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Author: Subject: Thermometers and vaccums.
thunderfvck
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[*] posted on 24-2-2004 at 22:23
Thermometers and vaccums.


Thermometers. Did you order a nice one, or did you get a crappy one from the store? You know the kind, from 0 to 50C, pretty poor, not very useful for most things. So I'm wondering where most of you guys got yours...?

And vaccums! Always fun. WHat do YOU use as a vaccum source? I have read that compressors for refridgerators work well, anyone try this? Aspirators, anyone? I bought a little piece of crap aspirator that doesn't even fit on my sink. Very disappointing. I'm also concerned about the water backup that could become a problem with aspirators, so I'd like to get a real vaccum...

And that's about it. Thermometers and vaccums. Thanks.




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ech310n
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[*] posted on 25-2-2004 at 01:02


I have a thermometer I purchased from a lab supplier for about AU$10. It's red-spirit filled and can measure temperatures from -10*C to 110*C which is more than enough for my current needs. Many of the thermometers you buy from a local store are very inaccurate as learned from experience.

As for a vacumn source I don't have one as that is currently low on the priorities of what I would like. At the moment I am more interested in buying some books on chemistry to learn more :)

[Edited on 25-2-2004 by ech310n]




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axehandle
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[*] posted on 25-2-2004 at 04:32


My thermometer is bought from a lab supplier for about EUR15, it can measure from -10 to 250 centrigrades.

Also, I have two digital ones (probe + unit) for kitchen oven processes.

As for a vacuum source, I don't have one yet. I'm either going to buy an aspirator from a lab supplier, or cast the parts for a vane pump in brass and build it (they're very expensive to buy, yet very simple in operation).




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Tacho
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[*] posted on 25-2-2004 at 05:36


Usually you buy thermomethers. There is a wide range of them commercially available. I have a couple of precise mercury ones.

I have, however, built an electronic one. I did it from scrach and it's also a precise thermostat. I dont't think it's worthwhile unless you are in need of carefull temperature control and are skilled in electronics. I'll be glad to give details if you are interested.

Refrigerator pumps are limited to about 300 mmHg. I find that vacuum good enough for all my needs: vacuum filtration, vacuum drying and distillation.

They are CHEAP and you can find them everywhere. They don't last long, about 10 hours of use is my experience. Well, a filtration takes 1 min! Distillations seems to be their #1 enemy.

If I were you, I would get a refrigerator pump and see if it suits your needs.

There are many threads discussig pumps. Do a search.

You will find many people screaming that only a 0,0000000001 mTorr vacuum is good enough. I mean, in my opinion, there is exageration. Depends on what you are planning to do.
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[*] posted on 25-2-2004 at 11:27


Vacuum below 1mbar is going to demand lots of your equipment. Hermetically sealed joints and scratchless equipment, otherwise you'll be amused by a symphony of imploding glass.

PTFE membrane pumps which pull 160mbar can be had for ~300€, new.

No fuzz about oil and suckback and whatnot.




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