 0.5 kg.

7.29 The test pack is composed of plain cotton sheets complying with BS5815:
Part 1, each bleached to a good white and having an approximate size of 90 cm x 120 cm. The number of threads per centimetre in the warp should be 30 – 6 and in the weft 27 ± 5.
7.30 The sheets should be washed but not subjected to any conditioning agent. (Conditioning agents may affect the characteristics of the fabric and may contain volatile substances which will contribute to the non-condensable gases in the chamber.)
7.31 The sheets should be dried and then aired for at least one hour at a temperature of 15-25 C and a relative humidity of 30-70%. Failure to observe this protocol can result in the test giving a pass result when it should have been a failure. Sheets which have become excessively dehydrated may cause superheating in the pack, which might also produce misleading results.
7.32 After airing, the sheets should be folded to approximately 22 cm x 30 cm and stacked to a height of approximately 25 cm. After being compressed by hand, the pack should be wrapped in similar fabric and then secured with tape no more than 25 mm wide. The total weight of the pack should be 7.0 ± 0.7 kg.
The sheets will become compressed after the pack has been used. If the weight of sheets needed to form a stack 25 cm high exceeds 7.7 kg, the sheets should be discarded.
7.33 Packs which are not used within one hour of preparation may be stored, providing the environmental conditions are maintained within those specified above for airing.
7.34 Non-standard test packs made of different materials (including huckaback towels TL5 or TL6 complying with BS1781) and of different sizes and weights may be used, provided they comply with BS7720. These packs may also be useful for small chambers (see paragraph 7.35).
7.35 The standard test pack should not be used where the usable chamber space is less than five times the volume of the pack. In these cases a smaller version of the pack may be constructed. This should be of cubic form with a volume about one-fifth of the usable chamber space, and made of similar materials to the standard test pack.

Such Standard Test Packs are avilable from Isopharm-Sentry Ltd
www.isopharm-sentry.com (use search for Standard Test Pack Wrap)

Regards
Ted Baker

Dear Tomas,
As Ted told you the equilibiration time determined is for porous loads and not for liquid loads, are the same in the EN 285:

The equilibration time determined from the measured temperatures
does not exceed 15 seconds for chambers up to 800 l and 30 seconds for larger chambers.

If you have problems I suggest you have a look at the air removal (pre-vacuum) phase and heating phase or the load itself.

Chris

Dear Tomas,

this criteria is verified during typical validation. It can be performed on empty chamber and loaded chambers. A number of thermocouples are placed througout the chamber or in the load to be validated. Equilibration is then verified when the thermocouple ajaccent to the PT100 in the drain reaches the sterilisation temperature setpoint. All other thermocouples should then reach the sterilisation temperature setpoint after 15sec. for a chamber smaller then 800L and 30 seconds for a chamber bigger than 800L.

This is one of the 5 important parameters to be checked.

Best regards,
Marc.

Dear,
"During validation of the sterilization process the eqilibration time is taken into account. EN 285/EN 554 states that with every load sterilization conditions should be met. In other words: you should try to determine what your worst case load is and regularly validate that load, where all criteria have to comply with the norm. Whether it is easy to comply with the requiremens depends on the sterilizer in combination with the load, wrapping and process. With normal hospital loads it normally should not be a problem to fulfill the requirements."
The redaction