On Saturday Barron and I did a simple test on the Boomerite packaging. It was hypothesized that the heat from heat shrinking the plastic wrap was causing evaporation of the ethylene glycol. We put a thermocouple temperature sensor just inside the cardboard box and applied the heat shrink plastic bag as normal. There was less than 1 degree F rise in temperature.
We applied heat until the plastic melted. The temperature just barely raised. That means it’s not the heat.
There are two remaining hypotheses:
- The additional thickness of the shrink wrap caused compression of the Boomerite when we squeezed the same number of boxes into the crates. I’ll have to order some more boxes and heat shrink bags to test this hypothesis.
- The slight change in mixing order changed things. Last year when we had exceptional good detonation rates someone, not me, had the bright idea of mixing the potassium chlorate with the secret ingredient before mixing in the ammonium nitrate and ethylene glycol. They told me they were doing it and I had sort of a nagging feeling about there being a reason not to do that but my brain wasn’t working well at the time* and I okayed it. A day or two after the event I figured it out. They were, in essence, making “flash powder”. The EG goes in first to eliminate the dust and static electricity during the mixing process.
It will probably be the middle of June when I go back to Idaho to do the tests.
*Just two weeks before I had served papers for legal separation on my wife of 35+ years. This year I was feeling much better and one guy told me that I looked terrible the year before and that this year I “looked ten years younger”. He also asked, “Is the new woman you are with (Barb L.) just as smart as you? I confirmed his suspicion that she is a smart cookie.
We also did the mixing by eye, mostly. ISTR the mix times being shorter because of that. Maybe the extra mix time made it less fluffy or something?
I thought we also poured EG in to the AN while it was being mixed, and this time it looked like we were pouring everything in without the mixer being active.
I certainly noticed a difference in texture. Before, we’d have maybe some of the solidish caked fine ground stuff in the bottom, slightly moist, like we did on the mixing tool. This time, we sometimes had a fair amount of ethylene glycol in the bottom and not as much of the powder mixed in. It also seemed a bit dryer overall.
Maybe we need to refresh the lines on the EG measuring cup and make sure they are accurate? And/or do the EG/AN mix first and then add the rest?
Thank you Tim.
I think I need to have instructions at each station and insist they are followed.
I didn’t do any mixing this year; worked at one end or the line or the other, not the middle. I did notice that we have a variety of people doing it, and it’s quite possible that they were not all doing every step exactly the same as in the past. I’d say that VERY explicit understanding of what step, in what order, and documented at each station, would be appropriate, to avoid problematic minor but significant variations in procedure. Something as “small” as “pour in the EG, turn on mixer for 90 seconds on 4” vs “turn on mixer for 90 seconds on 4, pour in EG while it turns” may may a bit more important than it seems.