I am having the following question for a while now: does a combination of sterilizing liquid load and porous load in one cycle exist?
Example: how would you sterilize a bottle filled with liquid (2L) with on top a sealed bottle top with two tube outlets (see sketch below):
one outlet is to allow venting of the head space during the cycle. The tube is not submerged into the liquid. The tube sticks out 10 cm at the outside of the bottle. The end of the tube has and air filter.
one outlet is submerged into the liquid (at the bottom of the bottle). The tube one the outside is 1,5 m long, and is clamped close to the bottle top to avoid any of the liquid to exit the bottle during the sterilization process. The end of the tube has an air filter.
This would require a combination of liquid load and porous load cycle: not too much vacuum to avoid overboiling, though enough to remove air from the dead end (see sketch).
Also a combination of liquid and porous bioindicators will be needed (first to monitor inside the liquid, others to be placed at the hard to sterilize parts of the tube).
Lastly there is a closed space which will be hard to sterilize: air is trapped inside and cannot be removed.
Considering all the above, is it a good idea to sterilize this load as one, or are such load usually split up?
Liquid loads typically don’t have any vacuum because of boilover issues. They will have a purge cycle instead, in which steam enters the chamber at the same time that the chamber is vented (thus the steam and air sweep through and out the chamber together)
The dead end tube length is a pretty big possible source of contamination. Is there another way you can set this up? Can you unclamp the tube, but leave the clamp there (just unfastened) and rely on the vent filter to vent the air. Can you shorten the tube (1.5 meters is mighty long, and would be difficult by itself in a liquid load, even if it was vented on both sides). If you need a long tube, can you put a sanitary connector super close to the bottle, and the other side of the sanitary connector on the rest of the 1.5 meter tube? After sterilization you could connect the tubes to make a 1.5 m tube.
Could you employ sanitary connectors? Could you sterile filter, or e-beam sterilize (thus no need to evacuate the air out). Could you do sterile assembly (in an isolator or hood with proper gowning).
One option would be to sterilize each part, then do a “sterile assembly”. You would have to get a sterile hood or chamber to assemble this together, and follow sterile gowning techniques. You might use a sterile chamber (using VHP or other sterilant) as well.
It is very hard to sterilize in one cycle. Porous load in this case is very demanding - 1.5m tube, so you will probably have a lot of vacuum cycles before sterilization phase and that cycle configuration is not appropriate for liquid container load!
On the other hand, 2L container will have long heating time, so you should combine between lot of vacuum cycle to get equilibration time less than 30sec and heating of 2L container which can take too long…