What Is A Dephlegmator (And How Do They Work?)

Image of diy distilling what is a dephlegmator and how does it work

Distillation of alcohol has been around for hundreds of years, dating back as far as the 12th century. The processes have dramatically changed over the years, and a lot of that has to do with the distilling hardware being used.

Distillation is used in the production of wine, whisky, vodka, and other spirits. Distillation can also be used in the petroleum industry to purify crude oil into refined fuel. This article will focus on the distillation of alcohol, the practices, processes, and applications.

Is distillation a chemical or physical reaction?

The process of distillation is a physical change due to the liquid being converted to vapor, and then back to liquid. These properties are physical changes and do not involve chemical reactions. In some instances, a chemical reaction may occur during certain incidences. This generally occurs in a large-scale distribution facility.  

There are 3 main steps when distilling alcohol:

Step 1: The conversion of a liquid mixture into the form of vapor by heating the liquid at high temperatures.

Step 2: The condensation of the purified liquid after high temperatures have turned the liquid into vapor.

Step 3: The collection of the condensed liquid after the process of conversion.

Types of stills:

Pot Still

A pot still is a large spherical chamber with a swan-style neck and a lyne arm protruding in the form of a spout. The arm feeds into a coiled condenser and into the collection chamber. These types of stills have been around much longer and are a lot simpler than that of the column still. A pot still is almost entirely made out of copper material as it is an excellent conductor of heat and is an easy metal to work with. Using a pot still, the wash (beginning liquid) is heated up in the main chamber. This used to be done by heat sources like fire, but advancements have brought safer techniques such as temperature-controlled steam. Once the wash is heated until boiling ethanol vapor rises, the vapor exits via the lyne arm. The vapor then passes through a cooling coil where it is condensed as a liquid into the collection chamber.

Column Still

A column still is a more industrial application in the process of distillation. Column stills are generally much taller, more vertical, and contain several chambers stacked on top of each other. Column stills are manufactured out of stainless steel, copper, or a combination of the two. A column still works like a series of pot stills stacked on top of each other. Using a column still, the heat source used is steam and it is already present inside the still. The steam runs through the base of the many chambers and to the top of the still. The wash ( beginning liquid) enters the top of the column and begins to sink down into the other chambers in a liquid form. As ethanol heats and evaporates, it rises through the chambers, re-evaporating and condensing at every stage. In each chamber, ethanol will lose impurities such as water and ingredients before it reaches the top of the still in pure form. The ethanol vapor then exists, passing through cooling condensers and into a collection chamber.

What is a dephlegmator?

A dephlegmator (also referred to as a reflux condenser) is an attachment device used in distillery practices of a column still. It is built into the top of a distillation column. Many distillers and production facilities today are using stills equipped with a dephlegmator. The addition of a dephlegmator provides supplemental reflux capacity for optimal distilling processes. 

Image of diy distilling what is a dephlegmator and how does it work image

How do you pronounce dephlegmator?

Dephlegmator is pronounced with the phonetic spelling “de-phleg-ma-tor”.

What is reflux?

Reflux is the result of condensed vapor within the column being returned to either the plates or wash within the column that provides supplementary reflux power. A well-refined product will be dependent on the amount of reflux. The more frequently alcohol becomes vaporized, travels up the columns, and becomes knocked out by reflux components before being released from the still, the more refined the product becomes. Complete reflux means no vapor is released from the still and continues being cycled through the columns.

How does a dephlegmator work?

A dephlegmator is composed of several tiny, plumed tubes that, when turned on, fill with cold water, and create a chilling surface on which alcohol will condense, bead up, and fall back down into the column. The majority of dephlegmator stills are equipped with multiple plates within a column. These plates permit the vapor to pass through from below but trap vapor descending from above to create more reflux.

How do you use a dephlegmator?

To use a dephlegmator, you will need to install the component at the top of a still. The dephlegmator coil will need to be hooked up to a cool water supply. When the dephlegmator is turned on, water will begin to circulate through the coil in a regulated practice to achieve reflux. The dephlegmator will cycle until the desired level of reflux has been achieved.

What Type Of Dephlegmator Do You Need?

Here is a few considerations when selecting the right type of dephlegmator for your needs.


A dephlegmator is typically made out of copper or stainless steel with pros and cons for each.

  • Copper: Better thermal conductivity which means you can often get away with a smaller physical size. Higher cost. Better looking! Quickly oxidizes and must be cleaned more frequently.
  • Stainless Steel: Poorer thermal performance but cheaper. Stronger and more durable. Stays bright and shiny longer.

Size and Dimensions

  • Length: The length of a dephlegmator varies. A general dephlegmator with a 3-inch diameter will be around 6 inches tall.
  • Diameter: The average dephlegmator is between 3-4 inches in diameter. 

Cooling tubes

The quantity of cooling tubes often varies with the diameter for the dephlegmator. For example, a 4inch dephlegmator will typically have 7 barrels while a 2-inch will have 3.

Dephlegmator DiameterCooling Tubes (Typical)

The diameter of the cooling tubes is approximately 5/8 inches but can vary depending on the diameter of the dephlegmator.

Frequently asked questions

Q. What temperature of cooling water is best for a dephlegmator?

Optimal water temperatures for a dephlegmator are between 160-170 degrees Fahrenheit. 

Q. What direction does water flow in a dephlegmator?

The water in a dephlegmator flows clockwise in a regulated, continuous loop.

Q. Where does a dephlegmator go?

A dephlegmator is installed on the top of a column still.

The practice and process of distillation should be done in a monitored setting with all safety procedures and precautions set in place. Distilling can be a dangerous process if not handled and done correctly. In some places, the distillation of alcohol in your own home can be legal if it is done correctly and safely for all parties involved. For more information on distillation and the process of how it works, check out Home Distiller. Org.

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