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A Brief Discussion on the General Requirements for Equipment Spacing in Dust-Free Workshops
2025/12/2
Therefore, the core of the design for equipment spacing is to ensure smooth airflow, avoid 33 vortices, and effectively carry away particles. Specifically, it needs to be determined comprehensively in combination with the airflow direction (vertical/horizontal laminar flow), equipment dimensions (height, width, length), and airflow parameters. The following is the detailed design logic and method:
First, clarify the airflow characteristics of the Class 100 cleanroom
The core of a dust-free workshop is unidirectional flow (laminar flow). The airflow moves at a uniform speed in a single direction (vertical laminar flow: from top to bottom; horizontal laminar flow: along the horizontal direction), and particles are carried away by the continuous replacement of air. The equipment spacing should meet the requirement of "not interfering with the laminar flow path", that is, the flow velocity and direction of the airflow around the equipment should be consistent with the mainstream (deviation ≤20%), and there should be no obvious vortices.
Ii. Design of equipment spacing for vertical laminar flow (airflow from top to bottom)
In vertical laminar flow, the airflow exits from the ceiling high-efficiency filter, flows vertically downward through the working area, and returns through the ground return air outlet. The height of the equipment, the distance between the top and the ceiling, and the lateral width are the key influencing factors.
The distance between the top of the equipment and the ceiling
If the height of the equipment is close to the ceiling, it will directly block the downward flow of the airflow above, resulting in the formation of an "airflow shadow area" (dead zone) at the top of the equipment.
The distance between the top of the equipment and the ceiling should be ≥300mm (conventional value). If the height of the equipment exceeds 2.5m (close to the ceiling height, the clear height of a general cleanroom is 3-4m), the distance should be increased to more than 500mm to ensure that the airflow can smoothly pass through the gap between the top of the equipment and the ceiling.
Exception: If the equipment is low (height < 1m), the distance between the top and the ceiling can be appropriately reduced, but it is necessary to ensure that the air flow velocity above the equipment is ≥ 80% of the main flow velocity (0.25-0.5m/s).
2. The lateral spacing between the devices (perpendicular to the airflow direction)
If the lateral spacing of the equipment is too small, it will cause a sudden drop in the flow velocity of the air between the equipment gaps, and particles are prone to deposition. If the spacing is too large, it will waste space.
Core principle: Ensure that the flow velocity of the airflow in the equipment gap is ≥ 80% of the main flow velocity to avoid particle deposition due to excessively low flow velocity.
Empirical value: The spacing should be ≥ half of the maximum lateral width of the equipment (for example, if the equipment is 1m wide, the spacing should be ≥500mm). If the equipment is of an irregular shape (such as with protruding parts), the "widest part" should be used for calculation.
3. The distance between the equipment and the wall/return air outlet
Equipment and walls: Walls are prone to accumulate dust. If equipment is too close to the wall, the gap will be too small, and the airflow cannot wash the area between the wall and the equipment, creating dead corners. It is recommended that the spacing be ≥500mm (minimum no less than 300mm).
Equipment and return air outlets: If the equipment is close to the return air outlet, it may block the backflow of air, causing local air pressure imbalance. It is recommended that the edge of the equipment be no less than 1000mm away from the return air outlet to ensure that the return air flow is not blocked.
Iii. Design of equipment spacing for horizontal laminar flow (airflow along the horizontal direction)
In horizontal laminar flow, the airflow flows horizontally (such as from the left wall to the right wall) and returns through the opposite return air outlet. The length, width and height of the equipment along the airflow direction are crucial, and it is necessary to avoid blocking the horizontal airflow path.
The spacing of the equipment along the direction of the airflow (longitudinal spacing)
If the distance between the tail of the previous device and the head of the subsequent one is too small along the direction of the airflow, it will cause the airflow to "circle" between the devices, forming vortices.
Core principle: Ensure that the airflow can pass through the equipment gap in a "straight line" without obvious detour.
Empirical value: The spacing is ≥ 1/3 of the length of the equipment along the airflow direction (for example, if the equipment is 3m long along the airflow direction, the spacing is ≥1m). If the surface of the equipment is irregular (such as with protruding pipes), an additional 50-100mm should be added according to the "longest protruding part".
2. The spacing of the equipment perpendicular to the airflow direction (lateral spacing)
The lateral spacing should ensure that the horizontal airflow can cover both sides of the equipment to avoid dead corners on the sides of the equipment.
Suggestion: The spacing should be no less than half of the width of the equipment perpendicular to the airflow direction (for example, if the equipment is 2m wide, the spacing should be no less than 1m). At the same time, it is necessary to ensure that the flow velocity of the airflow in the transverse gap is no less than 70% of the main flow velocity (as the flow velocity at the edge of the horizontal laminar flow is slightly lower than that at the center).
3. Height limit of the equipment
The effective height of the air flow layer in horizontal laminar flow is usually 2 to 3 meters (from the ground upwards). If the equipment height exceeds this range, it will "cut" the air flow layer, causing the upper air flow to be unable to reach the lower one, resulting in an imbalance between the upper and lower air flows.
Requirement: The height of the equipment ≤ the height of the horizontal air flow layer (usually ≤2.5m); If super high-rise equipment (such as over 3 meters) needs to be placed, an airflow channel of ≥500mm should be reserved on the top of the equipment (which needs to be verified by CFD simulation).
Iv. Adjustment of Spacing for Special Equipment
Heat-generating equipment (such as ovens, motors
Heating can cause local hot air currents to rise (vertical laminar flow) or shift laterally (horizontal laminar flow), interfering with the stability of laminar flow.
Adjustment: The spacing should be increased by 20% to 30% compared to the conventional value (for example, the conventional spacing is 500mm, and for heat-generating equipment, it should be 600 to 650mm). At the same time, ensure that the distance between the equipment and the return air outlet is ≥1500mm to accelerate the discharge of the heat dissipation airflow.
2. Dust-generating equipment (such as cutting and grinding equipment
Dust-generating equipment needs to quickly carry away particles through air flow to prevent particle diffusion.
Adjustment: The distance around the equipment should be increased to 1.5 times the conventional value, and a "buffer zone" (≥1000mm) should be reserved along the direction of the airflow (below in vertical laminar flow and downstream in horizontal laminar flow) to ensure that the particles are carried away by the airflow and do not spread to other areas.
V. Verification and Optimization: CFD Simulation is indispensable
Empirical values are only the basis. The actual design needs to be verified through computational fluid dynamics (CFD) simulation.
Simulate the airflow velocity field and pressure field of the equipment at different intervals, and observe whether there are vortices (areas with flow velocity < 0.1m/s) and dead corners (areas with particle residence time > 10s).
Based on the simulation results, fine-tune the spacing (such as reducing the spacing in the vortex zone and increasing the spacing in the velocity drop zone), and ultimately ensure that the airflow velocity in more than 90% of the areas around the equipment is ≥ 70% of the mainstream velocity.
Summary: Core parameter reference
Through the above design, the interference of equipment size on the airflow in the Class 100 cleanroom can be effectively avoided, maintaining a stable clean environment.
