# Advise on heater for 30 liter vessel



## 72chevel (Apr 2, 2015)

I recently purchased a Prism Research vessel and am wondering what heater I should use to heat it? It has a 1 inch port coming out the bottom of it so I do not think a standard type heating mantle will work. Any suggestions?
http://www.prismresearchglass.com/product/30-liter-vessel-a-300mm-flange-315mm-o-d-x-670mm-tall


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## goldsilverpro (Apr 2, 2015)

Maybe an immersion heater plus a controller like they use in plating tanks. They make them out of most anything - quartz, titanium, SS, carbon steel, etc. 

Electrical heating tape?


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## Lou (Apr 3, 2015)

Let's see some photos.


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## 4metals (Apr 3, 2015)

Try a soft heating mantle, they come in all sizes and can accommodate a bottom drain. Since they heat the outside of the vessel there is no issue with solution compatibility. One thing to be aware of is the height the mantle goes up the wall of the flask. Order it so the solution level will not go below the heated portion of the flask. It is OK to have the solution above the mantle, as the warm solution rises and circulates but if the solution goes below the level of the mantle you risk overheating the glass at the heated/not heated interface, and that can cause breakage.


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## Lou (Apr 3, 2015)

On our 100 L QVF stuff that we use, we have these blankets that wrap around the cylinder form.

Heating mantles/jackets are NOT cheap. Period. 

Lou


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## 72chevel (Apr 3, 2015)

Thanks for the replies thought I found the perfect mantle with a hole in the bottom but then saw it was $1300!!!!
If I was using Sodium Thiosulfate could I rig up just a normal water heater element?


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## 4metals (Apr 3, 2015)

I have also had good luck using these heat blankets. 

http://www.briskheat.com/c-73-silicone-rubber-heaters.aspx

Brisk Heat people are very professional and their silicone heaters can work but will not get as hot as a heating mantle.


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## 72chevel (Apr 4, 2015)

Yea looks like around a $100 that sounds really good! I'll check them out! Thanks


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## Palladium (Apr 4, 2015)

With one of my silver builds i built a system for a fellow out of a stainless 30 gallon drum mounted on a drum swivel for dumping. On the bottom of the drum i had a plate welded and tapped for a hole in which i used a stainless water heater element to heat the solution and a water heater thermostat to regulate the temperature. It was nothing more than a nitric water heater! Redneck, cheap, and worked like a charm. First element burnt out after 14 months. It took $25 and 5 minutes to change it out.


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## 72chevel (Apr 4, 2015)

that last longer than I thought it would! Thanks for the insight!


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## tunnel_run (Sep 25, 2018)

Though silicone rubber heaters are bendy the ones I see are flat. Manufacturers appear to cut them into most any custom shape but not a bowl. A long rectangle can wrap around a cylinder with good contact but it poses a challenge for round vessels and heating the bottom of curved bottom cylinders. I like the idea of less expensive alternatives to mantle heaters and I am pondering DIY methods that could get more vessel coverage. Perhaps even a unique design that could be taken to a custom flexible heater manufacturer. I decided to mock one up using a small flask as the basis for a proof of concept. I’m using a 250ml flask so we’re obviously working on a much smaller scale. A 30L vessel has a lot more to heat! I’m also contending with what is likely to be much tighter curves. I'm content with a small temperature rise at this point just to explore shape and form.

Here is what I’ve tried so far. I started this exploration by cutting and peeling an orange to come up with a flat-ish shape that, on a larger scale, could be cut out of a larger piece of silicone rubber.




Then I coated the flask with rubber, let it dry, cut it like I cut the orange peel and then pealed it away from the glass so I could take a look at it. It doesn’t lay totally flat but good enough for this little experiment. So far so good. I reapplied it to the flask and it just sort of sticks there by itself.




I measured and guestimated what length of resistance wire I could easily fit into my experiment. Using this calculation for resistance…

Resistivity * Wire Length/Area at Cross Section of the Wire = Resistance

I explored heating element wire types and gauges and finally settled on 26 gauge stainless steel. In my research I found that there are different types of stainless steel alloys used in heating element wire and the resistivity falls somewhere within a range depending upon the wire you buy. I don’t know what the resistivity of my specific wire is so I’m using the middle of that range.

24 Gauge Stainless: 0.00000074 * (2032mm/0.205mm) * 1000 = 7.335 ohms
26 Gauge Stainless: 0.00000074 * (2032mm/0.129mm) * 1000 = 11.656 ohms (I chose this one)
28 Gauge Stainless: 0.00000074 * (2032mm/0.081mm) * 1000 = 18.564 ohms

I then ran the wire through a device usually used to roll up paint or toothpaste tubes to get all of the material out. It created a nice series of bends making it easier to pack in more wire and cover more surface area.




The math says I’ll have 11.7 ohms. I checked the resistance and it’s pretty close to my calculation. I bent the wire to roughly achieve the shape I wanted.




I then started pressing parts of it into the silicone rubber while further dabbing fresh rubber until it thickens a bit and starts to hold the wire in place by itself. I then dipped the whole thing a few times to add an outer layer with some amount of thickness. The rubber is electrically insulating but thermally conductive. I then re-cut the slits and peeled the heater off of the flask. Not so flat in this version.




I’m limited by the temperature handling of the rubber which is very low but it was enough to see it in action. I’ve since ordered some high temperature silicone rubber mats that I intend to cut into essentially the same shape but with more longitudinal cuts. I’ll also try to pack in more resistance wire and beef up the watt density. Then vulcanize it, wrap some insulation around it so I’m not putting so much energy into heating the air and finally see if I can boil some water with it.

I'm wondering if there are common vessel sizes to consider. I appreciate suggestions.


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## FrugalRefiner (Sep 25, 2018)

tunnel_run, that's an interesting idea. I edited your post to remove the link because we only allow commercial links in the Refiners, Buyers, Assayers, etc. section of the forum.

Dave


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## cuchugold (Sep 26, 2018)

A direct flame works quite well in a metal pot covered with fiberglass and resin.


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## tunnel_run (Dec 14, 2018)

I made a wire wound silicone heater with a higher watt density sandwiched within high temperature silicone rubber sheets and glue...


... cut, shaped and assembled the parts...


... and boiled some water.


It works! I'm speaking with a custom heater manufacturer about making a more polished and effective solution.


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## tunnel_run (Mar 5, 2019)

A tool to configure your own silicone rubber mantle heater.


You can dynamically create heater specifications on the fly.
https://farnam-custom.com/custom/silicone-rubber-heaters


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