Possible safety issue regarding whole hops added to primary

What went wrong? Was this supposed to happen? Should I throw it out? What do I do now?

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Possible safety issue regarding whole hops added to primary

Postby billvelek » Mon Aug 25, 2008 4:09 pm

This involves one of my 'lazy brewer' techniques, but also possibly relates to a safety hazard when adding whole hops to a carboy prior to high krauesen. I'm posting this (but not 'cross' posting it) in many of the brewing groups and forums where I am a member because I can't remember where I've suggested my technique, and I also think this is important enough to warn other homebrewers about; I apologize for the inconvenience due to any redundancy you might experience.

About 20 or 30 batches ago, I got the hair-brained idea that instead of using a blow-off tube at the beginning of my primaries, I would use a sanitized drinking glass inverted over the neck of my carboy which sits in a tray. I reasoned that, even without a perfectly air-tight seal, the glass would still keep flys and other critters out, and allow gas and krauesen to escape, but yet be a whole lot easier than cleaning the krauesen from the inside of a blow-off tube. When krauesen drops after a day or two, I have always replaced the glass with an air lock. The glass did, however, permit blow-off to run down the sides of the carboy and into the tray, but they were easily cleaned during regular clean-up, so I didn't care. I never had an infection nor ever noticed any signs of oxidation (the positive pressure and blanket of CO2 during the active fermentation should prevent that). And for those just getting into brewing, a spare glass or small jar is a whole lot cheaper than buying about 3' of 1.25" diameter plastic tube. It worked great and was so easy and simple that I posted it as a suggested practice in many forums.

Today the thing blew up on me ... LITERALLY. It either blew up or the glass shattered when it hit the ceiling. I was sitting at my computer about 15 feet away when I heard a bang and the sound of pieces of glass hitting things, so I turned and looked at a column of foam about three or four feet tall which continued to get taller until the column finally reached my 8' ceiling and left a big wet spot on the spackle. It looked like when someone opens a bottle of champagne, but much bigger. The good news is that my carboy didn't explode, and falling glass didn't seem to break the top of it, as far as I can tell (I'll give it a good inspection when I clean it up later). The carboy is now less than half full ... <tears welling up in my eyes> ... but hopefully I'll still have at least some of the beer to salvage; I'll siphon to a secondary later, in case there are any bits of glass.

Now, I still believe that an inverted glass is ordinarily a good and safe technique, and I think I've figured out what went wrong this time. First, there obviously had to have been an "_air-tight_" seal, and one strong enough to prevent a momentary lifting of the glass a fraction of an inch to permit the carboy to burp. With constant seepage of blow-off to prevent any drying which might glue the glass to the carboy, how did the pressure rise so high? I think the answer is that I used hop plugs, which are like whole hops rather than pellets, and also that I decided to add the hops into the carboy. Normally I pour my wort from my kettle into a bucket for aeration, but I also use a strainer sitting on top to collect the hop cones which are then discarded. This time I had forgotten to sanitize the strainer, so I decided to just forget about it and let the hops go into the carboy; nothing seemed wrong with that, especially if the flavor and aroma hops might be able to contribute a bit more. I therefore suspect that the hops collected under the glass and finally packed inside of the neck of the carboy because they couldn't get out. As pressure increased, the hop cones probably packed tighter and tighter until the hops -- rather than the glass -- caused an airtight seal. I think that it was this plug of hops that finally broke loose and propelled the glass to the ceiling. That is the only logical explanation that makes sense to me. The glass I used seems thicker than the glass of a carboy, so if pressure were high enough to explode the glass, I think the carboy would have exploded first, although maybe the radius of the glass is a factor. By the way, to give you an idea of how heavy-duty the glass was, it was only 4" tall, 3" diameter at top, 2.5" diameter at bottom, but weighed 9.6 ounces; I just measured one like it. I'm sure that the glass either exploded or shattered on the ceiling because if it had not broken until hitting the floor, I would not have expected the base of the glass and other pieces to be on top of my table like they were.

The bottom line is that I'm wondering if the same thing could have happened with a blow-off tube, which might offer enough resistance to whole hops so as to cause them to begin to pack together; maybe the real lesson here is to not add whole hops to your fermenter until after high krauesen is over. Any thoughts?


Bill Velek -- portal to my "HOMEBREWING" sites: www.tinyurl.com/29zr8r
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