Off grid people ill-prepared

[42OhmsPA]

Skip to 3:40

 

[Warpspeed]

That glass jar probably imploded from sheer fright when it saw that bloody great axe coming down.

 

[MurphyGuy]

Wonder how much vacuum you can pull on a glass jar before it becomes a hazard?

I have hundreds of them sitting down at whatever max vacuum that air conditioning service pump can pull.. I have never had one break.. About 2% will eventually leak air through a bad seal, but never a break.

Even dropped one on the basement carpet once..

 

[klystron]

I have hundreds of them sitting down at whatever max vacuum that air conditioning service pump can pull.. I have never had one break.. About 2% will eventually leak air through a bad seal, but never a break.

Even dropped one on the basement carpet once..

No surprise there. Regardless of how good the vacuum pump is, the jar will never see much more than about 15 psi pressure difference unless you submerge them at significant depth. FWIW, an HVAC service pump should be able to achieve less than 200 microns vacuum once outgassing of any contents ceases.

But, the discussion reminded me of the Price Rupert's Drop for some reason and if you haven't heard of it, it's a pretty neat demonstration of creating stresses in glass and what happens when they are released.

 

[MurphyGuy]

No surprise there. Regardless of how good the vacuum pump is, the jar will never see much more than about 15 psi pressure difference unless you submerge them at significant depth. FWIW, an HVAC service pump should be able to achieve less than 200 microns vacuum once outgassing of any contents ceases.

But, the discussion reminded me of the Price Rupert's Drop for some reason and if you haven't heard of it, it's a pretty neat demonstration of creating stresses in glass and what happens when they are released.

LOL.. Yea, I've seen them shoot bullets at those drops, break them underwater, and the slow-mo guys on youtube have filmed them up in the 150,000 (or was it 1.5 million?) frames/second range to watch them explode.

If I recall, the shock wave going through them is supersonic... which is kind of crazy... Usually takes a controlled burn of a low explosive, or the detonation of a high explosive to achieve those speeds.
If someone had asked me how fast I thought the Rupert's Drop shattered, no way would I have thought it to be faster than sound..

My freeze dryer gets to 190 microns when the food is done.. I don't think a normal air conditioning vacuum pump goes that low.. It probably could (maybe?), but I doubt standard practice is to allow it to run for that long.

When I vacuum a canning jar down, I usually let it run for about 90 seconds on a 1qt jar.. best guess is its probably around 1500 microns, which is still probably removing 5 times more oxygen than an oxygen absorber ever could...

 

[klystron]

My freeze dryer gets to 190 microns when the food is done.. I don't think a normal air conditioning vacuum pump goes that low.. It probably could (maybe?), but I doubt standard practice is to allow it to run for that long.

Here you go from standard practice for HVAC...

After the second standing test, allow the vacuum pump to run until the system is preferably below 200 microns. (With a good pump 50-100 microns is easily achievable.) Isolate the vacuum rig with the core tools and allow the system to stand for 15 to 30 minutes. If the micron level does not rise above 500 microns the evacuation is complete. If the pressure rises above 500, open the core tools again and allow the evacuation to continue.

 

[SYKSolar]

Yep.

I have a good friend with a 7,000 square foot home that sent me a link to some off brand solar generator he saw on Fox News or something. He was all excited he would have backup power for the house. I was like, sure, you could charge your many kids phones??

He thought air conditioning was on the table…

I was in that mentality when I first wanted to do a DIY Solar and I thought 600W or 1000W solar panels would be able to do wonders. So I bought 2 x 100 SP with a 30A Charge Controller. They were simply kept in the storage.
Then I bought 2x320W SP, a 3KW Growatt Inverter and EGC 5.12 KH Battery and I never saw the battery was charging. Later, I bought another 4 x 320W SP and it works but still under power. Whenever, I pluged a dryer and pushed the start button, the battery went into alarm mode! Lesson learned!

 

[MurphyGuy]

Here you go from standard practice for HVAC...

After the second standing test, allow the vacuum pump to run until the system is preferably below 200 microns. (With a good pump 50-100 microns is easily achievable.) Isolate the vacuum rig with the core tools and allow the system to stand for 15 to 30 minutes. If the micron level does not rise above 500 microns the evacuation is complete. If the pressure rises above 500, open the core tools again and allow the evacuation to continue.

Interesting.. I didn't think the evacuation would require them to go that low on a refrigeration system. Thanks for the post..