Choosing between a Horizontal and Vertical Laminar Flow Cabinet

A Laminar Flow system plays a crucial role in controlling particulate contamination. It refers to a steady, uniform flow of air.

Inside the Laminar Flow Cabinet, the air initially passes through an easy-change, high-quality EU4 pre-filter, effectively removing larger particulate matter. Subsequently, the air is directed through the fan system and forced through an H15 ULPA filter that can eliminate 99.9998% of particles larger than 0.12 μm.  

By employing this setup, the system ensures an ISO Class 3 (FED Class 1) environment for Vertical Laminar Flow (VLF) and ISO Class 4 (FED Class 10) for Horizontal Laminar Flow (HLF).

These classifications create a particle-free workspace and offer optimal product protection. The cabinet is enclosed on three sides, maintaining a constant positive air pressure to prevent the intrusion of contaminated air.

Most contamination-sensitive environments require laminar flow as it directs particles uniformly from the cleanest area beneath the filter face to the exit area, usually the working aperture.

The design guarantees that the cleanest zone remains closest to the filter face, and work is predominantly performed within this clean area, away from obstructions that could cause turbulence.

VLF Cabinets are often chosen because they resemble the design of cleanrooms on a smaller scale, where fan/filter units are typically positioned in the ceiling. This downward laminar flow direction enhances the effect of gravity, effectively sweeping particles out of the enclosure, usually through a front access area.

Vertical flow expedites micro-contaminant settling, which may not have significant mass but will eventually settle on surfaces or the room floor.

A VLF Cabinet is generally deemed appropriate for sterile or particle-sensitive processes conducted in a clean, sterile zone between the work surface and the filter face. For example, sterile compounding procedures involve preparing injectable or sterile packages above the work surface.

Ensuring that hands and other contamination sources move up and down rather than sideways above a sample helps maintain the cleanliness of sensitive materials.

Considering the effects on operators, HLF, which directs air from the rear of the cabinet and exits through the front opening, may not encounter significant obstructions inside the cabinet.

It can, however, lead to substances, such as soldering fumes or fine powders, being blown toward the operator's face. While this may not compromise the laminar flow where the work is performed, it does pose potential health risks. In such cases, vertical flow is preferred as it provides greater protection for the operator.

Vertical laminar flow cabinets


  • Greater Operator Protection.
  • Cabinet not as deep: requires less floor/worktop space.
  • Suitable for compounding sterile products.
  • Safety: air will not blow directly at the operator and the sash provides a barrier.
  • Top mounted filter ensures easy access.
  • Less turbulence from air striking large objects or equipment.
  • Less cross-contamination of items positioned on the work surface.


  • Extended overhead clearance means changing filters or servicing may require a step ladder.
  • Cannot place items or hands on top of other items as this will obstruct airflow.
  • Increased turbulent effect of air striking the work surface.

Horizontal laminar flow hoods


  • Greater Product Protection.
  • Reduced turbulent effect of air striking work surface.
  • No sash: easier to work and position equipment, but air blows directly on the operator.
  • Hands and gloves are generally less contaminating since they’re downstream of the sample.


  • Large samples obstruct laminar air flow and may contaminate downstream samples.
  • Blows fumes and powders in the operator’s face.

About Monmouth Scientific Limited


At Monmouth Scientific environmentally responsible recirculating technology is the core of our expertise. 

Our specialised Fume Cupboard, Laminar Flow, Biological Safety, Powder Containment, and ISO Class Cleanroom solutions provide the best protection and performance for your personnel.

A UK Market Leader in Clean Air Solutions and at the forefront of the industry, we           employ cutting-edge technologies and innovative engineering, to ensure that our solutions consume minimal energy while delivering optimal performance.  

As experts in clean environments and laboratory personnel safety, our team continue to proudly pioneer innovative new technologies to guarantee the highest levels of safety for a diverse client base including; 

  • Laboratory
  • Research
  • Pharmaceutical
  • Electronics
  • Aerospace

Sponsored Content Policy: publishes articles and related content that may be derived from sources where we have existing commercial relationships, provided such content adds value to the core editorial ethos of News-Medical.Net which is to educate and inform site visitors interested in medical research, science, medical devices and treatments.

Last updated: Sep 8, 2023 at 5:16 AM


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