hist-brewing: Possible safety issue regarding whole hops added to primary before high krauesen

Bill Velek billvelek at alltel.net
Mon Aug 25 13:06:55 PDT 2008

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
My other sites:  www.velek.com ~ www.2plus2is4.com ~ www.grow-hops.com

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