DIY Vacuum Kiln . . . HELP!

[MemphisLogger]

Alright Den,

Here's yer chance to show off yer know how!

I was just offered a propane tank, roughly 10' long and 3' in diameter. It appears to be sound.

Before I manhandle this thing back to the shop, will it work as a vacuum kiln chamber?

If so, what do I need to make it into one?

Will the heat coils out of a large 220v ceramics kiln work for the heat (I have one that I'm not using)?

How big would my pump need to be to evacuate this tank?

I assume that I'll have to cut the end off the tank and turn it into a door for construction access and later for loading. Would added flange, rubber seals and adjustable hood hold-downs work for this?

Many more questions to come should this tank turn out to be practical.

[WH_Conley]

Don't know nothin about vac kilns, just be careful puttin the torch to that thing.

[MemphisLogger]

Thanks WH!

i hadn't even considered that yet  :-[  ;D

[Den Socling]

Yes, the tank will work. Yes, you should have professionals cut one end and weld on flanges for a door seal.

I would use Sergey's design. Circulate hot water (maybe from a little outdoor furnace) through piping that runs back and forth in the bottom half of the chamber. Put a trough top center and circulate 'cool' water through some finpipe. Stack and sticker your wood with a gap in the center. I can calculate a vac pump to give you various drying rates but, in the end, you can vary the heat to match whatever vac pump you have.

[MemphisLogger]

Yea!!!! Yippieyitiyay!!!!  

The fellas with the shop nextdoor to me do custom concrete castings and as part of their process have become master fabricators building the teel self releasing molds for complicated junction boxes, etc.

They're extremely nice having already offered to mix and pump all the concrete I want at cost. I'm sure they'll be more than glad to help with all the cutting and welding necessary--especially since they've been wanting me to rebuild their barn doors  ;)

What is the best way to attach the door?

Where can I find Sergey's design?

How does the water condensed by the cool water running through the finpipe exit the chamber under pressure?

Would the temperatures reached by an on demand water heater be high enough for the heating? Where I want to set it up would be convenient to wire (3 phase even) but complicated to plumb for gas or water.  :-/

If I used water for heat, I'd probably run the drainlines from my sump pumps to a passive heater/storage tank. If the controller thought the water needed to be higher, I could have an on demand heater in line and waired to the controller(?)  :P

Last question (not), can a cast iron aircompressor be turned into a vacuum pump?      

[MemphisLogger]

Hey Den, don't spend too much time responding to all the questions in my last post.  

I just found the "Vacuum Kiln" thread on all this and I'm studyin'  :P

I'm sure I'll come up with a slew of more challenging questions later  ;)

[Ga_Boy]

Hey Urban,

If you don't mind can you keep us upto date on your cost to put this beast intooperation.

After I get my convential kilns up, my next project will be a vac system.



Mark

[MemphisLogger]

Will do GA_Boy!

I'm goin' about this opposite of you. I hope to get the vac up so I can sell a few KD crotch slabs to pay for a Nyle  :D

Den,

I want you to know that your assistance will not be totally unpaid--I'll likely want a small controller from you!

[serg]

Hello, friends! I have transferred(translated) in meters. Diameter of 2.9 meters, length of 9 meters? ???? I want to lead(carry out) calculations. What thickness of a wall metal? ????
I think aircompressor the vacuum furnace poorly.
All my design on a site www.vacuums.ru  ;) Sergey

[MemphisLogger]

Sergey,

Have not me time do conversions now myself   ;);D :D

But I will double check yours as I give you more exact dimensions myself. The dimensions I posted to begin with are a guess from having seen the tank once and if it's like my initial judgement of logs, it'll actually be much bigger.  ;)

I would appreciate all the help you can lend  

I hear you on the compressor/vacuum question and I am looking into getting a good pump that I could use for laminations too.

How hot does the water in the heating coils need to be? How cold does the water in the condenser need to be?

Are you using stickers to separate the lumber in the chamber? If so, how thick?

I see on your website that your heating coils loop back and forth up the sides of the chamber. Can I use sweated copper for these or will that be a problem in the vacuum?

More questions and specs on the propane tank when I come up with them,

Scott    

[serg]

Scott, hello! You very well understand and correctly ask. I, on a forum can speak, write much. I shall tell the truth. The translator will tell all on the contrary :D ;DTherefore I do not want that you have gone in the bad way. >:( Sergey.

[MemphisLogger]

Ya best watch out Sergey, I'm fixin to get southun on y'all.  ;)

How does the translator do on that?  ??? ;D

[Den Socling]

GA-Boy,

If you get a vac kiln, a Nyle would bore you to death.

Urbanlogger,

A vacuum cylinder is normally around 5/16" thick. Pressure vessels are thicker.

The compressor won't work. Water won't compress. get a liquid ring pump that can swallow some water.

The heating water needs to be regulated between 95'F and 140'F. The cooling water should be under 75'F.

Use 'regular' stickers and spacing.

Sweated copper for the heating coils will be fine.

Den

[serg]

Hello! I completely also in part agree with Den. soon vacuum drying chamber should be in America. We shall meet. Sergey.

[MemphisLogger]

Thanks Den!

That's good news on the water temps--I was hoping that I could go with a passive tank and on-demand heater for the hot and a closed loop for the "cold". It sounds like I could at the temps you spec.

Sergey,

How  soon will you be in America? If I build this thing using your ideas and share my results with other DIYs, will I be steeping on your toes?

I look forward to having you come through Memphis and see my little operation. Maybe I could take you to see a couple of the biggest conventional kilns in the country that are just down the street from me.

Be good!

[Ga_Boy]

Den,

I believe you about the Nyle.  Just kidding Don.  ;)

As in my e-mail last night, I need to decide between two 1500 bf convential units or a vacuum unit.  Decissions, decissions, decissions......

I look forward to seeing you and Garrtett in a week or so.




Mark

[serg]

I  & partner, we have a lot of work Europe. One Germany, an exhibition Hannover. Two, delivery of the vacuum drying chamber to America. I shall inform in addition time. Sergey.

[old3dogg]

I sure am going to miss all of this vac kiln stuff but hey!
If you need someone to treat all of that process water that you are going to need send me an email. ;)

[MemphisLogger]

Whaddya mean treat? Couldn't you just evaporate it outside?

[old3dogg]

Unless you have an endless supply of clean,cold water for your vac pumps and condensors you are going to have to recycle your process water.Either with a chiller or cooling tower.This water will become bio fouled in no time.All of the slime that builds up in the cold loop will clog and rot your system.
I got out of drying[with vac kilns] and into water treatment.So now I can help with your process water treatment.

[Ga_Boy]

last night I found several Liquid Oxygen (LOX) tanks for sale as military surlpus.

The specs are 20' L X 8' X 9', pressure rating is 75 PSI
Temp ranges rating between Dang cold; minus a coupla hundered degrees F to plus a few hundred degrees F.  Material of construction is unknown at this time.

Would a tank like this work for a chamber assuming one of the ends could be modified with a door that seals?




Mark

[GaS]

I am wondering what happens to the strength of a cylinder when you cut the dome on the end off.  Does that open 'ring' then need reinforced or braced against the door to return some of the support that it had at time of manufacture?

A oxygen tank rated at 75PSI can withstand forces of 10,000 (75x144) pounds per square foot pushing out.  Pulling a vacuum on the chamber only exerts about 1700 (12x144) pushing in (not a hard vacuum, a 'serge' reduced pressure vacuum).  I can't imagine most tanks having any problem, unless it was some exotic design which was very specific to the forces involved.

[old3dogg]

All 8 of BWP's vac kilns are round.They have a steel ring welded around the outside of the chamber every few feet for suport.On 4 of these kilns both the front and back open.In the 10 years that I ran those kilns I have never had one collaspe.
I was pulling an average of 60 torr but on cold days or on near dry loads I could get down into the 40's.I would be afraid of anything below 35 torr on any chamber.
If you can get a chamber good enough to hold 60 to 70 torr you can vac dry.

[GaS]

Dennis mentioned that you can purchase flanges in a tremendous range of sizes...even to fit around a large pressure tank, if it is cut correctly.
The flange would brace the cut, open end and provide a way to clamp the door onto the body...
None of this had even occured to me, I think I'll go :P

[sawwood]

Den what size tank would you need to dry about
500bf of lumber. I don't have room here at the
house for any thing bigger. I have considerd a
solar kiln but its slow and the vaccum will do 8/4
better. I may think about this soon.

Sawwood