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-   -   Bad first experience with pasteurizing (http://www.homebrewtalk.com/f32/bad-first-experience-pasteurizing-277643/)

twgardner2 10-30-2011 11:09 AM

Bad first experience with pasteurizing
 
So I just finished my first cider and I was really excited about the sticky on pasteurizing my cider to get a slightly-sweet, carbonated final product. I followed the procedure and took plenty of safety precautions, but had a pretty harrowing experience.

I had one bottle explode (not just the cap popping off, I mean explode) in the pot while resting in the hot water. I assure you I heated the water to (just below) 190F and turned the heat off before inserting the bottles. The bottle exploded after about 7 min.

Luckily, most everything was contained in the pot, but after the first explosion, stepped up my safety precautions. I put a second pair of glasses on and I draped a small carpet over my entire body when approaching the stove - I must have looked pretty ridiculous!

The second explosion occurred, strangely enough, after I had removed the bottles from the heat and let them sit and cool. I am a nuclear engineer, so I've had plenty of training on heat stress to materials. I didn't dunk the bottles in cold water or anything. They were just sitting there and had been cooling for about 10 min. I had walked across the room and my SWMBO came around the corner. I told her one bottle had exploded in the pot and - right on queue - a bottle sitting on the counter BLOWS UP! Needless to say, she wasn't too happy.

So, I think I know why this happened. The bottles I'm referring to are Italian 1L glass water bottles. They aren't too thick and have probably been around for a while. I will no longer be bottling cider in this type of bottle. I think the larger bottle is more susceptible to thermal stress and internal pressure. Has anyone else experienced this? Am I safe to try my 12oz bottles? I've read through the sticky and some folks say they use 160F for 20 min. I think I will go that route.

Any thoughts?

Walking_Target 10-30-2011 11:12 AM

Those bottles aren't meant to deal with much in the way of pressure, a glass beer bottle is far better designed.

you could also switch to using champaigne bottles. they are made to handle much higher pressures than beer.

mr_goodwrench 10-30-2011 12:55 PM

I had one bottle bomb when I pasteurized my last batch of cider. I bottled the batch in mostly 12 oz bottles and 2 'bombers'. Oddly enough, it was a bomber that became the bottle bomb. I had pasteurized all of the 12 ozers and left the bombers for last. I had pulled the m out of the pot and set them on the stove top to cool as I had run out of room on the towel that the smaller bottles were cooling on on the counter. I walked into the other room and was talking to SWMBO when the thing went off. It didn't bother her too much since she didn't have to clean it up...

madbaldman 10-31-2011 10:28 PM

Quote:

Originally Posted by twgardner2 (Post 3438506)

The second explosion occurred, strangely enough, after I had removed the bottles from the heat and let them sit and cool. I am a nuclear engineer, so I've had plenty of training on heat stress to materials. I didn't dunk the bottles in cold water or anything.

Any thoughts?

In a nuclear reactor pressure vessel, cool down rate is more limiting than heat up rate. Why? Because during cool down both pressure and thermal stresses are tensile on the inside wall of the vessel. Cool down produces a greater total stress (on the inside wall) than any point during heat up (where the thermal stress on the inside wall is compressive and mitigates pressure stress).

twgardner2 10-31-2011 11:13 PM

Quote:

Originally Posted by madbaldman (Post 3442875)
In a nuclear reactor pressure vessel, cool down rate is more limiting than heat up rate. Why? Because during cool down both pressure and thermal stresses are tensile on the inside wall of the vessel. Cool down produces a greater total stress (on the inside wall) than any point during heat up (where the thermal stress on the inside wall is compressive and mitigates pressure stress).

True, that is why I didn't apply any cold water to aid in cooldown. But I got a really great demonstration of brittle fracture. It was definitely sudden AND catastrophic failure. I guess I was in violation of my operator's curves. :drunk:

madbaldman 10-31-2011 11:27 PM

I suspect with glass, you're always operating outside your BFPL curves. That's why pasteurizing is only for men of steel like us. ISOLATE THE PRESSURIZER! MAN THE CHARGE/DISCHARGE STATION!!! ;)


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