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Head temperature - reflux still

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  • trebor0898
    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
    Message 1 of 11 , Jul 31 1:47 AM
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      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).
    • Dean Thomas
      Many of the more expensive probes still have + or - 1 degree. All you can do is make sure that your probe is sticking in far enough to be in the alcohol path
      Message 2 of 11 , Jul 31 2:28 PM
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        Many of the more expensive probes still have + or - 1 degree. All you
        can do is make sure that your probe is sticking in far enough to be in
        the alcohol path and if that is the case I wouldn't dwell on it to much.
        The main thing you're looking for is consistency and definite
        temperature change points and you've found both. Besides you cant get
        much better than 95%.

        Dean.

        trebor0898 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).
        >
        >
      • go_stiller
        Hi Rob from OZ Mine varies depending on which still I use from 76.2 to 77.3. I have very accurate thermo couples. With a long column the head temp is cooler, I
        Message 3 of 11 , Jul 31 2:56 PM
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          Hi Rob from OZ
          Mine varies depending on which still I use from 76.2 to 77.3.
          I have very accurate thermo couples. With a long column the head temp
          is cooler, I started with small column and the temp was steady on
          77.3, now with longer column 76.2. This varies with power that is
          applied as with high vapour speed the temp in the top of column goes
          up, but the quality goes down. This is only valid for long columns as
          short column already have fast vapour speed and higher head temp. You
          are doing everything right the temp variation is what you need to look
          for.
          JW


          > 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).
        • Garry Patten
          I wouldn t worry about it to much mate. Mine always sits just under 78 and i always average around 95%. Your getting good stuff so must be working ok. Cheers
          Message 4 of 11 , Aug 1, 2005
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            I wouldn't worry about it to much mate. Mine always sits just under 78 and i always average around 95%. Your getting good stuff so must be working ok.
            Cheers
            Garry.

            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).







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          • Mark
            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. (If you re
            Message 5 of 11 , Aug 1, 2005
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              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.

              (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....)

              +/- 1 deg C is ok for common commercial units. Lab grade stuff is
              usually +/- 0.1 deg C. And you can buy calibrated equipment that is
              even more accurate. 2 deg C is a bit much.

              Just a thought - are you sure the thermocouple and the display are
              the same "type"? There are type "J" thermocouples, type "K"
              thermocouples, type "T", type .... well, there's about 7 different
              types. J is the most common. K is common also. Using a "J" in
              a "K" unit (or vice versa) won't read accurately.

              But like another response said - it's the temp change that needs
              watched. Watch the temp, and when you are suspect of the product
              quality, switch bottles or sample the product cut to 50%abv in a
              shot glass.


              --- 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).
            • 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 6 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.
                >
                > 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.
                > ________________________________
                >
              • 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 7 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 8 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 9 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 10 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
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
                        >
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                        >
                        > ---------------------------------
                        > 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 11 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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