Lid from Fermenter Bucket Popped Off

[ZeeSniper]

Just for a bit of background...

I've brewed many good/decent batches of beer, but still consider myself a beginner. This has me a bit confused though, because I really didn't do much different and stayed as sanitary as I normally do, and yes I have a blow off tube.

The other morning I discovered the lid of my fermenting stout blew off, and spewed some krausen over the wall and side of the fermenter.

The only thing I did differently with this brew, was that I used an immersion chiller for the first time (made sure to sanitize first). This was actually probably the first brew that I actually got to the proper pitching temp (before was ~10 degrees F higher or so).

My questions are:

1) What could have caused this?
2) If it was semi open for ~2 hours, but still actively fermenting, how likely is it that it got infected?

 

[unionrdr]

We had that happen once on a batch of the wife's ale. The blow off clogged during initial fermentation. Too much co2,no placve to go...loud pop! Cleaned the tube & lid,re-sealed. You shoul be fine,what with all the co2 being produced.

 

[Gear101]

Spray everything with cleaner and put it back on, keep an eye on it for the next week or so. You should be fine.

 

[JesperX]

Did you use a different yeast this time or make a bigger starter? Also, The bigger the beer, the more vigorous the fermentation when you pitch the right amount of healthy yeast. Sounds like it just built up a good amount of pressure. I wouldn't worry too much about infection- when its fermenting that vigorously the krausen plus the positive pressure from the CO2 generation will protect the beer. Cover it back up and let it go.