Degassing of demijohns

[iVivid]

I've got the vacuum pump thats like a brake bleeder not a vacuvin. I've never used it on my 5l demijohns as the glass seems thinner that normal carboys (I mean the 5 litre ones that come with the lid with a rubber seal attached and the little circle handle). Would it be safe to pull a vacuum on these ones? On the thick glass ones I pull 25Hg but don't know what would be safe in the little ones. Any ideas?

 

[vacuumpumpman]

I personally recommend not pulling a vacuum on a carboy that you know is fragile - it is just not worth it.
There are ways to transfer into them but not just to degass under vacuum