Pressure difference control in pharmaceutical cleanrooms is crucial for ensuring drug quality, directly impacting the success of production validation and overall quality and safety. Room airtightness is a key prerequisite for establishing pressure difference, requiring coordinated management throughout the entire process from design, construction, commissioning, validation, and operation and maintenance. Key points are summarized below:
Pharmaceutical HVAC systems have strict requirements for parameters such as temperature, humidity, and pressure difference. Establishing pressure difference is the most challenging aspect, requiring deep collaboration between architectural and HVAC professionals.
During the design phase, the sealing of holes in the color steel panels must be selected according to airtightness requirements: workshops with high pressure difference requirements should use through-wall sleeves; active or vaccine workshops require high-sealing airlocks; areas with lower requirements can use decorative covers. Doors and windows should use fixed double-glazed windows and cleanroom doors, equipped with door closers to ensure sealing. When using high-speed roller shutters for logistics airlocks, the pressure difference should not exceed 20 Pa; otherwise, the door panels need to be reinforced. Normally closed plate-type smoke exhaust outlets should be selected, and the HVAC design should allow for a larger supply and exhaust air volume margin based on airtightness requirements.
During the construction phase, strict control of sealing quality is required: The color steel panels for the walls should use centrally placed aluminum or male-female groove connections; high-airtightness workshops require internal and external sealing; the ceiling and wall panels should use a ceiling-over-wall panel method, with gaps treated with rounded corner decorative strips; construction layout deviation must be ≤2‰; cleanroom door gaps must meet national standards, and wear-resistant and corrosion-resistant sweeping strips should be installed; the floor flatness must meet a deviation of ≤2-3mm when measured with a 2m straightedge to prevent air leakage through door gaps.
During the commissioning phase, a plan should be developed first, and airflow balancing should be performed using professional instruments. Air leakage losses should be compensated by adjusting valves or fan frequency. Stability should be tested by continuous operation for 24-48 hours; pressure difference fluctuation must be ≤10% of the set value. The control logic should be optimized, using a PID algorithm to improve response speed; dual sensors can be added to the buffer room to ensure accuracy. During the verification phase, simulated production disturbance conditions should be implemented, with data continuously collected at a frequency of ≥1 time/s. The system can only pass after three successful tests.
During the operational phase, a comprehensive maintenance system needs to be established: real-time monitoring through a remote monitoring system, setting tiered alarms, monthly inspections of sealing points, quarterly comprehensive testing, and semi-annual calibration of VAV valves and sensors; regular testing of airtightness using differential pressure attenuation or tracer gas methods, and establishment of trend records; and holding a special meeting every six months to optimize the system and introduce new technologies to improve control levels.
In summary, differential pressure control in pharmaceutical cleanrooms requires multi-disciplinary collaboration and strict control of airtightness and system stability throughout the entire process to avoid quality risks such as cross-contamination and ensure production compliance.
Suzhou Pharma Machinery Co.,Ltd.
2026/02/27
Icey
