Molten Salt Bath - Update

Laredo7mm

Laredo7mm

Joined
Jul 8, 2002
Messages
1,240
Hey all, just wanted to give an update on my molten salt bath project. I got a couple 3/8 inch wall 3.5 OD SS tubes made up. One for the salt and one for melting bronze to try to do some of that bronze cable damascus.

I got my controller the other day, and last night I built the burner and the furnace. The burner is a Ron Reil style venturi, and the furnace is just stacked IFB. A little sketch is below with some dimensions.

I still need to get the thermocouple, the solenoid, plumb it, and build the sheet metal enclosure, but I fired her up last night for a test run. I put 18 pounds of bronze in the tube and lit her up. It was pretty sweat!:D There was tons of swirl and a good even heat. Just one hot spot where the burner enters the chamber. It sounded cool and the blue flame was shooting out the vent about 12 inches.

Anyway, I got that 18 pounds of bronze to go from 60 deg to full liquidus in 35 to 40 minutes. Man you gotta love it! Let me know if you all have any questions. The green is the tube, the purple is the firing chamber, and the yellow is the vent and burner inlet.

saltbath.jpg
 
hey, it melts salt too!:D Now I just need a solenoid valve. Anybody got any recommendations?

I did a quick test piece on 1095 tonight with a 50/50 mix of NaCl and CaCl2. Came out to 62 HRC after quench and absolutely no scale! I dont know what temp the bath was at but the steel came upto red in less than 30 seconds.

Thanks for all your guys help.
 
SKaer
If you check out Ron Reils page he gives info on a Stainless steel flare you can buy from this guy.
Larry Zoeller
4312 Lahnna Dr.
Louisville, KY 40216
USA

(502) 361-0706

I think they cost about 8 bucks.I bought one a few years ago and it fits very snuggly and securely on 3/4 inch(inside diameter) black pipe. I am just now getting around to building my first forge and so I am going to use the diagram for the burner you posted.
Thanks
Luke
 
excellent, thanks!

what kind of pressure guage/regulator do i need? ive got one from an Oxy/Acetl torch, will that do ok?

I'm very excited about this molten salt bath idea :)

So, your firing chamber is only 5 1/2'' in diameter?

does your forge have a top to it? (with a hole for the stainless salt tube?)
 
Yes, it has a hole in the top for the tube to go thru.

The flare on the burner is optional in my book. It is there to slow down the flow. It basically retains the flame front in/near the flare. What the flare does, is makes the flame stable when it is outside of the forge/furnace plus allowys you to use the burn at very low pressures, when your forge/furnace is cold.

I dont use the flares anymore. Once the interior of your forge/furnace gets hot, the flame is very stable. Before it is heated up the flame kinda dances around the end of the burner and is not really "adhered" to it.

Works for me, and I dont have to buy/make/replace flares. The one I have used ended up burning off anyway.

I bought a high pressure regulator from Menards. I think it was $18. It has a little port on the side that you can drill out and add a pressure gauge to it if you want. I did not add the pressure gauge to the salt bath reg., but my forge does have one.

Yup, chamber is 5.5 inches, which leaves 1 inch all the way around the cylinder.

My burner is a little different than the one you posted. I saw the modification somewhere, but cant remember where. But instead of having two little U clamps holding the small tube to the bell, I drilled thru the lip of the bell to allow the gas supply tube to pass thru the bell. Then I just drilled and tapped small holes for set screws to hold the tube in alignment above each of the thru holes.

Makes it easier to adjust/align the gas stream down the center of the tube.
 
Hey, sounds good buddy.

I bought my solenoids off of ebay...brand new Daytons. I THOUGHT I was bidding on 1, but when the box came there were 2! Pretty good for about $25 with shipping. They are $75 each new.

I made sure to get 1/8" orifice, normally closed, 120 volt. It has 1/4 NPT inlet/outlet.

Just make sure it will work with the controller you have :)

So what kind of ss are the tubes you got? Sounds like a heck of a deal.


Nick
 
I got the tubes from the scrap yard. And had the plate tig'd on here at work. They were about $25 a piece for the materials, and the welding was free.

Unfortunately, I dont know what alloy they are. Probably 304, but maybe 316. I am going to keep a close eye out for pitting of the steel from the molten salt. If she starts to corrode quick, then I think it would be 304.

I got my solenoid last night at a Industrial surplus place. ASCO Redhat, 1/4 npt, 120v, normally closed, 1/8 inch oriface. New old stock for $20.

Hooked up real quick last night and it worked just fine!

Do you all run a low pressure line also, or just the high pressure line to the burner. I have seen diagrams where there was a constant low pressure feed to the burner and when it dropped below temp, the high pres. would kick on.
 
I just run a main line to the burner. In some of my old books from school they list the ignition point of propane at about 900 degrees. Since I run my salt at least 1350, it re-ignites no problem.

My low temp salt is just in a small "pan" that I welded up and sits on top of a stove burner with a Brownell's heat-treating thermometer.

Sounds like you're well on your way!
Nick
 
Ring a ding ding! Got her plumbed and workin' I can only hold about +/- 5 deg F. The temp really jumps around some times, but I think that is because I am using an exposed thermocouple. But hey I ain't gunna complain about 5 deg. Oh, and no low pressure line was used.

I did a few more test pieces and got the C1095 to test out at 66 HRC. That is in a water quench, with a temp af about 50 deg F. Yeah, I know, but I am just playing and having some fun.

One thing I know for sure, don't use IFB. The stuff is cracking and falling apart due to the extreme heat ups and thin sections from cutting the radius in the bricks. Well, live and learn, not a big deal, gives me a good excuse to go to the scrap yard and pick up some large diameter pipe and line that baby with ceramic insulating fiber.

Man I love this hobby! :D I think I like building/buying the equipment better than making knives. Imagine that.:confused: Freakin' egghead engineers anyways...lol

Anyway, Nick....Have you decided if you are going to the Blade Show? I have my Hotel and Car reservations in, but I am waiting to see if I can get some free airline tickets from frequent flier miles. If I can, I am there.

Looks to be like a good time, plus I need to see some of the work you talented people do first hand.

Again, thanks for all your help.
 
hmmm, the IFB isnt holding up?

I had planned on building mine based somewhat off of ron reil's freon tank forge, only stood on end. I was going to cast in refractory cement mixed with vermiculite, then coat it. (you dont want just cement because it has too much thermal mass i believe and makes temp changes too hard)

i was trying to stay away from kaowool for health reasons. maybe my way will work, maybe not eh?

dont suppose you could elaborate on the plumbing of your system could you? maybe a picture of how things are connected inline would help me picture it all.

this is incredibly interesting.

just wondering, but how do you test for hardness?
 
The cast refractory should hold up good, just might take longer for the initial heat up. Should work better than the IFB.

My system is plumbed very simply; The pressure regulator out of the LP tank, into 1/4 black pipe, into the solenoid valve, into 1/4 black pipe, into 1/4 coupler, into the hose to the burner. All that is in one straight line.

Like Nick said, once you got the furnace upto temp, the burner will relight itself. I think you were planning just to "wing it" for a while before buying a solenoid and stuff. You should be able to get good results by just adjusting the amount of gas flow to the burner and testing for non-mag.

I have a little hand held hardness tester made by AMES. Suposed to accurate to +/- 1 HRC. They retail for about $1300, but you can pick them up used on eBay for around $200 - $300. I got mine for $0, from work. It was on the "to get rid off" list. Thankfully I got it before it went into the dumpster. Saved my Burr King from the same fate.:D
 
Hi All,

In case anyone is interested, I'm going to be offering kaowool, satanite, and ITC-100 for sale in small quantities for building forges and such. I'll put together a small web page with some information, prices and payment information over the weekend and make a post both to Bladeforums and CKD by Monday. I'll also have some with me at Batson's Symposium if you'll be there and want to save on shipping costs. Have a great weekend! :)

-Darren
 
I am using an exposed thermocouple

where do you have your thermocouple? is it "dunked" into the top of the salt bath, does it come from the bottom? (ie tapped hole in the bottom of the tube?)

how bad is your hot spot from the burner? any idea how much the temp is higher there?

thanks
 
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