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Information on proper usage of the distillation calculator applet

These two calculator applets will work with a simple pot still, such as the Alembic (or water sealed Alembic) stills found on:


or with the Alembic (or Water sealed Alembic) using the optional refining lentil.
NOTE using the refining lentil will produce a different characteristic distillation, and the application used to simulate them is different.

Some notes about these applications

a) The applets are simulations, which will be close, but may not exactly model a perticular still. Each still will have slightly different runtime characteristics, while this applet is designed to model a "generic" still.

b) The applets only model a binary liquid mixture of pure ethanol and pure water. However, fermented mashes contain other compounds, which will vary from recipe to recipe. Thus modeling only H2O and EtOH produces a close, but not exact match.

c) The applets do not try to guess where to stop collecting the heads and where to switch to the body within a run. This will be learned from experience of the distiller.

d) The Alembic applet does allow the distiller to state where to stop collecting the body, and to start collecting the tails. The applet can not guess these values, and where this cutoff happens can only be learned from experience of the distiller.

e) The Refining Lentil applet does not compute any tails. There may be some low grade ethanol left in the boiler after a distillation run with the lentil, and there may be benefits to continue distillation of this to capture this ethanol, however, the applet does not compute for this.

The applet's input fields are:

Alcohol Content

This data should be filled in with the percent strength (% ABV) of the wash you are about to distill. Valid starting mash strength can be between 1% and 90%.

The alcohol strength of the wash can be easily computed, if you know your starting and final specific gravities (SG) - measure these with a hydrometer (Our Mustimeter Item 4996 is a very high qualitytool to perform this task).
The % alcohol is (Starting - Final) x 129. eg: if your sugar/water mix starts with a SG=1.090 and when it completes, it drops to 0.980, then you end up with a wash (1.090-0.990) x 129 = 12.9%.

Starting SG
Ending SG
Wash is % alcohol

Some winemakers use the Ebulliometer degree table for their wines - it estimates the difference between the boiling point of their wine & distilled water (eg if your distilled water boils at 100C, and the wine boils at 93°C, then it has 8.8% alcohol). The following calc based on data from Churchward (ACI Jnrl & Proc, Jan 1940), supplied by Duncan.
NOTE that some correction may required if there is still residual sugar present. This calc is only good for % alcohol less than 25%.

When alcohol is %
Your wash should boil °C below that of distilled water

Volume of Wash

Enter the simple volume of the wash which is being distilled in this specific run. If you have more mash than can be distilled at one time, then ONLY enter the amount of wash which you will be placing into the boiler on a single run. You can enter this volume in liters(by selecting the proper radio button), or in US gallons (by chosing the other button).

Selection of US gallons will only impact the input. The US gallons input data will be converted into liters and used internally (all math in the applet is based upon liter volume). Also the output will be in mL (1000th liter) units. This applet will only allow volumes between 1L and 4000L (or .25 to 1000 us gallons).

Be SURE to input the actual volume of the wash, and NOT the rated volume of the still

Initial Temperature

This should be the starting temperature of the wash (select Celcius or Faranheit scales).

The starting wash temp can be between 1°C and 95°C (or 34°F to 200°F). Whicheven temperature scale is selected for the input scale will also be used as the scale in the output tables (or text).

Heat-up Power

This is the power used in bringing the wash in the still up to a boil. Select the power units in BTUs, Watts, or in Kilo-Joules.
NOTE that the heatup-power, and the distillation power will both need to be input in the same units. The power must be in the range of 100W to 99,999W (360 to 359996 KJoules or 342 to 341210 BTUs)

If you are using a gas, coal or steam heat source, and are unsure of the amount of power, one method to find this power, is to use the application, filling in the Alcohol Content / Volume of Wash and Initial Temperature with proper values, then guessing at the the Heat-up Power, and adjusting this value, until the "Heatup Time" for the main boil is the actual amount of time it takes to bring the boiler to a boil.

Once that Heatup Time value is correct, then you should have the proper power amount for your heat input source. Then, if you do not change the heat amount when switching into distill mode, you will also know the proper heat level for that input field.

Distillation Power

This is the amount of power (in W/BTU/KJ) which the actually distillation process proceeds at.

NOTE this does not have to be the same amount of power as used to initially bring the mash up to boiling temperatures.

%Internal Reflux

NOTE this item may be removed in the future, or changed to "% power loss" (which is more accurately what it is.)

The amount of time will be increased based upon this value. It is most useful when working with a "known" rated electric heater. Thus, if a heater is rated at 2500W, but in an actual run, the heatup time and the output rates are modeled "better" with 2250W power input, then the value of this field should be set to 10%, and the power should be set to 2500W.
NOTE at this time, this field will ONLY impact the run time power rating, and will NOT impact the heatup time. However, if changed to a "% power loss", then the applet will also be changed so that the heatup time will also take into account this field.
NOTE This variable is not part of the Refining Lentil applet. The refining lentil has it's own reflux computations.

Main Run Time-steps , Main Run Max-Time , Tail Run Time-steps

These are the time fields for the applet to work with. The three of them work together and their relationships will be explained here.

Distillation is a "continuious" process. That means that it is nearly impossible to model the exact state of the still for a full run. This applet works by computing how the still is running at the start and end of a short timeframe (time steps). We can fairly easily compute what changes have happened and what the still has done during the current time step (say over a 10 minute time frame). Thus we can know what the outputs were at the start of this 10 minute time frame, and can compute what the results were at the end of this timeframe, and then output them at the end of this timeframe (which is also the start of the next time frame).

When setting up a run, the amount of time you use for a time-step usually should be set as about 1/10 to 1/15 of the total expected run time for this distillation (NOT including the collection of tails). Then you should put this value (the 1/10th to 1/15th) into the Main Run Time-steps field, and put the expected run time into the Main Run Max-Time field. If zero (0) is entered into the Tail Run Time-steps field, then the applet will not compute tails time. The applet will auto compute tails, until there is very little alcohol left behind in the boiler. If collecting tails, it is best to set the Tail Run Time-steps field to an amount where 10 to 12 tails steps are output. Then it you will have information on where you should actually cut off tails collection (as the applet may want to distill for too much time).

The applet will not allow a main run to have more than 50 steps, and will also stop outputting tails data when more than 50 output steps are observed (with a warning message listing tails may not have completed).

Output in text only (no tables):

If this value is not checked, then the applet will put data into a tabular format (a set of painted grids).
If this value is checked, then the data will not be shown in a grid, but will be shown as formatted text.
The contents of the data are the same, it is just a different output format.

Compute Still Run Properties

Click on this button to take your data input, and display in a set of tables, or in a formatted text output. As you are changing data in the above input fields, the changes are NOT displayed until this button is clicked.

Also, after this button is clicked (and run data is being displayed), a clickable link will be added below the button. This link will take the data which is being shown, and will generate a popup page which is minimal text, and is very easy to properly print.

Show computed data in an easy to print popup window

This link will be displayed after the "compute" button was clicked. If this link is clicked on, it will generate a plain easily printable text page, that contains all of the data computed in a formatted manner.

The applet's output fields

Heatup Time 58

This is the amount of time required for raising the mash from the initial temperature provided, to a boiling temperature, with the amount of power being provided. This time will be based upon boiling power, %ABV of the wash, initial temperature of the wash, and volume of the wash.
(NOTE the 58 shown on this help page is just an example. The actual time will be computed, and based upon what values you have entered)


This is the time at the end of a "time-step". Thus, this field will be 10, 20, 30... if the time step value was set to 10 minutes.

Boil Temp

This is the temperature (in °F or °C) of the boiling mash within the boiler pot.

Vapor Temp

This is the temperature which the vapor being produced condenses at. It should be the observed temperature at the high point within the still head.


This is the volume of liquid collected during this time frame, and ONLY in this timeframe.


This is ABV purity of liquid collected during this time frame, and ONLY in this timeframe.

T. Collected

This is the total volume of collected product (or collected tails) since the start of the run (or start of the tails collection, if we are in the tails collection table).

T. Purity

This is the total %ABV of collected product (or collected tails) since the start of the run (or start of the tails collection, if we are in the tails collection table).

*** Summary of Distillation ***

This is a nice additional "section" which simply accumulates all of the above data, into a final form, computes all of the time step's data into a single finished value, and then shows that value.

The data shown is for:

a) The wash prior to the run
b) The main run
c) The tails run (optional)
d) The backset left in the boiler

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