I made a permanent blow-off tube / gallon jug setup years ago that locks into the top of the any of my Big Mouth Fermenters for the inevitable Volcano's. It is standing by. Since my specific gravity is so low now there is not much chance of a blow up. That usually happens within 24-48 hours of the start of the fermentation along with a stressed yeast making the SO2. If you touch the top of the must with a spoon that is usually when it erupts like a Volcano. I don't really "Rack" this first fermentation I use a Mesh Filter Bag and a 7.9 Gallon Fermentation bucket. I first sanitize everything then clamp the filter bag over the rim of the bucket and pour the contents of the Primary into the filter. It foams up but not enough to cause a problem. More importantly it introduces lots of oxygen to the must going into the Secondary Fermenter since they are air locked and never opened till Stabilizing & Back Sweetening time.