Re: vacuum and poly capacitor (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 15 Sep 2007 21:28:45 -0700
From: Frank <fxrays@xxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: vacuum and poly capacitor (fwd)

An easy way to fill a cap is as follows:

1) Get a jar at least a quart in size, it needs to be heavy glass. 
Canning jars work good for this, use small mouth ones.
2) Make sure you have a good solid lid or heavy rubber cork that will 
seal the top of the jar.
3) Punch out 2 holes for the tubing, make sure the holes are slightly 
undersized so it is a tight fit. Pass  2 tubes thru the lid/ cork, 
one is just below the bottom of the lid/ cork and the other tube goes 
all the way to the bottom of the jar.
Fill the jar about 1/4 full of oil.
4) Fill the cap with oil and gently tap it, this will dislodge some 
of the air bubbles
5) Connect the cap to the jar on the dip tube side, IE the tube that 
goes to the bottom of the jar.
6) Connect the short tube to the vacuum pump. Make sure you have a 
needle valve in series with the pump, close the valve

Start the pump and slowly open the valve. Use the valve to control 
the foaming in the jar. IE if the foam gets near the top, close the valve.

A good, cheap source for some hosing and connections is Harbor 
Freight or Ebay to purchase an AC manifold with at least 3 hoses. 
Then go to an appliance shop and buy some refrigeration fittings that 
are a match to the refer hoses to 1/8" NPT male and some brass caps 
for the fittings. Total cost will be around $20-30.
Put the fittings on the pump, cap and both jar connections. You will 
need the connections to be all 1/8" NPT. The pump, jar and cap will 
be 1/8" NPT female.
Remove one hose from the manifold and connect to the cap and jar as 
mentioned above. Take the hose off the side that has the high 
pressure gauge and make sure the valve is closed on that side.

Connect the center hose to the vacuum pump.
Connect the remaining hose to the jar on the short tube.

These AC manifolds and hoses are designed for vacuum pumping and have 
good control on the valves.

Once you have no more foaming in the jar and no more bubbles coming 
thru the oil, close the valve from the vacuum pump and turn the pump off.

Slowly open the valve on the manifold that does not have a vacuum 
hose on it. Then slowly open the valve to the jar. As the vacuum is 
released, it will suck any oil back into the cap if needed.

A bonus on the refer fittings is they have a tire type valve in them 
and when the hose is removed, it will close and trap the oil in the 
cap so you do not loose any oil plugging the hole.

If your cap is really air tight, you can even leave a small vacuum in 
the cap. Put a cap on the fitting as it has a rubber gasket in it and 
will be a back up seal as well as keeping dirt out of the fitting.

The jar is a common trap for vacuum applications, even vacuum casting 
for metal smithing uses this arrangement.

Frank

At 10:06 PM 9/13/2007 -0600, you wrote:

>---------- Forwarded message ----------
>Date: Thu, 13 Sep 2007 21:06:44 -0700
>From: huil888 <huil888@xxxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: vacuum and poly capacitor (fwd)
>
>Scott -
>
>I think the more conventional approach is to first fill the cap with oil,
>and then gradually apply vacuum. At the beginning of my Tesla coil
>experimentation I built three rolled capacitors in 6" PVC tubing with .060"
>polyethylene and super-thick aluminum foil, filled with Shell Diala-X HV
>insulating oil. I also used a "tee" fitting at the top of the cap, but had
>one leg of clear polyethylene tubing going straight up for about 20", then
>coming back down to the vacuum pump inlet. The other leg of the "tee" went
>to a small bleed valve. After filling the cap with oil, I connected up the
>vacuum pump & bleed valve. Fir degassing, first open the bleed valve and
>turn on the vacuum pump. Then, slowly close the bleed valve. At first, the
>air between the layers of the cap (and the air dissolved in the oil itself)
>will very vigorously boil and froth. The vertical leg of clear tubing allows
>you to control the bleed valve & the vacuum level to avoid having oil froth
>being sucked out of the cap and into the pump. The amount of boiling and
>frothing will gradually diminish, and eventually you will be able to close
>the bleed valve completely and apply full vacuum. The slightest defect in
>the gluing of your endcaps will result in a huge vacuum leak, even if it is
>small enough not to leak any oil.
>
>Regards,
>Scott Hanson
>
>
>----- Original Message -----
>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: <tesla@xxxxxxxxxx>
>Sent: Thursday, September 13, 2007 6:47 PM
>Subject: vacuum and poly capacitor (fwd)
>
>
> > Scott,
> >
> > Dave Baehr and I have both used vacuum to outgas a rolled cap.  I used a
> > vacuum pump and made sure that the enclosure was very air tight.  I used a
> > 6" PVC pipe with cap and then filled the bottom with epoxy up and over the
> > bottom of the pipe.  I used a T fitting and a threaded hole in the top of
> > the cap.  On one leg of the T the vacuum pump pumped and the other end I
> > clamped off the tube into the oil.  I then pulled a vacuum and once that
> > was done opened the oil line.  Make sure you close off the vacuum pump to
> > avoid putting oil into it.
> >
> > Chip
> >
> > ---------- Forwarded message ----------
> > Date: Thu, 13 Sep 2007 20:52:48 -0400
> > From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Subject: vacuum and poly capacitor
> >
> >
> > Hey guys,
> >     Would it be worth my time to build a poly-plate cap, out of PE
> > plastic and aluminum foil, and suck the air out of it with a vacuum pump,
> > before backfilling with oil (I know this is the era of the MMC, and I
> > actually don't even need a capacitor right now, but I have hundreds of
> > feet of 6 mil PE greenhouse plastic, which should make a decent cap if I
> > use about 10 layers).  My question is, If I use my air-conditioning
> > compressor (which I have used successfully for plasma globe work), what
> > kind of enclosure for the cap do I have to build, air tight, or just oil
> > tight, also when and how do I apply the vacuum.  Or, since I have so much
> > plastic, should I just not worry about the vacuum.  Like I said, I am
> > mostly toying with the idea, I am not in any immediate need of a cap right
> > now.  Thanks. Scott Bogard.
> >
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> >