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Vertical vs Horizontal Laminar Flow Hood

Vertical vs Horizontal Laminar Flow Hood

Laminar flow hoods (LFHs) are essential tools used in scientific and industrial applications to create a controlled, clean environment. Within a laminar flow hood, filtered air moves in a smooth, unidirectional flow through the workspace. Sensitive experiments and processes are safeguarded from contamination by maintaining a particle-free zone.

Two main types, the vertical laminar flow hood and the horizontal laminar flow hood, are available. The difference between the vertical and horizontal configuration is the direction of air flow through the hood. Clean air will either flow horizontally or vertically, and each orientation has useful applications. Here, we compare both types of laminar flow hood, helping you decide which configuration is the right choice for your needs.

Neither vertical or horizontal laminar flow hoods are suitable for handling biohazardous or toxic samples.

Difference Between Horizontal and Vertical Laminar Flow Hoods

In horizontal laminar flow hoods, the filters are fixed to the back wall of the unit. Air is pulled from the back of the hood through the filter (usually a HEPA filter). The filtered air travels parallel to the work bench across the length of the hood and exits through the front opening.

In a vertical LFH, the filter is positioned on the top panel, moving air down towards the work bench. In a horizontal LFH, the filter is positioned on the back wall, moving air horizontally across the workspace.

Whereas, in a vertical laminar flow hood, the filtered air is directed vertically through the workspace. At the work bench, the air flow is redirected out of the front panel. In these hoods, the filters are on the top panel of the unit.

When to Choose a Horizontal Laminar Flow Hood

There are several advantages to choosing a horizontal laminar flow hood.


  • Placing your hands inside a horizontal LFH will not disrupt the laminar flow. The air flow travels parallel to the workbench and flows around your hands.
  • Contaminants introduced by hands or gloves are quickly removed from the workspace. In the vertical configuration, contamination on your gloves could be carried onto the samples underneath. This does not happen with horizontal air flow, so there is a low risk of the user contaminating the sample.
  • Low air turbulence near the work surface creates ideal clean air conditions for conducting workbench experiments or reactions.
Horizontal LFHs allow air to flow around a user's hands. In vertical LFHs, hands will interrupt air flow.

    However, there are also some downsides to using an LFH in the horizontal orientation.


    • Air flow, along with any contaminants, is directed towards the user. Even if working with non-hazardous materials, this can be uncomfortable or hazardous.
    • Large or bulky equipment can block the laminar air flow and reduce the hood effectiveness.
    • Risk of sample contamination from other items within the hood.
    • Harder to access and change filters than a vertical LFH.

    Generally, horizontal laminar flow hoods are best suited to simple worktop-based experiments which do not use hazardous materials, and where reducing contamination is a priority. Examples include media plate preparation, growing plant or mammal tissue cultures, small electronics inspection, or thin film deposition.

    When to Choose a Vertical Laminar Flow Hood

    Depending on the application, opting for a vertical laminar flow hood can be advantageous.


    • Large or bulky equipment will not interrupt the downward laminar flow. You can use larger equipment such as a spin coater, sonicator, or UV ozone cleaner with this configuration.
    • Air flow is not directed immediately into the room, which offers greater comfort and safety to the user.
    • Easier access for HEPA filter maintenance and replacement.
    • Reduced risk of cross contamination from other materials in the workspace. In horizontal LFHs, samples positioned at the front of the hood may be susceptible to contamination from materials at the back of the hood.
    • The useable workspace is maximized as the filters are positioned above the work bench.
    Large equipment does not interrupt air flow in vertical LFHs. In horizontal LFHs, the laminar air flow may be obstructed and disrupted by large equipment.

      There are also some limitations to consider before choosing a vertical laminar flow hood.


      • Placing your hands into the laminar flow hood can disrupt the air flow, reducing the effectiveness of the hood.
      • Air flow in a vertical LFH is more turbulent than in a horizontal LFH, especially at the workbench level.
      • Downward air flow can disturb smaller samples or open solutions in the workspace, as the air flow is aimed directly at the work bench.
      • Contaminants on your gloves or airborne particles can be carried onto samples on the work bench. The risk of user contamination is increased with a vertical air flow.

      Vertical laminar flow hoods are useful if you need to maintain low contamination levels, while using large or bulky equipment. They are also a good choice if you prefer more user protection. For example, if you are working with powders, the vertical configuration prevents materials from being blown directly at you. Some relevant uses for vertical LHFs include non-hazardous microbiological applications, large electronics inspections, and non-hazardous chemical reactions and procedures.

      Laminar Flow Hood

      Laminar Flow Hood

      Vertical vs Horizontal: Making the Choice

      When choosing between a horizontal and vertical laminar flow hood, you must consider the nature of your work and the specific requirements of your experiments. The horizontal configuration is ideal when you need minimal turbulence near the work surface or if you are working with small samples. They are most useful when limiting contamination is your main priority.

      On the other hand, a vertical laminar flow hood is preferable if there is any concern about the safety of the user being exposed to the samples. If your work involves powders or produces soldering fumes, this could be an important consideration. Additionally, if you need to place equipment such as a spin coater or UV ozone cleaner in the hood, a vertical air flow will maintain laminarity around this equipment.

      Both vertical and horizontal laminar flow hoods will maintain a clean environment in which you can conduct sensitive experiments. Yet, there are subtle distinctions between the two types which will determine the right laminar flow hood configuration for you.

      Contributing Authors

      Written by

      Dr. Mary O'Kane

      Application Scientist

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