Failure on a smaller scale

[3DDave]

https://www.reddit.com/r/Wellthatsucks/comments/dx1r1e/nutribullet_living_up_to_its_name/

Some of the comments on that posting suggest that the system has no way to deal with heat input via the blender. Which does harken back to the origin of understanding of heat in the observation that it wasn't stored in the material by way of observing the boring of cannon, where heat flowed out as long as the boring operation continued. So in all these years of science and engineering it appears that someone was asleep in class for that part.

Still, it seems like a big oversight to build a pressure cooker bomb without a relief valve.

It also makes me very happy to have a conventional blender that makes a conventional mess when the lid is loose.

 

[JStephen]

When I was in college, I was out at my friend's uncle's farm for some varmint hunting. Somewhere on the property was the old junk heap and in that junk heap, an old pressure cooker. A big jumbo pressure cooker, presumably used for canning, maybe 5 gallon capacity? Anyway, the lid was stuck on. And stuck on GOOD. (Presumably, the vacuum relief failed and force it on.). Anyway, being industrious young men, we took a baggie, poked part of it down through the vent hole, then poured maybe an ounce of black powder in there, put a fuse in, set it down behind a creek bank, lit the fuse and dispersed. Foom! The lid went up in the air a few feet and it was open. Unfortunately, that also cracked the cooker itself, so it was still no good, but at least the lid was off.

When I got married, my grandmother-in-law got us a pressure cooker, and we used that quite a bit- eventually quit when we lost some of the seals or something of the sort.

 

[1503-44]

Are you sure it wasnt a still?

Yes. Black powder can be pretty hard on seals.

 

[IRstuff]

The Nutribullet, in particular, can't have a relief valve, since the container opening is what screws into the base of the blender, unlike any other blender, which typically is open at the top and bottom.

The Vitamix can actually boil its contents solely from the frictional heating of its blades; I didn't think the NutriBullet could do that, but it wouldn't surprise me, one way or the other. I'm guessing the user bypassed the momentary ON switch to be continuously ON, and then walked away and got the thing to boil its contents, so the answer is that the user abused the system, by defeating its momentary switch, which would have forced the user to hold the switch down, in which case they would have noticed it getting uncomfortably hot.

TTFN (ta ta for now)
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[LittleInch]

This looks like a nutibullet RX which is the big daddy at 1700W motor(!!)

https://www.amazon.co.uk/dp/B01M3115C2?ascsubtag=AwEAAAAAAAAAASwk&linkCode=gs4&tag=thewire04-21

The giveaway is that the plastic mug has a handle. The one buried in the ceiling would seem to be buried to a depth of 40-50mm and stopped only by the handle.

Must have been some bang.

Interesting video here

https://www.youtube.com/watch?v=aiy4kju0ubs

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IRstuff]

LI, thanks.

So the link does show a similar claim to being able to make soup in 7 minutes. According to Vitamix, it can "make steaming-hot soup in under 10 minutes"

But, unlike the Vitamix, this one has no ability to vent steam. Assuming similar capabilities, the user of this device left it on and unattended for well over 7 minutes, despite warnings in the manual. Apparently, the OPs link is not the only incident, and there are others that suffered injuries

https://www.goodhousekeeping.com/health/news/a46908/exploding-nutribullet-lawsuit/

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[LittleInch]

Also depends on how hot the liquid or contents were when they went in....

The instructions also say there is a "souper blaster" pitcher which has a vent, but I suspect this will be lost on many users who will use any pitcher they have available. Temp rise is quoted as 40-50C in 7 minutes so if you start at 50 C with an unvented pitcher...

Definitely sounds like a recipe for disaster.

https://images-eu.ssl-images-amazon.com/images/I/A1xUGkPsdZS.pdf

In retrospect the original picture which started this got lucky - a hole in the ceiling is a lot easier to repair than a hole in your head.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[3DDave]

Had they designed the housing to thread to the outside of the blending cap then the pressure would have a chance to bleed off as the plastic would expand and make a huge mess, but I bet they found that sealing that was problematic, so they changed it so that bleeding pressure was not possible.

Even so, it seems like the blending cap could have a deformable section that could balloon out under pressure and push on a switch to shut off the motor if the pressure was too high. They could also have a separate blending cap for the sealed cup that tripped a switch that only allowed blending for 30 seconds at a time with a 30 second lock-out.

Yikes on the injuries in that TV news program.

 

[IRstuff]

They could also have a separate blending cap

NutriBullet can't even manufacture a flat surface on those cups, so any sort of precision beyond that is probably beyond their capabilities. We bought a set of their standard cups for their standard Bullet, and my wife was complaining about it leaking, despite having a rubber seal. It turned out that the lip the seal goes against has a large dimple due to an asymmetry at the hinge, during the injection molding. It's tiny, but it results in leaks.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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