# Pressure pot to vacuum pot?



## Dominic Greco (Jul 8, 2006)

Boy, it seems like forever since I've been back here! Having a one year old around the house sure eats up your time! 

When nap time rolls around I sprint to the shop to see if I can squeeze in some turning time or work on a shop built tool. I just spent the last day assembling my "pickle jar" vacuum chamber only to find that the quick connects I used are the wrong size for the compressed air hose that leads to my vacuum pump! Oh well,...looks like I take another trip to Lowes.

I was wondering if anyone has given this idea a try. We've all seen the HF Pressure post (and now they're on sale for 1//2 price). I was wondering if anyone has used them as a "vacuum chamber" for stabilizing pen blanks.

The reason I bring this up is that I've been thinking of that the glass jar imploding when under vacuum. I'm one clumsy cuss. I think the only reason I have a trash can in the shop is to have something to trip over.  I can just picture myself knocking this rig over just when it's reached 25" hg.

Anyway, the imploding glass jar gives me the willies. I could wrap it in a layer of clear shrink wrap. If it did implode, the wrap should contain the debris. I could also build a wooden cradle to hold the jar stable. But I may be over complicating this a bit. I guess it's just the engineer in me...

Maybe I'm making a big deal out of nothing. Maybe not...

You tell me.


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## JimGo (Jul 8, 2006)

Others have suggested either putting the pickle jar in the pressure pot (just prop the lid open), or wrapping the jar in duct tape (stronger than the plastic wrap).


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## BUGSY (Jul 8, 2006)

pickle jar or glass for that matter gives me the shakes...tried it ..felt uncomfortable..bought hf pressure pot and feel a lot better about being around it...bugsy


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## Mudder (Jul 9, 2006)

> _Originally posted by BUGSY_
> <br />pickle jar or glass for that matter gives me the shakes...tried it ..felt uncomfortable..bought hf pressure pot and feel a lot better about being around it...bugsy



The pickle jar concept has been argued before.

It's all comes down to personal preference. If you do not feel safe with a pickle jar then someone suggested putting it in a 5 gallon bucket, or wrapping it in duct tape. I'm not sure how much vacuum in used at the cannery but a pickle jar is made for vacuum use.
Iâ€™m not a scientist and I donâ€™t know if there is any stress factor for repeated usage but I will say that plain old pickle jars are used in our lab at work along with our super expensive bell jars. We pull 28â€ of vacuum using deep cycle pumps and leave the vessels under vacuum for days on end. (some of the oils we use take weeks to penetrate the bearings and we release and redraw the vacuum twice a day)

Vacuum is nothing more than the absence of atmosphere, therefore there is more pressure on the outside of the jar than on the inside and if there was a catastrophic failure the jar would implode (collapse into itself). I have seen it happen with a pickle jar and I have seen it happen with "bell jars" that are specifically made for vacuum. What happens is that you hear a "pop" and then a "whoosh" and by the time you turn around you see a pile of glass on the bench. We do use what is called an "implosion guard" which is nothing more than a screen mesh tube that is about 6" larger in diameter and sits over the bell jar. Of every implosion that I have seen (probably 7 or 8) the glass has never made it to the implosion guard 3 inches away.

Again, Use what you feel comfortable with. Wrap the jar in Duct tape, set it into a 5-gallon bucket. go to the hardware store and get some 1/4 inch screen used for rabbit coups or use a pressure pot. I will tell you from more that 10 years experience of seeing vacuum pots and bell jars used every working day that I have never seen a vessel under vacuum explode.


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## Dominic Greco (Jul 9, 2006)

Thanks for all the replys. I think Mudder's screen suggestion is a good way to go. Once I get off my butt, go to Lowes and get the right size fitting, I may also pick up some rabbit cage screen.


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## JimGo (Jul 9, 2006)

Mudder,
Very good point.  My only concern was how far out any imploding pieces that ricochet off of each other might fly.  If you've never seen them go more than 6", then that's not so bad, except in a shop the size of mine where it's hard NOT to be 6" from the pickle jar!  []


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