Short Path Evaporator
The evaporator for extraordinary applications

The SMS Short Path Evaporator with internal condenser has been mastering demanding thermal separation duties for more than 60 years.
The unique combination of evaporation and condensation in extreme proximity permits the operation of the Short Path Evaporator with a vacuum up to 0.001 mbar (a). This operating range is unchallenged by any other type of evaporator.


The benefits of SMS short path evaporators are obvious:

  • Minimum pressure drop permits high vacuum operation and low product temperatures
  • Gentle distillation of heat sensitive products with short residence times and minimum product hold-up in the evaporator
  • The special design of the Short Path Evaporator enables Molecular Distillation
  • Efficient droplet separation for outstanding distillate quality
Working principle of short path distillation
Cross section of short path evaporator

Basic Operating Principle

Short path distillation is a thermal separation technology operating at process pressures in the range of 1 to 0,001 mbar. It lowers the boiling temperature and is an excellent method for gentle thermal treatment of heat sensitive, high boiling products. The short path evaporator consist basically of a cylindrical body with a heating jacket, a rotor and an internal condenser.
The rotor creates a mechanically agitated, thin product film on the heating surface inside of the body. By means of gravity the product flows down in a spiral path, whereby the volatile portion of the product evaporates. The vapour passes by the shortest route and with practically no pressure drop to the internal condenser. The non-volatile portion reaches the lower part of the evaporator and is discharged through the bottom product outlet. The residual vapours and inert gases flow through the vacuum nozzle to the vacuum system.

Design Features of Short Path Evaporators

SMS Short Path Evaporators are available in a unique variety of rotor designs comprising:

  • PTFE or Graphite wiper elements
  • Spring loaded PTFE or wiper elements
  • Metal wiper elements
  • Polymer or Graphite rollers
  • Hygienic design

The rotors can be equipped with specially designed splash guards, protecting the internal condenser from droplets in the vapour stream and ensuring highest distillate quality.

The internal condenser can be removed from the bottom of the short path evaporator. The majority of the short path evapoarators is supplied with tubular condenser, but SMS has designed special thermoplate condensers to meet the hygienic requirements of the food and pharma industry.

Rotor with PTFE wiper elements
Short path evaporator rotor with metal wipers
Rotor with spring loaded wipers

Typical Applications

The short path evaporator is specifically well suited for distillation, evaporation, concentration and stripping of heat sensitive products as follows: