Rootbeer (Bottled from Keg) Bottle bomb

Just as I was going to bed last night I heard shattering glass which I pinned to roommates dropping something, then it woke me up again at 3am. I went and checked what it was turned out it was my rootbeer bottles exploding! I know if you bottle condition these that they will explode if not refrigerated but these were bottled from a keg and never had any yeast introduced to it. I had the keg carbed to around 20psi. Everything bottled fine I left 1"-1.5" of head space in each bottle. I'm stunned, it hadn't even crossed my mind that these would be able to become bottle bombs. I even stored them all un-enclosed in my living room thank goodness no one was around when it happened.

Does anyone have any ideas why this may have happened? Was I wrong in thinking bottles from kegs won't explode?

Thanks all

It sounds like it was carbed up more than beer is, and that the bottles weren't capable of holding the higher carbonation of soda.

Beer is carbonated to 2.2-2.5 volumes of co2, typically, while soda is carbed to more like 4 volumes (or more).

Soda used to come in glass bottles when I was a kid- very solid, thick, heavy glass. Plastic is more common now, and holds more pressure than thin glass.

There's a local soda maker here that uses bottles very similar to (possibly identical to) beer bottles. They are nowhere near as heavy as the deposit bottles of old.

http://losttrailsoda.com/

I've never seen a glass bottle break from soda equilibrating to a pressure that's too high for the glass to handle. If you're using a counter-pressure filler, the pressure that it experiences during filling is higher than anything else it's going to see from the soda pressurizing headspace.

Depending on your sanitation and ingredients, they could very easily get wild yeasts fermenting in them.

The time between filling from the keg and capping the bottle it's open to the air and susceptible to contamination. You also need to be very careful with how well you're cleaning and sanitizing your bottles and your filler. Also take a look at what you're sanitizing with. I once used B-Brite as a cleanser and sanitizer because I was told that longer contact time was an effective sanitizer, even though it doesn't say that on the container. I had a higher incidence of those bottles starting to ferment and gushing than using a dedicated sanitizer, so I'll only use that as a cleanser from now on.

Farny is it possible your soda established spontaneous fermentation?