Home made vac kiln

Tom L · July 24, 2013, 07:31:17 AM

it may have been hot out when you tightened it and cool when you tried to get it open.
seal seems to working better than expected

scsmith42 · July 24, 2013, 04:13:55 PM

Try heating the tank up. That will cause the air to expand to reduce the pressure on the door. Alternatively drill a hole or open up any existing bung holes to relieve pressure.

John.Howard · July 25, 2013, 08:12:49 AM

I think temperature may have affected it, but as we slightly damaged the gasket getting it open, I don't want to risk closing it again without a backup plan! I think we will probably weld a few 'tags' onto the flange. On one side we will drill a hole and weld a nut so that we can wind in a bolt which will push the other 'tag' and force it open. With 16 bolts to do the door up, adding more seems a bit of a pain! But I think that's just the way it has to be.

We haven't yet totally sealed the tank. It still had open holes when it was stuck. So far we have a floor drain with the vac pump connected, cooling water in, cooling water out and a pressure transmitter. We have yet to install heating water, feed and return. We were very lucky that the tank already had exactly the right amount of holes (unless there's something Den's not telling me?!). We had to adapt and make up a few fittings, but that side of things has gone quite well.

GeneWengert-WoodDoc · July 27, 2013, 11:21:01 AM

Try "butt butter" as known in the bicycling world, or Vaseline by others, at the gasket and other contact areas. We used that in the VK1000 vac kiln we had and it seemed to work well.

submarinesailor · July 27, 2013, 12:05:28 PM

We used something like this on missile tube door gaskets on the boats: http://www.amazon.com/Silicone-Grease-For-Waterproof-Gaskets/dp/B002RMFTLE. Also, have you concidered drilling and tapping the door flange just outside the gasket and using a bolt to force it off the seat?

Al - do you remember what the A ganger's used on the water tight doors between compartments?

Bruce

John.Howard · July 28, 2013, 11:57:13 AM

Thanks Gene. I had thought of using Vaseline but as I considered the problem to be suction I didn't think it would help. I see now it would create a good seal that would be easily broken. I didn't know cyclists went round rubbing it on their butts.

Bruce, you did a much better job of describing what I was trying to in my last post. Same idea, but as the gasket is almost the full width of the flange (4") and so as to avoid putting more holes in it, we were going to weld on 'tags' with a nut and bolt to force it apart.

mesquite buckeye · July 28, 2013, 12:03:49 PM

Once the unit is sealed, you can pressurize it to push open the door. Better have a gauge so you don't overdo it and blow the whole thing up..... ;D

John.Howard · July 28, 2013, 12:15:42 PM

We considered connecting a compressor, but it's a 1,300 gal tank so it would take a while!

mesquite buckeye · July 28, 2013, 06:57:02 PM

If you equalize the vacuum first, it wouldn't be quite so bad. You probably don't need more than 5psi to pop the end off. That's a lot of force over however big the end is, maybe 800 to 1000 sq inches. Maybe you would only need a couple if it isn't super stuck. ;D

submarinesailor · July 28, 2013, 07:01:37 PM

Quote from: John.Howard on July 28, 2013, 12:15:42 PM
We considered connecting a compressor, but it's a 1,300 gal tank so it would take a while!

Not really. If you put 1 psi in a tank, with a 2' door, that about 452.4 pounds of force on the door. 1 psi times the area of the door: 2' circular door=3.14159 SF x144"=452.4 sq in x 1psi=452.4 pounds of force. That's why submarines have safety latches on the water tight doors so that people don't get blown thru them or someone on the other side doesn't eat the door when it is opened while there is a DP across them. Lots of force involved. :

:

If you are thinkiing about using pressure to open it, I recommend you put some type of safety latch on it.

Bruce

PS - I hope I got all the numbers right................ :

:

Buck eye was 4 minutes faster then I was.

John.Howard · July 28, 2013, 07:33:53 PM

I've no idea how much force was needed to open it when it was stuck, but it seemed a lot. The tank weighs over a ton and when we were jerking at the door with the fork lift it was just pulling it along! The door is over 4' diameter. I'm hoping Vaseline will do the trick but I'm going to have a few bolts in to push it apart if needed. If it's still causing problems I will consider pressurising the tank but I'd rather something a bit more controlled than popping it open (like winding in a bolt!). We're not planning on doing it up for a couple of weeks. Our attention's on the heating system at the moment...

scsmith42 · July 28, 2013, 11:00:50 PM

Spray silicone may be a better option than vaseline. We use it in cold climates on door gaskets that stick, and it does not leave a greasy surface.

Den Socling · August 06, 2013, 02:31:37 PM

These guys are beginning to scare me. :D My son says all of my design work is going to end up in China and these guys are going to be rich!

If you have never seen a heating plate from one of my kilns, here are some on a load going into a chamber.

That's not a very good picture. For some reason, even though we have built thousands of plates, I couldn't find a good picture.

scsmith42 · August 06, 2013, 03:57:44 PM

Den, what goes through the heating plate - air, liquid, or something else?

Den Socling · August 06, 2013, 04:25:30 PM

Water that starts out at 100'F and ramps up to about 140'F.

John.Howard · August 06, 2013, 08:07:31 PM

We are hoping to be rich but through hard work, not selling out to China! So far this kiln has made me very poor. Is your load press, on top of the plates in the picture, inflated with compressed air? Here are some great pictures of your plates Den:

http://vacuumkilns.com/index.php/pcs-vacdry-kilns/25-material-handling

Thanks for your encouragement. Don't worry about your designs; we figure more vac kilns in the UK would mean more competition for us! And the Chinese seem to be into the high frequency vacuum kilns. ;)

Den Socling · August 07, 2013, 01:10:19 PM

Yes, John, that's a load press. Believe it or not, you don't need to inflate them. They always have a couple pounds of pressure in them. They are flat because of atmospheric pressure. When you reduce the atmospheric pressure, they expand and press between the ceiling and the kiln charge.

james04 · August 20, 2013, 01:46:55 PM

Den,

How much does a unit like the Vac Dry 1.25 cost? The unit with all the other needed components. I don't think I would ever be able to afford it. I am just curious.

Regards,
James

Den Socling · August 20, 2013, 04:42:28 PM

The cost is a ridiculous $100K. For $122,000, you can have one twice the size. As I'm always telling people, cutting capacity in half does not cut the cost in half. Take the welding of the heating plates, for example. The cost goes into the welding of the two ends. It cost the same for a 13 foot plate as it does for a 26 foot plate. And a VK1.25M uses the same control system as a 10,000 bf kiln. And stainless steel chambers with a huge amount of welding are expensive. I've always wanted to design a low cost kiln but it doesn't seem possible.

james04 · August 21, 2013, 10:14:36 AM

Wow. I thought it was going to be 1/3 of that. I am sure these systems are well worth the price of admission for those that can use them to there full potential.

" I've always wanted to design a low cost kiln but it doesn't seem possible."

I guess this is what I was hoping was possible.

I am very curious what the finished unit is going to cost these guys. I can see that they are quite capable fabricators and who knows what other hats are being worn during this build. I can tell it is taking a great amount of effort. Both in and out of the shop.

Regards,
James

mesquite buckeye · August 21, 2013, 09:21:52 PM

Maybe if you are a really good aluminum welder and can make the plates out of old beer cans. ;D

old3dogg · October 03, 2013, 04:44:32 PM

Hey Den.

Remember the time I vacuum packed a kiln charge of 3x3 RO in stainless steel?

Good times. ;D

mesquite buckeye · October 04, 2013, 11:33:26 AM

I hear they are making a low cost vacuum kiln out of adobes in Mexico, but after their submarine disaster, I don't know how well it will work. ;D

mesquite buckeye · October 04, 2013, 11:37:20 AM

Seriously, I wonder if you could build a vacuum kiln out of wood for strength with some sort of plasic overseal. Sort of barrel like. You would only need metal on the end cap. Hmmm

Is it possible to heat the wood with some sort of microwave energy instead of the plates?

Den Socling · October 04, 2013, 01:21:37 PM

Hi Mike,
I still tell the story of vacuum packed newels. I'll never forget that one. It's hard to believe that BWP is gone. All of the vac kilns were sold for scrap. :-\ I saw the list of equipment that was auctioned. It was everything. Right down to Mona's Crown Vic.

Buckeye,
All the wood would need to withstand is a ton per square foot. And radio frequency kilns were kind of like microwaves. I read at another forum about a guy who still runs RF/V kilns. They keep an electrical engineer on site.