Here's an overview of our coin crushing system at the lab.
https://www.youtube.com/watch?v=C_5myKEarfg
The blast chamber is B4 stainless filled with sand. Between the chamber
walls and the outer walls the whole box is filled with reinforced concrete.
We have to replace the sand after a few dozen shots, as it pulverizes down
to the consistency of talcum powder.
Humans are not allowed in the bunker with it when it goes off.
On Mon, Jun 18, 2018 at 2:57 PM, Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hi Steve,
>
> Sounds like good plan.
>
> Consider building a relatively large volume blast shield around the region
> of activity if you plan to run at higher energy levels. The internal volume
> of mine is about 0.4 cubic feet, but I never run it above 8 kJ. I initially
> used 1/2" Lexan sheet on my blast shield, but I quickly discovered that I
> needed to reinforce it with steel in the regions directly impacted by coil
> fragments. Prior to this, I began fracturing the Lexan at 8500 joules from
> wire fragments and the shock wave when the work coil exploded.
>
> I've been using abrasion-resistant (AR400) steel on the inside surfaces of
> the blast shield. No problems after over 7,000 shots. Another coin
> shrinking experimenter uses an old safe for his blast shield. And, many
> years ago, some Texas coin shrinkers used a large diameter 1/2
> thick steel tube (the base of a large outdoor sign), topped by a
> comparably thick steel plate that was then weighed down with several
> hundred pounds of sandbags. However, higher-energy shots (over 20 kJ) still
> lifted the top plate sufficiently to allow fragments to escape into the
> lab. 48 kJ packs the energy equivalent of ~35,400 foot-pounds or energy,
> and exploding coil fragments have been measured at over Mach 4.4.
>
> Plan accordingly.
>
> Bert
>
>
> Steve White wrote:
>
>> I originally tried to get information from Aerovox about my unit. They
>> said that they had no record of it because it was made in 1992 (I presume
>> from the serial number). I assumed that they would have records of all such
>> huge capacitors but I guess not.
>>
>> I am think of buying another one of the Aerovox capacitors (PM-series,
>> 102 uF, 22 KV) and connecting it in parallel with the one that I already
>> have. This would give me a combined maximum energy of 48 KJ for mayhem. My
>> primary reason for doing this though is to get the same energy by charging
>> to a lower voltage to minimize VR and thus extend capacitor life. The same
>> E-Bay seller that I bought my current unit from is offering another one.
>> Any thoughts?
>>
>> Steve
>>
>> ----- Original Message -----
>> From: "Bert Hickman" <bert@xxxxxxxxxxxxxxxxxxxxx>
>> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
>> Sent: Monday, June 18, 2018 9:51:22 AM
>> Subject: Re: [TCML] Need Energy Discharge Capacitor Information
>>
>> Hi Chris,
>>
>> These are also heavy-duty energy discharge caps, using a kraft
>> paper-foil dielectric system. The Aerovox PM series are all rated at 20%
>> voltage reversal, and no self-healing.
>>
>> The low capacitance and dielectric system for your caps limit their use
>> to low pulse-rate, very high-voltage applications, such as flash X-ray,
>> Marx generators, exploding wire, or rock fragmentation work. The
>> dielectric system will be fairly lossy for lower-voltage oscillatory
>> applications, and the stored energy is limited for coin shrinking since
>> work-coil flashover limits maximum cap voltage to 20-25 kV.
>>
>> You might be able to get more information by directly contacting the
>> folks at Aerovox. Unfortunately, many of their energy discharge caps are
>> custom designs. This often binds Aerovox to non-disclosure agreements
>> with their customers, preventing them from releasing even basic
>> capacitor specs...
>>
>> Best wishes,
>>
>> Bert
>>
>> Chris Reeland wrote:
>>
>>> Okay, to get back on track to the topic, I have been following this with
>>> interest.
>>> I also have a pair of energy discharge caps that I have picked up last
>>> year
>>> for a future project that I can't find any info either. Any info would be
>>> appreciated.
>>> Aerovox:
>>> PM104YW003D04
>>> 3.110 uF and 3.364 uF
>>> 100,000VDC
>>> 15K Joules
>>>
>>> They are in a stainless steel case.
>>>
>>> A couple of pictures also if I made a typo...
>>>
>>> https://photos.app.goo.gl/wPq4WEvYLuGbXKqM9
>>>
>>> https://photos.app.goo.gl/jTgwWWiTbqaEA9ph7
>>>
>>> https://photos.app.goo.gl/LHnuy85eBTaSZUP38
>>>
>>> Thanks,
>>> Chris
>>>
>>> Sent from my LG V20
>>> _______________________________________________
>>> Tesla mailing list
>>> Tesla@xxxxxxxxxxxxxxxxxx
>>> https://www.pupman.com/mailman/listinfo/tesla
>>>
>>>
>>>
>>>
>>
>>
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>>
>>
>>
>
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www.thegeekgroup.org
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