Glossary of Vacuum Terms and Phrases

Following is a brief glossary of commonly used terms related to vacuum distillation.

Closed Loop Temperature Control –

Method where the temperature is constantly measured and output signal sent to control process to maintain a constant temperature

Cold Trap –

A vessel designed to hold a refrigerant, inserted into a vacuum system so as to remove condensable vapors present. In these stills, the cold trap consists of an outer shell or vacuum housing with an internal refrigerant reservoir.

Degasser –

A chamber that prepares material by removing a portion that will evaporate at room or low temperatures when subjected to a vacuum environment and is often used to preheat material before molecular distillation.

Degassing – 

The removal of dissolved gas (e.g. air moisture, etc.) from raw feedstock, usually under vacuum and by application of heat. (See Stripping).

Desolventation –

The removal of volatile liquid (e.g. solvents, etc.) from the feed material. (See Stripping).

Distilland –

The material to be processed in a distillation. (See Feedstock, Raw Feedstock).

Distillate –

The portion of the feed material which is vaporized from the still rotor and is condensed back to liquid.

Distillation –

The process of separating a component or substances from a liquid by selective evaporation and condensation. Distillation may result in a partial separation that increases the concentration of selected components of the mixture.

Distillation Pressure –

The pressure (Vacuum in Torr, Barr or other vacuum measurement units) that the chamber is maintained at during distillation.

Feedstock –

(Also feed material, feed). Degassed or stripped raw feedstock for processing on a still.

Flat Gasket –

A gasket made from flat stock (e.g. rubber sheet).

L-Ring Gasket – 

A molded circular gasket of L-shaped cross section fitting over the outside and lower edge of bell jars or unflanged glass cylinders.

Micro of Mercury –

A unit of pressure equal to 1/1000th of one millimeter of mercury pressure. Abbreviated as u of Hg. or uHg.  (See Torr).

Millimeter of Mercury –

A Unit of Pressure. At standard conditions, one atmosphere of pressure equals 760 mm Hg. This means that if one end of a tube is immersed in Hg. and a vacuum applied to the other end, the Hg will rise in the tube to a height of 760 mm. The pressure unit, 1 mm Hg absolute, is 1/760 of an atmosphere.

Molecular Distillation –

vacuum distillation below the pressure of 0.01 torr. It is a process of separation, purification and concentration of natural products, complex and thermally sensitive molecules for example vitamins and polyunsaturated fatty acids.

O-Ring Gasket –

A circular cross-section made to specific dimensional tolerances.

Pass –

A pass is one complete movement of the feedstock through the still.

Raw Feedstock –

Feed material which contains moisture, dissolved gases, solvents or other material in any combination which is not desired in the molecular distillation process.

Refrigerant Reservoir –

The container of a cold trap in which the refrigerant is held.

Residence Time –

The average time material spends in a given location, in molecular distillation this is most often referred to as the time on heated surface.

Resistance Time –

The time that a product is in contact with heated surface

Residue –

The portion of the feedstock which is not vaporized from the still rotor, but remains liquid after passing over the rotor, and is collected in the residue gutter.

Short Path Distillation

– Short path distillation is defined as distance between heating element and condenser being equal to or less than the mean free path ( distance a molecule can travel in a vacuum with out striking another molecule). This distance varies dependent on the vacuum pressure inside the chamber.

Stripping – 

Stripping involves removing (and usually recovering) volatiles from the raw feedstock. These volatiles usually amount to over 1% of the feedstock.

Thermal Separation –

Using different evaporation temperatures on mixed materials to separate. Example- heating mixture to evaporation one part of while staying below evaporation of second.

Torr –

A pressure unit. One Torr equals 1 mm Hg — 1 millitorr equals one micron Hg.

Ultimate Pressure –

The lowest pressure attainable in a given vacuum system.

Vacuum Configuration –

How vacuum components are located and type used to pump and measure a chamber

Vacuum Distillation –

Distillation of a product at reduced pressure ( Below Atmosphere). There-by reducing the temperatures required for a component of the product to evaporate. Reducing the possibility of thermal damage (scorching) of the product. Note : with some products evaporation takes place at room temperatures by just reducing pressure (Vacuum).

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