Silicone heaters for your evaporating dish

[SkyHighLer]

I found the need to boil off multiple cans of butane quickly during my recent butane residue tests, here's how I do it. This is not what you should be doing unless you need to, and you're damn careful.

The silicone mat has it's energy sunk to the evaporating dish, otherwise it would immediately burn out at these power levels. The mat should be smaller than the bottom of the dish so full contact is ensured at all times. I don't power up the mat until I'm done extracting, as I don't want a large temperature shift breaking the dish, or have the dish get nudged off the mat, or have the dish break from dropping an extractor on it, etc., etc., etc.....

Notice the bottom surface of glass and ceramic cookware is uneven, three washcloths are used to insulate the mat from the surface under it, and to keep the pressure against the bottom of the dish even.

I have a mark on my dimmer that corresponds to ~200F without the dish on top, when doing a boil off I start at that mark and then take it up slowly up until I get a rapid boil and hold it there, dialing it down towards the end of the boil off. It goes quickly, I don't leave it unattended.

Not much in stock at Omega, it's order and wait as usual. http://www.omega.com/pptst/SRFR_SRFG.html

You don't need more than 5 watts per square inch, but I have a 10 watt per square inch because it happened to be in stock.

DIY dimmer,
https://www.icmag.com/ic/showpost.php?p=6063043&postcount=14

or a commonly available lamp dimmer,
http://www.amazon.com/Leviton-TBI03...81942416&sr=8-7&keywords=levitron+lamp+dimmer

Hit me up here or backchannel if you have any questions, if not implemented correctly this is extremely dangerous.

This will transfer much more energy than a griddle, which I absolutely don't endorse for a number of reasons... the mechanical thermostat being a possible source of ignition, poor contact with the bottom of the dish, etc...

 

[SkyHighLer]

Previously I was using a 1.25 watt per square inch oversized silicone heater, but the energy it could pump into the dish was limited by how hot I dared to get the areas of the mat that were exposed to free air. I used to run it with the exposed areas at ~160F, could have gone higher, but it would have only been a slight increase in boil off speed compared to a high energy density mat fully sunk to the dish and cranked up.

 

[SkyHighLer]

I found the wall dimmer combined with the small high wattage silicone heater won't operate in the lower voltage range needed to keep the temperature from rocketing up at the end of boil off, it just shuts off at a certain point when you dial it down.


I've wanted a variac since I was a kid, and seeing Gray Wolf's at the Skunk Pharm Research site rekindled my desire. They come in various amp/wattage ratings, and you should have one that's a third to fifty percent over rated due to turn on spikes with motors, etc. I scored a brand new whopper, a 20 amp, for about $110 at ebay. It's the exact same model shown in the video, so you'll know what to be looking for...
The little tweaks shown in the video aren't really necessary... it's indeed plug and play for lights, fans, heating elements, etc.

This video may be over your head, but it's a well presented overview,

http://youtu.be/D1jaTevZGWs?t=1s

If you at least skimmed through the video, you would have seen this is exactly what your mother told you NOT to use around exposed butane! The brushed contact area is exposed for cooling purposes, and should be considered a source of ignition. I have the safety issue covered down, please ensure you do the same.

It came today, double boxed, zero shipping damage. Sharp, like the guy in the video went on about, but also needing the same paint scraping to get the proper ground continuity. I could have just scraped under all three screw heads on the face plate, but instead worked on a third screw area that is hidden when assembled. Overvolts nicely, maxed out at 147 volts! The degree and span of control is awesome, I can adjust my silicone heaters by degrees down to ambient, and I had the computer box fan down to <60 rpm. The dial inaccuracy is understandable due to the basic design, but a more accurate voltmeter would have been appreciated.

Killer deal, I love it!

 

[Gray Wolf]

Hee, hee, hee............

 

[juggo]

Sweet!

peace,
juggo

 

[SkyHighLer]

Using a small silicone heater fully sunk to the bottom of my ceramic evaporating dish has worked out so well I ordered a silicone heater to fit the bottom of a three quart borosilicate* PYREX casserole dish. The pictures are of the Watlow 120 volt, 300 watt, 6" x 10" mat I have coming. It looks to have adhesive backing, so the mat will be securely attached and sunk to the dish, I'll just unplug it and move the dish/heater to the counter for the scape to parchment and then wipe it out with alcohol.

The VARIAC I just received combined with the new heater and a full size dish should be the way to go if precision and speed are important.


* Due to the heat differentials I can only recommend this with borosilicate PYREX. Mine is model number 233 N with Fireside tint.

"Fireside (1977)
This dark brown amber colour was the first decorative tint to appear in transparent Pyrex. Fireside remained as late as the mid 1990s, and the product line encompassed numerous shapes & sizes in baking pans (213, 222, 232, 233), pie plates (209, 229), custard cups (463, 465), casseroles (023/623, 024/624), and rimmed nesting bowls (322, 323, 325, 326)." http://corellecorner.com/clear-pyre...ansparent-fireside-cobalt-green-amethyst.html

"Older clear-glass Pyrex manufactured by Corning before 1998, Arc International's Pyrex products, and Pyrex laboratory glassware is made of borosilicate glass." http://en.wikipedia.org/wiki/Pyrex#Composition

Stuck the silicone heater to the borosilicate PYREX dish, added a plug, and I'm good to go. I'll post a picture of it rapidly boiling off butane during the initial test later today. The setup will be as shown with an extension cord between it and the VARIAC. This should be great for ethanol boil offs with a fan on it.

I was at the supermarket yesterday and examined a flint glass 'PYREX' casserole, and confirmed I've got a real boro piece.

 

[SkyHighLer]

I boiled off two cans of Neon 5X in the new setup and much to my surprise there wasn't a sea of bubbles, just a few streams here and there. I cranked the VARIAC higher and higher, but still no increase in the bubbling, and then the next thing I knew it was over, the liquid butane was no longer covering the mat area, and I dialed down from 75 volts to 15 volts, and in a few seconds more the dish was dry with a maximum dish temperature reached of 103F. Very fast, very smooth...

There was some condensation on the outside of the dish, zero inside, I didn't cover the dish during boil off. The picture taken near the end point shows the condensation build up.

I scraped and weighed the residue (Mystery Oil,) and the weight coincides with my previous findings for Neon 5X, ~0.004g per can.

 

[Cartel530]

I wannnnt! how much for the mat brotha?

 

[HG23]

Sky,

Do you use this type of setup with a vacuum chamber to fully purge extracts of butane or do you use a vac oven for that?

I'm curious if the cost savings of purging this way would make sense versus the ease of use of a vac oven.

 

[SkyHighLer]

I can't find an in stock supplier anywhere, here's a link to the ebay offering where I got the second to last one, I think Gray Wolf might have copped the last, the listing really is there, just scroll down,
http://www.ebay.com/itm/350889555440?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

That one is a 120 volt, 300 watt, 6" x 10" etched foil silicone heater with adhesive back.

Measure the bottom of your dish first, place the ruler across the bottom and notice the surface probably isn't even, you want a mat that will conform, leaving no gaps or exposed areas.

Here's what I will be doing, and suggest it to you...

Follow this link to a silicone heater manufacturer offering close to what you want, it's the wrong size and has no adhesive backing, but otherwise right on,

http://www.ebay.com/itm/Keenovo-Gui...610?pt=LH_DefaultDomain_0&hash=item4181665162

and contact the seller with a clear description of the custom heater you want. I suggest you link him to the ebay offering for the Watlow I have, and word the description exactly like I did above with the dimensions you want,

"120 volt, 300 watt, 6" x 10" etched foil silicone heater with adhesive back."

The wattage will change with the size, tell them you want about 5 watts per square inch.

I have a custom 12" round mat coming from them, they seem very eager to please, check out this post of the latest message I've received,

https://www.icmag.com/ic/showpost.php?p=6429609&postcount=16

Here's the link to the 20 amp VARIAC for $109 with free shipping,

http://www.ebay.com/itm/380909901186?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[SkyHighLer]

Sky,

Do you use this type of setup with a vacuum chamber to fully purge extracts of butane or do you use a vac oven for that?

I'm curious if the cost savings of purging this way would make sense versus the ease of use of a vac oven.

This is just for the initial boil off of solvents. I scrape to parchment, and vacuum purge in an aluminum stock pot heated with a 12" silicone heater and a DIY PID controller.

 

[SkyHighLer]

How to buy actual borosilicate PYREX dishes. They are still produced in the UK. The name of the company is Arc International. The product line is called Arcuisine. Amazon carries it,

http://www.amazon.com/gp/product/B00D91L1OQ/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

That's a three quart casserole dish, same exact size as my old piece pictured in the above posts. It came to $27 with shipping, about twice as much as you'd pay at the supermarket for the same size flint glass piece of shit, which imo no one should be using for much of anything... ;-)

I ordered the larger sized rectangular dish also, Amazon Prime covered the shipping.

I'm ordering a 6" x 10" silicone heater from China as I suggested above, and will also order one for the larger dish as soon as I can determine the size required.

 

[SkyHighLer]

They offered me a wire wound (instead of etched foil,) cool, after inspection maybe I'll be able to recommend these guys for wire wounds instead of Briskheat.

"eBay sent this message to XXXXXXX XXXXXXXX (XXXXXXXXXXX).
Your registered name is included to show this message originated from eBay. Learn more.
Seller has responded to your question about this item
Do not respond to the sender if this message requests that you complete the transaction outside of eBay. This type of offer is against eBay policy, may be fraudulent, and is not covered by buyer protection programs. Learn More

Dear XXXXXXXXXXX,

Hi John,

Thank you very much for your great recommendation. We appreciate it.

We'd be more than happy to work for you again with the new heater pad.
Here is the listing for you, the original price of the heater is US$40.50. We are gladly making 20% discount for you.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=271539717585

Before you place the order, I think I should let you know that:

1) The heater is not etched foil type, but wire wound type. Etched foil incurs a tooling fee and only recommended for volume source/manufacturing.They do not differ that much from each other as long as heating performance is concerned.
2) Free shipping via China Post air mail is included. A normal delivery period for it may be anywhere from 2 to 4 weeks to the US.

Please feel free to contact us if you have any questions.

And Happy Fourth of July!


Best Regards,

Johnny Tang

- keenovo
Click "respond" to reply through Messages, or go to your email to reply

Respond


From: XXXXXXXXXXX
To: keenovo
Subject: Other: XXXXXXXXXXX sent a message about Keenovo Guitar Cutaway Bending Silicone Heat Blanket 6"X12" 350W 120V #281343840610
Sent Date: Jul-03-14 08:57:37 PDT

Dear keenovo,

I'd like to order another heater.

120 volt, about 5 watts per square inch (300 watt?), 6" x 10" etched foil silicone heater with adhesive back.

Please send me a custom heater ebay link for it and I'll complete the transaction.

Thanks, John XXXXXXXX

Btw, I recommended you on the internet, post #10 here,
https://www.icmag.com/ic/showthread.php?t=286598"


And thank you for fireworks! )

 

[YouGrowBoy]

I have a mark on my dimmer that corresponds to ~200F without the dish on top, when doing a boil off I start at that mark and then take it up slowly up until I get a rapid boil and hold it there, dialing it down towards the end of the boil off. It goes quickly, I don't leave it unattended.

Lurking and reading! SkyHighLer, do you now not recommend your diy setup with the light dimmer and mat since buying the more professional setup?

 

[SkyHighLer]

Lurking and reading! SkyHighLer, do you now not recommend your diy setup with the light dimmer and mat since buying the more professional setup?

The VARIAC is so much better at low temperature control, I'll probably never use the lamp dimmer for that purpose again.

VARIACs should be considered a source of ignition, I keep mine elevated, at a distance, upwind.

 

[SkyHighLer]

Boro Pyrex dishes came, the larger turned out to be the same size as my old dish. Both have a two inch wide raised 'island' on the inside surface, about as thick as a razor blade with steep walls. What were they thinking?

The Keenovo heater looks as nice as the Watlow, I'm going to use it with the smaller dish. Here's my eBay custom order for reference, scroll down the page, all the info you need to make your own custom order with them is there,
http://www.ebay.com/itm/271539717585?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[neeee1]

I got my omega mat and went to ACE to purchase a 2 prong plug similar to this one http://bit.ly/1sVTOqA but I'm a little worried with how 'open' it is. Im wondering if there ever was a spark, wouldn't the spark, if large enough, come out from under the plug, possibly causing a fire if near butane? If I was to cover each prong with electrical tape where the screw and exposed wire meet, would that be sufficient to mute a spark and prevent an explosion?

As long as you do a neat job of attaching the wires there will be no sparks, but this is a vacuum chamber thread, here's a thread I started about heating evaporating dishes with silicone heaters.

https://www.icmag.com/ic/showthread.php?t=286598

If your going to use a silicone heater larger than your dish, it should be very low wattage, like 1.25 watts per square inch, and you're still going to need to adjust the output with a dimmer or a VARIAC. The VARIAC is smooth, I used mine today for a run, slick, but very dangerous if not used with proper isolation from any open butane.

Hey Sky, posting in this thread now.

I understand that the screwing is supposed to stop the likelihood of sparks but I want to be 100% it won't happen. Granted I will be using this under my vacuum chamber with terry towels so I don't expect a large presence of butane but in case I decide to experiment with the mat for the initial purge after blasting into Pyrex. I was thinking of putting a couple strips of electrical tape over the area where the prong and wire meet but don't know if this would have a negative effect. I'm just worried because there seems to quite a bit of space inside the plug with the omega cables being so thin.

 

[SkyHighLer]

Hey Sky, posting in this thread now.

I understand that the screwing is supposed to stop the likelihood of sparks but I want to be 100% it won't happen. Granted I will be using this under my vacuum chamber with terry towels so I don't expect a large presence of butane but in case I decide to experiment with the mat for the initial purge after blasting into Pyrex. I was thinking of putting a couple strips of electrical tape over the area where the prong and wire meet but don't know if this would have a negative effect. I'm just worried because there seems to quite a bit of space inside the plug with the omega cables being so thin.

The only way you could get a spark inside the plug is if:

1) One of the wires comes loose

2) A loose strand of wire crosses to the other prong

3) Some conductive foreign object gets inserted

Do a good job wiring the plug and you'll never have a problem with it.

The silicone heat mats have zero protection against burning up without proper control, please be careful.

 

[neeee1]

The only way you could get a spark inside the plug is if:

1) One of the wires comes loose

2) A loose strand of wire crosses to the other prong

3) Some conductive foreign object gets inserted

Do a good job wiring the plug and you'll never have a problem with it.

The silicone heat mats have zero protection against burning up without proper control, please be careful.

I picked up a dorkfood dsv to help maintain temp. I'm also thinking of making a pid controller like you've posted but that's down the line. I did plug in the mat by itself and my god it hit 375 in under 30 seconds. But with the dsv temps are staying in range but sometimes it over shoots it. Guess it'll take a bit more playing with.

 

[SkyHighLer]

I picked up a dorkfood dsv to help maintain temp. I'm also thinking of making a pid controller like you've posted but that's down the line. I did plug in the mat by itself and my god it hit 375 in under 30 seconds. But with the dsv temps are staying in range but sometimes it over shoots it. Guess it'll take a bit more playing with.

That's way too hot, how many watts per square inch silicone heater did you get? If your going to use an oversized mat with unsunk areas exposed to free air you need to stick with the lowest wattage mats, like the 1.25 watt per square inch Biskheats. There's a wattage density versus temperature chart here http://www.omega.com/toc_asp/frameset.html?book=Heaters&file=Intro_flexheaters