SMDmax an Entrainment Nozzle

Wash more. Entrain less.

Introducing the SMDmax™. Take your VDU to the next level.

smdmax product in use

Lechler developed the new SMDmax™ full cone spray nozzle specifically for entrainment-sensitive spray applications. This nozzle produces significantly coarser droplets than traditional spray nozzles used in entrainment sensitive applications. Moreover, the state of the art Lechler SMDmax™ technology is also entirely machined, which helps achieve a high-tolerance surface finish inside and out, producing consistent performance every single time.

Traditional free passage style nozzles designs allow for maximum water droplet distribution for the application. However, this design can cause the water droplets to pull ambient air along the nozzle when spraying out, increasing the velocity of the air and causing a lower pressure around the nozzle tip in a process called entrainment.

For certain water nozzle applications, entraining more air is ideal when wanting to create a powerful jet of water. Yet for free flowing nozzles, this increase of entrainment leads to varying water droplet sizes and unpredictable spray distribution. The SMDmax nozzle from Lechler lessens the entrainment and improves the spray performance for the application.


  • Allows for significantly lower entrainment across a wider operating range
  • Ideal for use in moderate to high C-factor columns
  • Largest free passage among all axial full cone nozzle designs commercially available
  • Axial orientation ensures the nozzle is self-draining
  • High-tolerance machined surfaces inside and out
  • Consistent performance due to a constant R-value of 0.5 at all pressures
  • Currently available only in 317L Stainless Steel*



  • Vacuum Distillation Columns
  • Packing Wash
  • Distillation tray spray distributors
benefits of the smdmax

Benefits of an Air Entrainment Nozzle

The major issue with entrainment is the unpredictability of the low pressure zone created around the base of the nozzle. This pressure can quickly draw in the ambient air and change the velocity of the ejected water or other fluid to an unpredictable 5 meters per second (m/s) to 10 m/s spray velocity. Also, the introduction of more air can atomize the water to form smaller droplets than is wanted for the application.

Entrainment sensitive technology such as the SMDmax nozzle takes the possible issues of entrainment into account by reducing the low pressure zone that is created around the nozzle base. This innovative design provides more predictable and controllable fluid dispersion. The velocity is reduced down to 4m/s to 7m/s for the fluid spray, ensuring that the water droplet sizes remain consistent across the entire spray application. The SMDmax water nozzle design also allows the application to receive larger droplet sizes for washing and distillation applications.

Applications & Uses for the SMDmax

The SMDmax can be used for applications where you want larger water droplets at a consistent spray range. Common applications include vacuum distillation columns, distillation tray spray distributors, and packing wash processes.

Vacuum distillation columns distill mixtures and solvents by using lower pressure to impact the fluids that have different vapor pressures. By reducing the pressure to lower than the vapor pressure present in the mixture, it creates a vacuum that allows for evaporation of any substance that has lower vapor pressure properties. The SMDmax muzzle works well in this environment due to the lower entrainment when there is low pressure already present in the application.

Distillation tray spray distributors separate water streams and turn them into vapor using trays and a reboiler. SMDmax nozzles eject the water onto the trays as the vapor passes through the trays without the fluid stream becoming impacted by the lower pressures that are present in the application. The nozzles allow the water to be evenly distrusted along the tray to allow for more vapor dispersion.

Packing wash applications require water to be evenly distributed to wash out any particulates. SMDmax nozzles spray cleaning liquids to evenly cover the surface in large, coarse droplets that can remove any grime and other sediments. Due to the coarser droplets, it can perform effective cleaning without requiring higher velocities.

Free Passage Style Nozzles vs Our SMDmax

Traditional free passage nozzles have a narrow diameter inlet and a wide orifice to allow water droplets to freely be released onto the application. However, the narrow diameter of the inlet creates the lower pressure zone that draws the air toward the orifice and interacts with the water stream. This interaction can cause varying velocities of the water droplets and can create an uneven distribution of droplets.

Lechler's SMDmax nozzles have the same interior design as traditional free passage nozzles. Along the outside of the nozzle, we eliminate the lower pressure zone to prevent the entrainment of air into the ejected spray. By offering high-tolerance machining along the inside and outside of the nozzle, you can gain lower entrainment along the entire operating range, consistent performance, and the largest free passage of fluids.

For more information about our air entrainment nozzles and SMDmax products, contact Lechler today.

Suggested Literature

SMDmax™ Data Sheet