joeflsts
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Heating Mantle question
Is it possible to use a Glas-Col controller (variac) with an Electrothermal mantle? It would seem to me that as long as the wattage doesn't exceed
the controller specs this should work. Am I wrong?
Joe
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Sauron
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That ought to work as long as the connectivity permits.
I used to buy used mantles on eBay and LabX. (almost all Glas Col). Often they came with no power cords, and I had to kiss the ass of the Glas Col
agent to get these. Glas Col used a variety of 2-wire, 3-wire and grounded/ungrounded pigtail connectors, very frustrating.
Finally I sold off all my old mantles and presently have a 1 L Electrothermal bought new with built in controller; a 3 L Glas Col TM and a 5 L Glas
Col TM, and a pair of 72 L Glas Col TM as well as a dinkt little 250 ML TM. All of those (except the jumbo 72 L's) are run off of a PowerTrol. No more
variacs, no more Ace temp controllers.
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Magpie
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That seems right to me. I bought an old 360w variac type controller really cheap off ebay. I use it on my 2 Glas-Col mantles, both of which draw
less than 360w at line voltage (120v). I haven't had any problems.
I did notice that the controller, which I believe uses the principle of an autotransformer, will put out up to 140v. So be aware of that
possiblility.
[Edited on by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Ozone
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They are interchangable, just make sure your controller can deliver the wattage that your mantle (or set thereof, for that matter) requires. You can
easily determine this by measuring the resistance of your mantle(s) with a multimeter. Using your mains voltage and the resistance, calculate the
current (good old VIR eqn.). Then, use W=I2R to calculate the watts required.
edit: just to clarify, that's I *squared* R. Must...learn...BB...
This is really handy if you want to run more than one mantle with a single controller.
Cheers,
O3
[Edited on 14-4-2007 by Ozone]
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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joeflsts
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Thank you!
I suspected this was the case. I just didn't want to find out that I was wrong - punctuated with a cloud of smoke!
Joe
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Sauron
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Ought to be OK as these are just ac resistance devices and the controllers are PID mostly. No polarity issue.
My controller (Glas Col Powertrol) is NEMA in and out which I do not much like as it is a pretty sloppy electrical connection IMO.
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S.C. Wack
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Glas-Col makes variacs? Thought they were all solid state.
What gets me about Glas-Col is their use of male grounds on some mantles, and female on others. Can't imagine why unless it's an era thing. One
plug/cord is interchangable with Electrothermal, the other not.
I like and recommend the old Cole-Parmer solid-state control, now replaced in the catalog with a variac. Not any cheaper, of course.
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Sauron
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No, Glas Col does not make or sell variacs, but the use of a variac as a controller is still common.
In this country the Glas Col agents are nice people while the Cole Parmer agents, and sometimes Cole Parmer itself, sometimes have their heads up
their asses.
I agree with you completely about Glas Col's profusion of plug types. In addition to male vs female grounds (center posts) a lot of older Glas Col
mantles are ungrounded especially fabric types.
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Magpie
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I have two Glas Col mantles, old woven fiberglass type. The 100 mL is 80w and the 500 mL is 270w. Both have a small coil of wire on the bottom. I
was never sure what these coils were and have just ignored them. Ground wires?
The mantles have 2 prong male plugs. These plugs will only fit a special cord with the corresponding female end. Fortunately these cords came with
the mantles in my ebay purchase.
The single most important condition for a successful synthesis is good mixing - Nicodem
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S.C. Wack
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Those wires are for the internal type J thermocouple. The newest mantles that I've seen do not have them.
It is good that you have the old weave-covered wires and plug, because the plugs for the more recent mantles are too big. So if one has a collection
of Glas-Col mantles from different eras, they need 3 different plugs. I wonder if Electrothermal did the same thing.
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chemrox
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where do you get Glas col plugs? they never come up on ebay.. I've got two 1L aluminum cased mantles for cylindrical bottles and I've got some 1L
bottles with 24/40's. I got the mantles for these and they came sans cords. somebody should have been shot..
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bio2
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A so called "infinite switch" like the ones used on range
burner elements makes a good controller and works as
a percentage timer using an internal heated bimetal.
My stirrer/hotplate also uses one of these. They can
easily be scavenged from old oven/ranges or just
buy one at the appliance parts store.
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Sauron
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@chemrox, talk to your Glas Col agent and tell them you need the spare cords. Visit the Glas Col site and get the model number for those mantles.
BTW just because the bottles are pyrex and have ST stoppers does not mean they are designed to be heated. Most likely they are thick and cast and will
crack if heated. The mantles were probably for cylindrical reactors like resin reactors, rather than bottles. Are the bottles Corning? If so read
Corning catalog and see if they can be heated. I'd advise not.
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chemrox
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Thanks for those cautions, I will certainly take a look at them. I may shelve those mantles for awhile.
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dedalus
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| Quote: | Originally posted by Sauron
No, Glas Col does not make or sell variacs, but the use of a variac as a controller is still common.
In this country the Glas Col agents are nice people while the Cole Parmer agents, and sometimes Cole Parmer itself, sometimes have their heads up
their asses.
I agree with you completely about Glas Col's profusion of plug types. In addition to male vs female grounds (center posts) a lot of older Glas Col
mantles are ungrounded especially fabric types. |
Sure, you can use a Variac on any heating device, it just varies the voltage. Using one in conjunction with one of the solid state controllers might
be a problem. I think those work via an "on/off" FET circuit device.
Cole Parmer...heh, heh! I once bought a pH meter off of them, decided that I wanted the next better model, and arranged with them to send back just
the meter. They sent me a whole new kit including a free $90 pH probe.
What a bunch of waterheads.
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not_important
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Most semiconductor based AC control devices use SCRs or TRIACs. For applications such as lamp dimming they usually turn on part way into a half cycle
of the AC, phase control. For heating control applications the controlled element has a much longer thermal time constant that a lamp filament and so
the controller turns on for X AC cycles or half cycles, and off for Y. The ones that 'count' full AC cycles are friendliest to the power source, as
they don't create a DC imbalance and don't put out much RFI which phase controllers do.
Simpler controllers as basically a set of contacts the are opened and closed by movement of a bimetallic thermometer, in effect a thermostat, that is
heated by a resistor across the controlled output.
There is an "infinity switch" used in audio control and effects that does use a FET. In this case it's controlling fairly low level AC analog signals
and can be thought of as an electronically controlled potentiometer.
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