In numerous cutting-edge fields such as electronic chip manufacturing, biomedical research and development, and high-end precision instrument production, dust-free clean rooms play an irreplaceable role in "providing safeguard". The constant and suitable air environment inside them is the key to ensuring product quality, process precision, and the health of personnel. And the fresh air volume and supply air volume are just like the "pulse" of this crucial system, so it is of vital importance to accurately control their values. As the professional Guangzhou Cleanroom Construction Co., Ltd., today we will take you to have an in-depth understanding of their calculation methods.

The oxygen consumption for the breathing of workers in the dust-free room is a fundamental factor to be considered when calculating the fresh air volume. Generally, an adult needs about 30 - 50 cubic meters of fresh air per hour. Suppose there are 20 workers on duty simultaneously in a clean room on a daily basis. Estimating the fresh air volume at 40 cubic meters per hour per person, at least 20 × 40 = 800 cubic meters per hour of fresh air is required in this area. This is to disperse the carbon dioxide exhaled by people, odors, and so on, maintain fresh air, and avoid discomfort such as dizziness and fatigue caused by lack of oxygen and dirty air among personnel, thus ensuring an efficient working state.

In order to prevent the unpurified air from the outside from "sneaking in", most dust-free clean rooms are maintained in a slightly positive pressure state. According to practice and industry standards, the pressure difference between clean rooms of different levels and adjacent lower-level or non-clean areas is between 5 - 20 Pascals. To achieve this positive pressure, it depends on the support of fresh air. Taking a common Class 100,000 clean room as an example, combined with the room volume and the airtightness of the enclosure structure, through complex formula conversions (air volume = air change rate × room volume, where the air change rate is set according to the empirical value for maintaining positive pressure), calculate the additional fresh air volume required to make up for the leakage through gaps and maintain positive pressure. Then add the fresh air volume for personnel breathing to get the complete fresh air requirement.

Some production processes will emit dust, hot air, and harmful gases, such as electronic welding fumes and chemical synthesis volatiles. Corresponding exhaust fans will continuously extract air. In order to balance the indoor air flow and air pressure, the fresh air volume needs to be supplemented equally or in excess of this part of the loss. If the process exhaust air volume is stable at 500 cubic meters per hour, the planning of the fresh air volume should reserve at least this value to prevent negative pressure from causing unclean air to flow back and contaminate the clean operation area.

The air change rate is a commonly used yardstick for calculating the supply air volume. Different purification level clean rooms have very different requirements for the air change rate: Class 100 (high-standard aseptic areas for biopharmaceutical production) often requires 500 - 600 times per hour; Class 10,000 clean rooms used for general electronic packaging are about 25 - 35 times per hour; Class 100,000 (most common electronic processing) is usually 15 - 20 times per hour. Given a Class 100,000 clean room for electronic component assembly with a length of 10 meters, a width of 8 meters, and a height of 3 meters and a volume of 240 cubic meters, according to an air change rate of 18 times per hour, the supply air volume is 240 × 18 = 4320 cubic meters per hour, ensuring efficient replacement of indoor air and timely discharge of dust particles.

In unidirectional flow clean rooms (such as the chip lithography area), the control of cross-sectional wind speed is of great significance. In order to stably carry dust towards the air outlet, industry regulations require that the cross-sectional wind speed of vertical unidirectional flow should be maintained at 0.3 - 0.5 meters per second, and that of horizontal unidirectional flow should be 0.2 - 0.4 meters per second. For example, in a vertical unidirectional flow clean room with a width of 5 meters and a height of 2.5 meters, to achieve a cross-sectional wind speed of 0.4 meters per second, according to the flow formula (air volume = cross-sectional wind speed × cross-sectional area), the supply air volume can be obtained as 0.4 × (5 × 2.5) × 3600 (converting seconds into hours) = 18,000 cubic meters per hour, realizing precise air flow organization and ensuring that key processes are not interfered by dust.

The operation of large equipment generates heat, which is the "culprit" for temperature fluctuations in clean rooms. In areas with intensive data center server cabinets and laser processing equipment, sufficient supply air volume is needed to dissipate heat and maintain a constant temperature. Through the heat dissipation power of the equipment and the allowable temperature rise range, combined with thermodynamic parameters such as the specific heat capacity of air, calculate the demand for cooling air flow and incorporate it into the planning of the supply air volume. If a single cabinet in a data center dissipates 3 kW of heat, according to the heat balance conversion, about 1000 cubic meters per hour of cold air is required. The supply air volume of the entire clean room should be adjusted according to the number of cabinets to ensure the stable operation of the equipment.

After mastering the essence of the calculation of fresh air volume and supply air volume, in actual operation, it is also necessary to adjust according to local conditions and in a dynamic manner. With the increase in the service life of clean rooms, the replacement of equipment, and the upgrading of processes, the air volume requirements often change. Guangzhou Cleanroom Construction Co., Ltd. is equipped with a professional technical team that is proficient not only in theoretical algorithms but also capable of on-site surveys, simulation and optimization. We will escort your projects from planning to operation and maintenance, customize clean air solutions for you, and help your dust-free clean rooms always maintain their "vitality" and meet the stringent requirements of industrial upgrading. If you are preparing a clean room project or are troubled by air volume problems, please feel free to contact us at any time!