Can anyone who has experience with autoclaves help me with this one? When i run a cure, the vacuum pressure drops to the point of failure around the same point in the program which is roughly 45PSI external pressure and about 80c temp. Have run dummy cures with just pipes that passed, the valves have passed testing, and have run cures with bagged tools with material and without with same results. My gut feeling is that the bagging film has an inherent fault that is so tiny, the autoclave sensors are unable to pick it up as they pass the drop tests easily until the reoccurring specific point. What i am wondering as an alternative reason is that could the autoclave itself somehow be responsible? ie, is there somehow compressed air getting into the vac system causing the bag to lose pressure when the external pressure reaches a certain limit? Or is it as simple as a faulty bagging film? Has anyone had similar issues and what was the solution?, thanksz . I think it is worth mentioning that when the external pressure is flushed out, the vac pressure climbs again and then no leak is detected when re-tested…very strange!
I wish I could explain more, but no one around here knows the answer. WHen we are holding vacuum, and add pressure, the relative vacuum indicated drops slightly. Shutting off vacuum to vent will not only give a 0" reading, but sometimes show pressure. It is confusing, but I have accepted it as “wth, they say it does that, so I’ll accept it”
Are you holding constant vacuum?
Have you did a post inspection of the bag? Go near the limit of the bagging material, and maybe if there is a hole, the heat will melt the hole larger. Else, inspect everything VERY well before putting the part in. You can have a bad bag roll, either from shipping, storing, or someone accidentally hitting it with their knife. Does your part have sharp edges? Watch out for that as well when bagging. Are you bridging the bag?
to add to riff42: which bag and tape do you use? My suspicion is in bag, in application of the bag, in the tape + application of the tape, and in the hose connector.
I think we are on the same page regarding the bagging film being the likely cause but i just wanted to know if anyone else could tell me something i did not know. The bag is checked extremely well before and after cure and passes both times. The tool does not have any cutting edges and has been checked for splinters. There is no bridging of the bag either. The tacky tape is normal I believe. Need to get a handle on it before it becomes a major issue so doing a process of elimination at the minute and it points to the bagging film.
When the clave is at pressure are the vac lines open to the atmosphere or shut off? If there is a small leak and the lines are shut off there will be an increase bag pressure, where as if the lines are open the air can bleed out. Also as the material cures there are gases released which can build up pressure.
We have had failures in the past when the vac lines are shut off and there is a part cooking.
The vac lines currently were open but if you mean were they vented when you say shut off then no would be the answer this time. Regarding gases, even the dummy cures with bagged tools but no material was the same result. I have picked up on Hermans point regarding the sealant tape. Although it is still within its shelf-life, the backing tape keeps falling away which is unusual in itself so I am wondering whether it may be below standard?
Which tape is it? Some tapes cure somewhat, to make them more easy to remove. If the tape has been heated by accident you might run into trouble.
By coincidence I just had a batch of tape go bad. (2 pallets…) Perhaps sun storms had a part in it. 
Don’t release coat the mold where you put the tacky tape!!!
You can have faulty connectors, hoses, tool, clave as well :-/
It looks like all the fingers point at the tape being a partly bad batch folks, everything else has passed trials so the have someon looking into the backing paper release as this just falls off and doesnt help. Thank you to all who took the time and trouble to help, till next time?:idea: