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Re: [Distillers] Head temperature - reflux still

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  • dearknarl
    Gday, Just for a second, assume the measuring device is accurate: Could the discrepancy be due to any cooling effects from your condenser? ie. falling reflux
    Message 1 of 11 , Aug 1, 2005
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      Gday,

      Just for a second, assume the measuring device is accurate:

      Could the discrepancy be due to any cooling effects from your
      condenser? ie. falling reflux or conduction through the mount point to
      the condenser or atmosphere?

      That's what I'd put my money on. How do you mount the probe, and where?

      Cheers,
      knarl.

      On 7/31/05, trebor0898 <rob@...> wrote:
      > Hi,
      >
      > This is my first post, so please be gentle.
      >
      > I have built a Nixon-Stone valved still, 2" dia and 6 feet (2m)
      > tall, it works beautifully, I get 95% all the time (neutral spirit),
      > heads are very short and basically no tails because the cut is so
      > definite.
      >
      > My design has been as a result of a lot of web research for which I
      > would like to thank the distilling community. My question is to do
      > with temperature. All of the litriture says 78.3 degrees C but mine
      > sits steady on 76.4 throught the whole run until it shoots to 80 in
      > seconds as the tails hit.
      >
      > This makes it easy to operate but I don't get it, I am using an
      > accurate digital probe and have compared it with a thermocouple. I
      > am virtually at sea level and the air presure normal. It seams to me
      > that 2 whole degrees (C) is a lot of difference.
      >
      > The probe is at the top of the column, no leaks and appears to be
      > independant of boiler heating power (within normal limits). The only
      > thing I can think of is that my column is TOO long.
      >
      > Does anyone have a comment.
      >
      > Thanks in advance,
      >
      > trebor0898 (Rob from OZ).
      >
      >
      >
      >
      >
      >
      >
      > Distillers list archives : http://archive.nnytech.net/
      > FAQ and other information at http://homedistiller.org
      >
      >
      > ________________________________
      > YAHOO! GROUPS LINKS
      >
      > Visit your group "Distillers" on the web.
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    • trebor0898
      Reflux enters below the probe as it is a valved offset head (like an H), so reflux is not cooling it down. The probe is at the top of the column extending down
      Message 2 of 11 , Aug 2, 2005
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        Reflux enters below the probe as it is a valved offset head (like an
        H), so reflux is not cooling it down. The probe is at the top of the
        column extending down level with the t-piece which directs the
        vapour over to the condensor side.

        I tend to agree with a number of replies that the column being so
        long (over 6 feet) has losses despite insulation. The measureing
        device is accurate to .01 as I have checked it.

        Rob..

        --- In Distillers@yahoogroups.com, dearknarl <dearknarl@g...> wrote:
        > Gday,
        >
        > Just for a second, assume the measuring device is accurate:
        >
        > Could the discrepancy be due to any cooling effects from your
        > condenser? ie. falling reflux or conduction through the mount
        point to
        > the condenser or atmosphere?
        >
        > That's what I'd put my money on. How do you mount the probe, and
        where?
        >
        > Cheers,
        > knarl.
        >
        > On 7/31/05, trebor0898 <rob@p...> wrote:
        > > Hi,
        > >
        > > This is my first post, so please be gentle.
        > >
        > > I have built a Nixon-Stone valved still, 2" dia and 6 feet (2m)
        > > tall, it works beautifully, I get 95% all the time (neutral
        spirit),
        > > heads are very short and basically no tails because the cut is
        so
        > > definite.
        > >
        > > My design has been as a result of a lot of web research for
        which I
        > > would like to thank the distilling community. My question is to
        do
        > > with temperature. All of the litriture says 78.3 degrees C but
        mine
        > > sits steady on 76.4 throught the whole run until it shoots to 80
        in
        > > seconds as the tails hit.
        > >
        > > This makes it easy to operate but I don't get it, I am using an
        > > accurate digital probe and have compared it with a thermocouple.
        I
        > > am virtually at sea level and the air presure normal. It seams
        to me
        > > that 2 whole degrees (C) is a lot of difference.
        > >
        > > The probe is at the top of the column, no leaks and appears to
        be
        > > independant of boiler heating power (within normal limits). The
        only
        > > thing I can think of is that my column is TOO long.
        > >
        > > Does anyone have a comment.
        > >
        > > Thanks in advance,
        > >
        > > trebor0898 (Rob from OZ).
        > >
        > >
        > >
        > >
        > >
        > >
        > >
        > > Distillers list archives : http://archive.nnytech.net/
        > > FAQ and other information at http://homedistiller.org
        > >
        > >
        > > ________________________________
        > > YAHOO! GROUPS LINKS
        > >
        > > Visit your group "Distillers" on the web.
        > >
        > > To unsubscribe from this group, send an email to:
        > > Distillers-unsubscribe@yahoogroups.com
        > >
        > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
        Service.
        > > ________________________________
        > >
      • Alex _{*L*}_ (a.k.a. BOKAKOB)
        This is a very *nice* point in advocating my policy of the thermometer placement not at the very top of the column but toward the lower end of the top third of
        Message 3 of 11 , Aug 2, 2005
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          This is a very *nice* point in advocating my policy of the thermometer placement not at the very top of the column but toward the lower end of the top third of the packing.

          There are a few more positive things which can be monitored with a single thermometer at lower location.

          See my writing "Mode Observations..." here http://tinyurl.com/17a



          dearknarl <dearknarl@...> wrote:
          Gday,

          Just for a second, assume the measuring device is accurate:

          Could the discrepancy be due to any cooling effects from your condenser? ie. falling reflux or conduction through the mount point to
          the condenser or atmosphere?
          That's what I'd put my money on. How do you mount the probe, and where? Cheers, knarl.


          Alex_{*L*}_(a.k.a. BOKAKOB)
          http://briefcase.yahoo.com/bokakob

























          ---------------------------------
          Start your day with Yahoo! - make it your home page

          [Non-text portions of this message have been removed]
        • Alex _{*L*}_ (a.k.a. BOKAKOB)
          See that the bottom of the thermometer is in the hot vapor pass. It also could be that the thermometer requires certain length of the probe to immersed in
          Message 4 of 11 , Aug 2, 2005
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            See that the bottom of the thermometer is in the hot vapor pass. It also could be that the thermometer requires certain length of the probe to immersed in measured medium. It it is *not* then it could be just ambient cooling since all hot vapors flow in the "elbow" to the right.... or to the left.

            By the way I know of *nothing* which can change evaporation temperature of alcohol or any pure substance except pressure. Not the length, not cooling, etc. etc.


            trebor0898 <rob@...> wrote:
            Reflux enters below the probe as it is a valved offset head (like an H), so reflux is not cooling it down. The probe is at the top of the
            column extending down level with the t-piece which directs the vapour over to the condensor side.
            I tend to agree with a number of replies that the column being so long (over 6 feet) has losses despite insulation. The measureing
            device is accurate to .01 as I have checked it.
            Rob..


            Alex_{*L*}_(a.k.a. BOKAKOB)
            http://briefcase.yahoo.com/bokakob
























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          • Willy
            Some things to ponder: all mentionned temperatures are right for certain conditions only. I m using very accurate thermometer and my headtemps are around
            Message 5 of 11 , Aug 2, 2005
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              Some things to ponder: all mentionned temperatures are right for
              certain conditions only. I'm using very accurate thermometer and my
              headtemps are around 71ºC; Water is boiling here at 91ºand a boiling
              water-ice mix is 44º.
              If one does his things in a place other than on sea-level, temps will
              change!
              By the way, I am living on a confortable height of 2600m asl (about
              9000F)and ad a good amount of sugar to my molasses and sugar-wash to
              get a little higher separationtemp. Out of neccessity i re-use most
              of this wash in my following batch, which means i am in the dunder
              job and with good results...

              will


              --- In Distillers@yahoogroups.com, "Alex _{*L*}_ \(a.k.a. BOKAKOB\)"
              <bokakob@y...> wrote:
              > This is a very *nice* point in advocating my policy of the
              thermometer placement not at the very top of the column but toward
              the lower end of the top third of the packing.
              >
              > There are a few more positive things which can be monitored with a
              single thermometer at lower location.
              >
              > See my writing "Mode Observations..." here http://tinyurl.com/17a
              >
              >
              >
              > dearknarl <dearknarl@g...> wrote:
              > Gday,
              >
              > Just for a second, assume the measuring device is accurate:
              >
              > Could the discrepancy be due to any cooling effects from your
              condenser? ie. falling reflux or conduction through the mount point to
              > the condenser or atmosphere?
              > That's what I'd put my money on. How do you mount the probe, and
              where? Cheers, knarl.
              >
              >
              > Alex_{*L*}_(a.k.a. BOKAKOB)
              > http://briefcase.yahoo.com/bokakob
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              > ---------------------------------
              > Start your day with Yahoo! - make it your home page
              >
              > [Non-text portions of this message have been removed]
            • Robert Hubble
              ... Mark and Rob from Oz, The degree of thermal isolation between the condenser and the head thermometer is an important factor in accuracy of apparent head
              Message 6 of 11 , Aug 2, 2005
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                >From: "Mark" <markgofast@...>
                >Reply-To: Distillers@yahoogroups.com
                >To: Distillers@yahoogroups.com
                >Subject: [Distillers] Re: Head temperature - reflux still
                >Date: Tue, 02 Aug 2005 02:50:45 -0000
                >
                >Check your probe in boiling water. Note the difference between 100
                >deg. C and what the unit displays. Use that number to correct your
                >still temps.

                Mark and Rob from Oz,

                The degree of thermal isolation between the condenser and the head
                thermometer is an important factor in accuracy of apparent head temperature.
                Of course, this is almost entirely dependent on still design. When
                initially testing my pot still, with all "upper plumbing" in copper with
                almost no thermal isolation, the head temp reading would drop 2 degrees C
                when condenser cooling water was turned on. This has to be due to the
                condenser sapping heat from the still head through the copper vapor pipe.

                Until I change the design, my temperature decisions are based relative
                temperatures.
                >
                >(If you're really anal like me, you'll do the same with a mixture of
                >ice and water in a thermos to see the temp. difference at 0 deg. C.
                >Then calculate / plot a temperature correction factor and ..... oh
                >screw it....)
                >
                ----snip----
                >
                >--- In Distillers@yahoogroups.com, "trebor0898" <rob@p...> wrote:
                >
                >My question is to do with temperature. All of the litriture says
                >78.3 degrees C but mine sits steady on 76.4 throught the whole run
                >until it shoots to 80 in seconds as the tails hit. It seams to me
                >that 2 whole degrees (C) is a lot of difference.
                >
                >Thanks in advance,
                >
                >trebor0898 (Rob from OZ).
                >
                >

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