Turn your still into a barometer!

[Maritimer]

When going for azeo, the important figure you are looking for is 78.2°C or 172.8°F. Sometimes the alcholometer reads azeo but the temperature is off. This is caused by the barometric pressure.

I don't bother with the parrot anymore because I know I'm getting azeo, but that weird temperature anomoly is bothersome.

So, check out the calculator on this site: http://www.trimen.pl/witek/calculators/calculators.html" onclick="window.open(this.href);return false;" rel="nofollow
and click on the Boiling Point Calculator on the left.

What you are presented with is a calculator that gives you the boiling point (and vapour temperature) of various liquids. To use it with ethanol, click on the Choose button and select ethanol.

In Canada, we measure pressure in kilo Pascals, kPa, and temperature in Celsius. The calculator as presented only works in Celcius, but it will work with any pressure measurement system. It seems that in Poland, which is where the calculator is from, pressure is measured in hecto Pascals, hPa.

So, I modified the calculator for our purposes. As is, it chops off the decimal parts of the temperature and pressure you want to use, so I changed the temperature and pressure boxes to read to one or two decimal places. In the USA, it seems that pressure is measured in inches of mercury and temperature in Fahrenheit, so I made a second calculator for you guys.

Here are the modified calculators:

BOILING POINT CALCULATOR C.zip

BOILING POINT CALCULATOR F.zip

Now, to use the calculator, you need to put in the normal boiling temperatures and pressures of ethanol.

For Celsius, that would be 101.3 kPa or 1013 hPa for the pressure, and 78.2°C for the temperature.

For the USA, 29.92 in Hg for the pressure and 172.8°F for the temperature.

You don't need to Choose the liquid; I've changed the default to ethanol.

So, now enter the temperature you are getting from what you think is your azeo. Look up the barometric pressure from the local weather bureau and see if it agrees.

If you are at sea level, all is OK, you can use the value calculated. If you are at a higher elevation, you'll need to compensate.

Say you are at 1000 feet and the weather bureau says the pressure at sea level is 30.00 inches of mercury. (If the weather bureau gives the pressure at your altitude, just use that.) The temperature outdoors is 50°F. The table shows that at 1000 feet, the pressure should be decreased by 0.106 in Hg, so at 1000 feet, the pressure is actually 30.00 - 0.106 = 29.894 in Hg. If you are producing azeo, this is what the calculator should show (approximately, don't get carried away with unwarranted precision).

From http://www.csgnetwork.com/barcorrectbcalc.html" onclick="window.open(this.href);return false;" rel="nofollow :

Code: Select all

Correction For Elevation In Inches Hg
Per 1000 Foot Difference In Elevation

To be added to barometer readings when above the datum plane or
subtracted from barometer readings when below the datum plane. 

Altitude
ft                       Temperature, °F
         0      10     20     30    40     50     60     70     80     90
0      .122   .119   .117   .114   .112   .110   .108   .106   .104   .102
1000   .118   .115   .113   .110   .108   .106   .104   .102   .100   .098
2000   .113   .110   .108   .106   .104   .102   .100   .098   .096   .094
3000   .108   .106   .104   .102   .100   .098   .096   .094   .092   .090
4000   .104   .102   .100   .098   .096   .094   .092   .090   .088   .086
5000   .100   .098   .096   .094   .092   .090   .088   .086   .084   .082
6000   .096   .094   .092   .090   .088   .086   .084   .082   .081   .080
7000   .093   .091   .089   .087   .085   .084   .082   .080   .079   .078

Well, that's enough for now. If you can find a similar chart for correction in metric, please let me know.

M