I wasn't able to find specific documentation on determining the number of HEPA air filtration units needed for a 40 cubic meter room to achieve 4 air changes per hour in our current safety knowledge base, but here are industry-standard safety guidelines:

To determine the number of HEPA air filtration units needed, you'll need to consider the following factors:

1. Room Volume: You've specified a 40 cubic meter room. 2. Air Changes Per Hour (ACH): You want to achieve 4 ACH. 3. HEPA Filter Unit Capacity: Determine the cubic meters per hour (m³/h) or cubic feet per minute (CFM) that each HEPA unit can filter. This information should be available in the product specifications.

Here's a general approach to calculate the required number of HEPA units:

• Calculate the required airflow rate:
• Required airflow (m³/h) = Room volume (m³) x ACH
• Required airflow (m³/h) = 40 m³ x 4 ACH = 160 m³/h
• Determine the number of HEPA units:
• Number of units = Required airflow (m³/h) / HEPA unit capacity (m³/h)

For example, if each HEPA filter unit has a capacity of 80 m³/h:

• Number of units = 160 m³/h / 80 m³/h = 2 units

Therefore, you would need 2 HEPA filter units with a capacity of 80 m³/h to achieve 4 ACH in a 40 cubic meter room.

Additional Considerations:

• Filter Efficiency: Ensure the HEPA filters meet the required efficiency standards for capturing particles of concern.
• Placement: Strategically place the HEPA units to ensure adequate air circulation throughout the room. Avoid obstructions that could impede airflow.
• Maintenance: Regularly maintain the HEPA units, including filter replacement, to ensure optimal performance.
• Noise: Consider the noise level of the HEPA units, especially in occupied spaces.
• Airflow Patterns: Evaluate the existing ventilation system and airflow patterns in the room to optimize the placement and number of HEPA units.

By following these guidelines, you can determine the appropriate number of HEPA air filtration units needed to achieve the desired air changes per hour and maintain adequate ventilation and air quality compliance.