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Author: Subject: Are there chinese hotplates & heating mantles as good as others but significantly cheaper?
fusso
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[*] posted on 22-5-2018 at 18:04
Are there chinese hotplates & heating mantles as good as others but significantly cheaper?


Chinese glass labware can be as good as others but significantly cheaper, so what about hotplates & heating mantles? If they're significantly cheaper, should I trust them?

[Edited on 23/05/18 by fusso]




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[*] posted on 22-5-2018 at 18:14


You can get some really good Corning hotplate/stirs for between 130 and 200 dollars, especially used. I would either buy one of those or make a heating mantle from parts.



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JJay
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[*] posted on 22-5-2018 at 18:38


I use Glas-Col fabric heating mantles, which I regulate using simple electronics equipment that I wired together. They are pretty inexpensive on the secondary market, less expensive than the Asian heating mantles. I don't think the Glas-Col mantles are extremely durable, but I haven't had any problems with mine. The tricky part is finding one with a power cord.

[Edited on 23-5-2018 by JJay]




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coppercone
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shocked.gif posted on 22-5-2018 at 19:46


I don't know if you wanna go there.

Think about this, if you are doing something dangerous, you really don't want the regulation to fuck up do you?

I would recommend buying USA equipment and doing a internal inspection to verify its integrity, and replace things like worn wires, and keep it very clean (i.e. clean it after doing a reaction or having a spill, don't keep some messy ass crusty hot plate around because electronics don't like that shit at all). Polish it too if you can so its easier to clean up.

The chinese like to rate things about 2 or even 3 times more then they should be used for in moderately high reliability applications.


I can't speak for more simple things, like heating blankets... but things like Chinese Variacs, transformers, heater controller/PID, control boxes should be treated as suspicious. At least replace the fuses with ones you buy from a trusted supply chain (digikey.com, farnell, etc... don't buy safety components on eBay) And wire in a ground fault interrupt circuit in case a condenser blows up or some shit. And check your laboratory ground.

If you look at it from a 'my ass is on the line' kind of viewpoint, even American made is not that great due to bean counters.... if you work for a company unfortunately you can be considered 'good' if you say things like 'its safe enough'



For instance:

Chinese variac: rating : 20 amps or so, weight : 25lbs

American 1970's variac (sometimes regarded as a golden age of manufacturing certain goods): rating : 8 amps, weight :25lbs

Did silicone steel and copper conductivity increase by 200% while I was away?

Now, maybe you can run them somewhat hotter, because maybe enamel coatings on wire got better. But 300% ? :P:o

the last thing you want is a laboratory fire right?

case in point:
http://www.newark.com/superior-electric/3pn236b/variable-tra...

Rating : 10 amps, nice spec sheet, weight, 22lbs, 1600$ (like 100-400 on ebay)

https://www.circuitspecialists.com/variac-tdgc2-2.html
20 amps, 25lbs, 99$

lets divide the sale price by 4, because its industrial, and a bit niche nowadays since we don't use so much tube equipment and other things that require variacs as we did 30 years ago.

do you trust : 1/4 the price, half the weight, twice the rating? :P
(really 1/16th the price!, saying 1/8th is still being modest, 1/4th is generous).

I also want to say, given my knowledge of electrical code, that outlet looks to be a 15A outlet............

http://www.airforums.com/forums/attachment.php?attachmentid=...



[Edited on 23-5-2018 by coppercone]
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[*] posted on 22-5-2018 at 21:13


I use a triac dimmer instead of a variac... they are much cheaper and lighter. My PID controller and relay are Chinese, but they are decent industrial-quality components, and they weren't cheap, although they were much cheaper than they would have been if I had bought them in an American electronics store. The controller functions well and accurately as long as it doesn't have to react to conditions like a flask suddenly boiling dry or the power getting immediately increased from 25% to 100% when only 10 C away from the target temperature. The PID controller has some sort of serial interface, but I haven't bothered with it. If I wanted to get really fancy, I'd figure out a way to automate the triac, but so far I have only needed a temperature controlled heating mantle for one experiment.

If you're afraid of playing with the wall current, the heating mantles made in India with built-in controllers might not be such a bad deal. Glas-Col does make temperature controllers, and I'm sure they are reasonably good quality, but they are rather expensive.




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[*] posted on 22-5-2018 at 22:50


It may work well but your chance of getting counterfit chips from the shenzen market increases drastically, as does things like proper assembly procedure not being followed (i.e. esd precautions leading to some kind of failure)

chinese inverters for instance are a complete joke.

also high power triacs may be significant noise generators so poorly shielded things may not interact well with them

[Edited on 23-5-2018 by coppercone]
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[*] posted on 22-5-2018 at 23:10


Quote: Originally posted by coppercone  

case in point:
http://www.newark.com/superior-electric/3pn236b/variable-tra...

Rating : 10 amps, nice spec sheet, weight, 22lbs, 1600$ (like 100-400 on ebay)

https://www.circuitspecialists.com/variac-tdgc2-2.html
20 amps, 25lbs, 99$

lets divide the sale price by 4, because its industrial, and a bit niche nowadays since we don't use so much tube equipment and other things that require variacs as we did 30 years ago.

do you trust : 1/4 the price, half the weight, twice the rating? :P
(really 1/16th the price!, saying 1/8th is still being modest, 1/4th is generous).

I also want to say, given my knowledge of electrical code, that outlet looks to be a 15A outlet............

http://www.airforums.com/forums/attachment.php?attachmentid=...

[Edited on 23-5-2018 by coppercone]


Your comparing a current ratings of a 240V 50Hz, system with a 110V 60 Hz system.

You have to compare VA ratings for a fair comparison, and be careful as to how the ratings are defined,

For example the 20A variac is rated thus:
Rated up to 20 Amps or 2kVA Peak (16A Continuous)

The maximum current is frequently limited by the brushes in addition to the VA rating.

Edit:removed reference to 2kHz


[Edited on 23-5-2018 by wg48]
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fusso
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[*] posted on 23-5-2018 at 15:09


I cant understand what most of you are talking about???



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[*] posted on 23-5-2018 at 16:40


My observation is that members who have Corning hotplates are very pleased with them.

I used the cheapest (1500W) generic hotplate for a couple of years,
then I replaced the on/off internal temperature controller with a cheap Chinese triac controller (description=4000W) which, due to continuously variable constant power worked very well for distillations.
Eventually I killed it by overheating during a sulphuric acid concentration at >300oC.
So I bought a used generic dual hotplate (1500W + 500W) that is still in use,
for heating beakers and an oil bath.

My favourite heater is my diy 500ml heating mantle, <£10 for the mantle and triac controller,
add a suitable container and some insulation and you're done.
Except - my diy magnetic stirring is not yet working as I want it to.

Overall:
IF you are comfortable working with mains electricity then together with one of the cheap Chinese triac controllers,
either a DIY mantle
or
a cheap hotplate (you can kill a dozen cheap ones for the cost of a used Corning hotplate)
is my recommendation.

P.S. Initially I did not appreciate the value of stirring - now I do :D

[Edited on 24-5-2018 by Sulaiman]




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[*] posted on 23-5-2018 at 17:01


a friend of mine in china owns a lab glassware factory. he is well connected with lab equipment in china. he asked me to send him an australian stir-hotplate. i think that probably sums it up fairly well.



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[*] posted on 23-5-2018 at 17:08


Coming soon ... a cheap Chinese version of an Australian hotplate-stirrer :P



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[*] posted on 23-5-2018 at 17:23


Quote: Originally posted by diddi  
a friend of mine in china owns a lab glassware factory. he is well connected with lab equipment in china. he asked me to send him an australian stir-hotplate. i think that probably sums it up fairly well.

Conspiracy theory: he probably wants to study its structure and electric circuits so he can replicate it and sell at a lower price :P

[Edited on 24/05/18 by fusso]




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[*] posted on 23-5-2018 at 17:28


Quote: Originally posted by Sulaiman  
Coming soon ... a cheap Chinese version of an Australian hotplate-stirrer :P


How exciting :)

The Corning stirplates are satisfactory for most purposes. They have a strong magnet and a reasonably high heat output, not to mention a chemically resistant top surface. They are not really designed for extremely precise temperature control, but it's usually unnecessary. I remember seeing a Chem Player video where a Corning stirplate was used to hold the contents of a flask within a narrow temperature range for hours.





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[*] posted on 23-5-2018 at 17:57


I have a cheap mag stirrer hotplate from china. its called 85-2
https://www.ebay.com.au/itm/AU-220V-85-2-Lab-Magnetic-Stirre...

it works as a starter unit ( but it only cost $70 aus) its slow to heat and its probably crap. but it seems ok as a starter for me. the temp regulation seems OK,

Just My humble option, but unfortunately as a newbie - i dont know yet, what I dont know.

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[*] posted on 23-5-2018 at 18:16


I also have an 85-2. I don't really recommend them, but I do use mine occasionally for heating mixtures slightly above room temperature or stirring reactions that don't require heating. I used to use my 85-2 at temperatures up to about 220 C with an oil bath heated by an immersion heater, but it is more convenient to use a higher-temperature stirplate.



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[*] posted on 24-5-2018 at 20:29


Quote: Originally posted by fusso  
Quote: Originally posted by diddi  
a friend of mine in china owns a lab glassware factory. he is well connected with lab equipment in china. he asked me to send him an australian stir-hotplate. i think that probably sums it up fairly well.

Conspiracy theory: he probably wants to study its structure and electric circuits so he can replicate it and sell at a lower price :P

[Edited on 24/05/18 by fusso]


We can hope.
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[*] posted on 25-5-2018 at 03:45


Send him a good quality unit! then we can get a half descent knock off!

Trick with allot of Chinese gear is divide the continuous rating by 3 to get the real one.
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[*] posted on 25-5-2018 at 13:45


I bought a couple of ancient, semi-functioning, American stir-plates, a few years back.

Cheap as dirt, on e-bay. It was almost embarrassing, price-wise.

No fancy bells and whistles, just high-quality component, low-tech construction.

After about an hour, by skillful use of a screw-driver and a scribe, both were humming along like new.

"Parts left out of the design, do not break!"

The more sophisticated the electronics, the greater the probability of failure... And, the greater the difficulty of repair.

I've purchased some great things from the Chinese, at great prices. Electronics however, are not on my list of acquisitions.



[Edited on 25-5-2018 by zed]

[Edited on 25-5-2018 by zed]
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[*] posted on 26-5-2018 at 14:28


So...... The Staco-type Variacs, that are so common(used), in the U.S.A., currently list for about 1,500 Dollars per unit....New?

I'm sold! Just bought one used, in very nice condition, off of e-bay, for 60 Bucks, including shipping!

Guys, you are golden! Thank you, for your continuing wisdom.
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[*] posted on 26-5-2018 at 14:58


there is maintenance you can do on them like polishing the slider, cleaning off dust, checking the wiring, etc.

I highly recommend building it into a (properly grounded) steel box with a current, volt meter and power meter (might be more useful for chemistry), fuses, outlet plug, ground fault interrupt if you does not have one already (I would put 2 outlets one with GFIC and one without)

Possibly a new extension cord

For electronics work you might want to buy like a sufficiently rated EMI-Mains filter and wire it in to the front.

Unless you got a finished one in a sheet metal enclosure they sell it in, then you just need to check it. I got my variacs cheap but they were without enclosures, just the magnetic element.

https://www.ebay.com/itm/100A-AC-LCD-Panel-Digital-Power-Wat...

shit like that kind of works, but I have one without a independent power supply, so it stops working when you get under like 30 volts. Best would probably be either an electronic one powered by separate power supply

I actually don't know if the analog power meters will actually have a multiplication circuit and measure voltage/current independently or if they will make an assumption.

I think they do:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l...

one of those should work even better since you only care about watts for things like heating mantles

most of them are for RF but here is one, but the current is too low
https://www.ebay.com/itm/Lab-Volt-Simpson-Single-Phase-750-W...

something like that but going to 1000 or 1500w is what would be best imo


here we go:
https://www.ebay.com/itm/TEST-EQUIPMENT-WATTMETER-SIMPSON-13...

not the best resolution but for 15$
should put current meter too though, so you know if fuses are gonna blow

[Edited on 26-5-2018 by coppercone]
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[*] posted on 26-5-2018 at 20:21


LOL to all the knock off conspirators, but it was for himself. i had a cheap one with digital display etc from china and it nearly burnt my place down. luckily i was using it outdoors when it literally melted itself into a fuming pile and i was close by to avoid a disaster



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[*] posted on 27-5-2018 at 06:41


a chinese variac? or the little panel meter? Those meters should be fused so it should not be too much of a fire hazard..

how come fuses did not work?

also a good mod would be to put a fusable thermal fuse on the transformer body to disconnect it if it gets more then like 150c

[Edited on 27-5-2018 by coppercone]

[Edited on 27-5-2018 by coppercone]
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[*] posted on 27-5-2018 at 14:10


i was concentrating some H2SO4. the whole plastic surround simply caved into a molten mass. i had it outdoors because i dont have a fume hood. i noticed the beaker was on a lean and went to investigate. no fuses blew tho.



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[*] posted on 27-5-2018 at 14:46


My Cheap Korean hotplate/stirrer has been through hell and back.

Still trucking almost 100% after 4+ years of daily abuse, including 2 cycles of grinding/repainting.

The 'off' position for the heating control gave up about 10 days ago.

Easy to fix (replace the pot) however i have other, more interesting plans for it.

Dear 'fusso', just use a cigarette lighter or candle or something until you decide on the most appropriate hotplate/stirrer to buy.

Reporting your Chemistry experiments would be far more interesting than a re-hash of many old threads.

I'd get all giddy if a noob even made copper sulphate crystals.

[Edited on 28-5-2018 by aga]




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[*] posted on 2-6-2018 at 03:05


Quote: Originally posted by aga  
Dear 'fusso', just use a cigarette lighter or candle or something until you decide on the most appropriate hotplate/stirrer to buy.

Reporting your Chemistry experiments would be far more interesting than a re-hash of many old threads.

I'd get all giddy if a noob even made copper sulphate crystals.[Edited on 28-5-2018 by aga]
I do have experiment plans and chemicals in my "base" in my home country but I'm currently in another country so I can only do experiments after going back home. I usually use a blowtorch to heat rxn mixtures but I need a hotplate for controllable temperature.

[Edited on 02/06/18 by fusso]




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