temperature calibration

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jdpete
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temperature calibration

Post by jdpete » Tue Jan 08, 2008 6:33 pm

Just completed my reflux still (offset) and distilled some water to do a test run. The vapor temperature in the column stabilized at 203.6F with reflux valve wide open. I have 30" of copper mesh in the column. I need to calibrate the thermometer. Can I use the vapor temperature as a reference for adjustment or will it be different than the actual temperature? The boiling point of water at my barometric pressure and altitude should be 209F.

new_moonshiner
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Post by new_moonshiner » Tue Jan 08, 2008 6:41 pm

I would just boil some water and cal to that .. I myself dont really try to get it dead on the biggest thing i use a thermometer for is the temp changes thats the most important. its better to have a good sensitive thermometer . that is more useful that one thats dead on and responds slow. after a few runs ya may not even pay alot of attention to it anyways ..

tracker0945
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Post by tracker0945 » Tue Jan 08, 2008 6:52 pm

As nm said, don't worry so much about accuracy as temp readings will vary quite widely with different stills or placement position. It is much more important to be able to notice temp fluctuations ie rises or falls as you run your unit.
For this reason, stick it in some boiled water and adjust to that, it will be close enough, 1 or 2 degrees or even a bit more will mean nothing in the long run.
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jdpete
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Post by jdpete » Tue Jan 08, 2008 7:20 pm

Just noticed some of the water I distilled left a little bit of oily substance on the side of the collection container. I wonder if I should have added some vinager to the boil to help clean?

new_moonshiner
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Post by new_moonshiner » Tue Jan 08, 2008 7:28 pm

that most likely came from the copper mesh if it was new .. the cleaning run (test run) should have cleaned it up fine..unless there is just something out of the norm.

HookLine
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Post by HookLine » Tue Jan 08, 2008 7:59 pm

Copper mesh usually comes coated with vegetable oil to prevent oxidation. A quick wash in warm soapy water, followed by a good rinse, before putting in the column is all that is needed.
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jdpete
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Post by jdpete » Wed Jan 09, 2008 11:56 am

One other thing I noticed is the temperature on the vapor above the packing stayed around 80F even though the water was about at boiling and then it shot up to 200F within like 10 seconds. Is the packing to tight? I surely did not think I packed it that tight.

frikz
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Post by frikz » Wed Jan 09, 2008 1:07 pm

When the water hasn't quite reached it's boiling point, there is little vapor formed and the head temperature remains low. If it really starts to boil, temperature rises quickly so I guess it's normal. Compare it with a whistling kettle if you like.

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