Sterilization - Position of Packets

Dear All,

Lately we came across an interesting issue in our team. We were trying to establish what is the correct way to place packets into the sterilizer for sterilization cycle: is it paper side up or foil side up?
We had a discussion and there were some arguments to back both ways, so which one is correct? Literature links will be appreciated 

Hi Dosia,

I actually try to avoid laying the packs flat (horizontally) because this can cause wet packs (this can cause re-contamination): condensate can built up (mostly on the foil side) and can not drip off properly. I usually put my packs vertically inside the autoclave to avoid this.


This is one of the most common discussion. Placing all the packs horizontally is one solution.

The best way is to place in such a way that each pack can have certain space whereby steam can enter though the paper side ,and the plastic side does not touch other pack hindering entry of steam and/or expelling of entrapped air during pre-vacuum phase.

The best way to find a right solution during cycle development and also using/designing proper trolleys with suitable separators where packs do not touch each other or avoiding irregular stacking.

The basic idea is to expel all entrapped air from deepest pockets and ensure entry of steam during ramp-up phases to enable entry of steam whereby air can be displaced with relative ease.

There is no straight forward solution for this because the items in each pack may be same or different. It should be properly developed during cycle development and proved during PQ and this should be used during production.

Source: LinkedIn Group

Be aware that orientation is considered critical in autoclave cycles. If you do qualification with all the packets verticle, then all loads run after than MUST also be verticle. If they qualified horizontal, then all the packets run after than must also be horizontal.

I would do a mixed load with packets going all different directions, and each run change the location of the packets which are verticle, which are horizontal etc. That way you can qualify that the orientation and location won’t affect pass/fail of the sterilization cycle. That way you have full flexibility, and will show that no matter who runs the autoclave or the orientation, the sterilization will be sufficient.

My choice would be paper down. This orientation should provide better draining of condensate. If paper is side up, condansate would be trapped in the bag.

Source LinkedIn Group

The manufacturer’s of these say the answer is neither. Place the packets on edge! It’s half right / half wrong regardless.

Source: LinkedIn Group

We can do a small heat penetration study to see what impact upside/downside and edge brings upon then choose the best , may be time taking but will be a solution.

Source: LinkedIn Group

Preferably it should be kept vertical rather keeping on plat form to reach the steam penetration. if it is not possible, better create some space both the sides . We can you purported trolleys to keep these type of items.

Source: LinkedIn Group