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Which industries require GMP cleanrooms?
2025-03-14
Horizotal Laminar Flow Bench vs. Vertical Laminar Flow Bench: Key Differences
Laminar flow cabinet/ultra-clean bench is designed to create partial clean areas in order to meet the needs of modernized industrialization, including, photoelectric industry, bio-pharmaceutical and scientific research and other fields.It absorbs air through the pre-filter, which will then be pressurized into static pressure box and through the hepa filter. The purified will be supplied to the work area in vertical or horizontal airflow as required, so that the operating area reaches class 100 /ISO5 cleanliness. Laminar flow bench/ultra-clean bench is widely used in lithium, semiconductor, pharmaceutical, cosmetics, food and other industries that need clean environment to ensure production quality
Working principle of laminar flow cabinet/ultra-clean bench
Laminar flow cabinet/ultra-clean bench predictably sweeps particles in a uniform direction to the work area by purified airflow that is pressurized by small centrifugal fan and through two-stage filters (pre filter and HEPA filter), creating a sterile and dust-proof work environment.
Laminar flow cabinet/ultra-clean bench
Most of them are in ISO5/class 100, mainly divided into two categories, horizontal laminar flow hood and vertical laminar flow hood. According to the operation structure, it can be divided into unilateral operation and bilateral operation. According to its purpose, it can be divided into ordinary ultra-clean bench and biological ultra-clean bench.
Note: A clean bench is different from a Biological Safety Cabinet. The ultra-clean bench can only protect the reagents or samples operated in the work bench from pollution, and does not protect the operators, while the biosafety cabinet is a negative pressure system, which can effectively protect the operators.The following sections will help you understand the differences between horizontal and vertical laminar flow hoods and help you make a more reasonable choice for your cleanroom requirements.
Horizontal laminar flow bench/ laminar flow hood/ laminar flow cabinet/laminar flow chamber
The horizontal laminar hood, by its name, is able to blow air horizontally. Filters cover the back of the work area, and during work, air filtered by a HEPA filter (HEPA) or ULPA filter (ULPA) blows horizontal airflow and moves parallel to the face surface toward the operator until the air leaves the laminar hood housing.
Advantages:
1. Because both the inlet and outlet air flow of horizontal laminar hood are in the horizontal direction, the air flow direction does not need to be changed in the working area, so the air flow movement is closer to the ideal laminar flow state, and the turbulence on the working surface is minimum;
2. Since the air supply area is located on the back of the working area, products and materials can be closer to the filter;
3. Hands and gloves are almost free of contamination as the horizontal airflow passes through the working area before going to the operator.
Disadvantages:
1. As the horizontal airflow passes through the workspace first, it contaminates everything downstream of the airflow;
2. Since the HEPA filter needs to fully cover the back of the work area, the manufacturing cost will increase significantly with the increase of the height and size of the work.
The specifications of horizontal laminar flow bench are shown in the table below:
Vertical laminar flow bench/laminar flow hood/ laminar flow cabinet/laminar flow chamber
Inlet airflow and outlet airflow of vertical laminar flow is perpendicular. The filter is arranged above the work area, and during the working process, the clean air filtered by the high-efficiency filter (HEPA filter) or ultra-high efficiency filter (ULPA filtration ) is blown vertically downwards, onto the surface of the work area, and finally disperses to the outside environment.
Advantages:
1. Since the airflow blows vertically down to the surface of the working area and will not blow to the operator, the security of the operator is improved;
2. Because the filter is arranged above the working area, the area of the air inlet and the air outlet of the airflow has nothing to do with the available height space inside the equipment, it can adapt to larger products and materials by simply raising the height, which greatly increases the flexibility and lower the costs;
3. As there is no horizontal airflow, it can reduce the cross-contamination of materials on the working surface;
Disadvantages:
1. Since the airflow blows vertically downwards to the surface of the working area, when the airflow is too strong, the rebound airflow will be generated due to the inertial impact of the airflow, and then local turbulence will be formed, which will destroy the airflow laminar characteristics of the airflow;
2. When the product or material is stacked, it will obstruct the airflow.
The specifications of vertical laminar flow bench are shown in the table below:
Which laminar flow bench/clean bench is right for your application?
Whether it is a horizontal laminar flow bench or a vertical laminar flow bench, it can be used in lithium batteries, semiconductors, pharmaceuticals, cosmetics, food and other industries that need a clean environment to ensure production quality. However, in some cases, one of them will better suit your demands.
The following factors are usually considered when choosing a horizontal laminar flow bench or a vertical laminar flow bench: the location of the process, the form of the operation, the design of the working surface, the size of the material, and the safety of the operator. Therefore, in case of low cleanliness requirements or small amount of contaminants, we often choose vertical laminar flow benches. When minimal turbulence on the working surface is required, or where there are strict requirements for cleanliness and high requirements for contaminant control, a horizontal laminar flow bench will be the a better choice.
The following table shows the advantages and disadvantages of vertical laminar flow bench and horizontal laminar flow bench for your better reference and choice:
|
Vertical laminar flow chamber |
Horizontal laminar flow chamber |
|
The fan and filters are located in the ceiling |
The fan and filters are located inside the ceiling, but there is extra depth at the rear to allow air to re-enter |
|
Flow direction is downward (top to bottom) |
Flow direction is back to front (horizontal) |
|
More turbulence |
Reduced turbulence in the airflow |
|
The working height can be adapted to large equipment |
Low working height (compared to vertical laminar flow cabinet) |
|
There is less cross-contamination between samples placed on the work surface |
Since the airflow is horizontal, there is less risk of contamination of hands and gloves |
|
If using solder powder or fine powder, it is best to use a vertical laminar air flow hood |
Suitable for harmless powders and odors |
|
Since the flow is vertical, the pollution control is not very strict |
With a horizontal stream, contamination control can be quite strict because all components are located downstream of the sample |
|
Requires less floor space and the hood is not too deep |
More floor space and additional rear depth are needed for air reentry |
|
Contaminants will not be blown to user's face, increasing user safety |
Since the airflow is horizontal, contaminants may be blown onto the user's face – It is important to keep the sash and make the stool at the optimal height |
Based on the table above, what other factors should be taken into account in advance?
When choosing between horizontal and vertical laminar flow hoods, you must consider the nature of the work and the specific requirements of the experiment.
A horizontal configuration is ideal when you need to minimize turbulence near the work surface or when you need to work with small samples. When the limit of pollution is your priority, horizontal laminar hood is the best choice.
On the other hand, if there is a concern about the safety of the user when touching the sample, it is best to use a vertical laminar flow hood. This can be an important consideration if your work involves powders or produces welding fumes.
Additionally, if you need to place equipment such as a spin coater or UV ozone cleaner inside the hood, the vertical airflow will maintain laminar flow around those devices.
Both vertical and horizontal laminar flow hoods can maintain a clean environment, allowing you to conduct sensitive experiments. However, there are subtle differences between the two types that will determine the right laminar hood configuration for you.
More other considerations?
Some final considerations involving vertical and horizontal laminar flow hoods:
1) In the presence of a biological hazard, neither vertical nor horizontal laminar flow hoods are applicable. In applications requiring biosafety level (BSL) 2 or 3 protection, only approved containment systems, such as Class II, Type A2 biological safety cabinets, should be used.
2) Whichever laminar flow hood design you choose, make sure to run it for at least 15 minutes before starting critical operations to remove particles from the housing.
3) Every time you clean the cabinet, remember the sweeping direction from clean to dirty. Start at the surface of the filter and move downstream along the airflow to wipe the surface in a smooth, linear motion. Perform "dirty" operations as far away from the filter as possible, such as unpacking a sample.
