Positive and Negative Pressure Laboratories: How to Protect Experimental Safety and Precision with Air Pressure Differences?

1. The Scientific Principles of Air Pressure Control

1. Positive Pressure Laboratory: The "Protective Shield" Against External Contamination

The positive pressure laboratory continuously inputs efficiently filtered air into the room through the air supply system, maintaining the indoor air pressureslightly higher than the outside(usually maintained at +10~+30Pa). This positive pressure difference creates an "airflow barrier" that prevents unfiltered external air from entering the room through gaps in doors and windows or personnel passages, thereby ensuring the cleanliness of the experimental environment.

Core Objective: To prevent external contaminants (such as dust, microorganisms, aerosols, etc.) from interfering with experiments, suitable for scenarios with extremely high cleanliness requirements.

2. Negative Pressure Laboratory: The "Safety Chamber" That Locks in Hazardous Substances

The negative pressure laboratory actively removes indoor air through the exhaust system, making the air pressurelower than the external environment(usually -15~-30Pa). The negative pressure difference ensures that potential indoor contaminants (such as viruses, toxic gases, radioactive particles, etc.) cannot escape, and all airflows are discharged after high-efficiency filtration or harmless treatment.

Core Objective: To protect the external environment and personnel safety, preventing the spread of harmful substances.

2. Application Scenarios: Essential Choices for Different Industries

Typical Applications of Positive Pressure Laboratories

1. Microelectronics and Chip Manufacturing
   Particles of 0.5 microns in the air can cause short circuits in chip circuits. The positive pressure environment combined with HEPA/ULPA filters can control cleanliness at ISO Class 1-5, meeting the needs of nanoscale production.

2. Aseptic Workshop for Biopharmaceuticals
   Drug filling, vaccine production, and other processes require cleanliness levels of hundreds or even higher, and the positive pressure system prevents microbial contamination.

3. Precision Instrument Calibration Laboratory
   Fluctuations in temperature, humidity, and particulate matter can affect the accuracy of optical instruments, balances, and other equipment, and the positive pressure environment provides stable conditions.

Essential Fields for Negative Pressure Laboratories

1. Research on Highly Pathogenic Pathogens (BSL-3/4 Laboratories)
   Research on Ebola, COVID-19, and other viruses must be conducted in a negative pressure environment, and all exhaust must undergo dual HEPA filtration or high-temperature inactivation.

2. Chemical Toxicology Laboratory
   Volatile toxic reagents (such as cyanides, aromatic compounds) must be collected and treated through a negative pressure exhaust system.

3. Nuclear Radiation Experimental Area
   Radioactive dust is controlled by negative pressure airflow to prevent diffusion to public areas.

3. Core Design Elements: From Theory to Practice

1. Precision of the Air Pressure Control System

• Dynamic Balance Design: The air supply and exhaust volumes must match in real-time. For example, in a positive pressure laboratory, the airflow must automatically compensate to maintain stable air pressure when personnel enter and exit.

• Redundant Backup: Key fans and control systems must be equipped with backup power to avoid pressure loss due to power outages.

2. Air Filtration Levels

• Positive Pressure Laboratory: Typically uses primary + medium + HEPA three-stage filtration, and ULPA (Ultra-Low Penetration Air) filters must be added when cleanliness requirements are extremely high.

• Negative Pressure Laboratory: The exhaust end must be equipped with high-efficiency filtration devices (such as BIBO bag-in-bag-out systems) to ensure zero leakage of harmful substances.

3. Building Structure Sealing

• Doors and windows are designed to be airtight, with silicone sealing strips filling the seams.

• Pass-through windows and interlocking door designs reduce pressure fluctuations, such as buffer rooms where double doors do not open simultaneously.

4. Intelligent Monitoring System

• Real-time display of indoor and outdoor pressure differences, temperature and humidity, particle concentration, and other data.

• Abnormal situations (such as pressure imbalance, filter blockage) trigger audible and visual alarms and automatically initiate emergency plans.

4. Operation and Maintenance Management: Balancing Safety and Costs

1. Energy Consumption Optimization

• Positive pressure laboratories have high energy consumption due to continuous air supply, and variable frequency fans and heat recovery devices (such as rotary heat exchangers) can be used to reduce operating costs.

• Negative pressure laboratories need to regularly test exhaust filtration efficiency to avoid increased energy consumption due to increased filter resistance.

Energy Recovery Devices

2. Personnel Operation Specifications

• Positive Pressure Laboratory: Cleanroom clothing must be worn before entering, and surface particles must be removed through an air shower.

• Negative Pressure Laboratory: Experimental personnel must wear protective equipment, and must go through a chemical shower or airlock room when exiting.

3. Regular Verification and Certification

• At least once a year, third-party testing is required to verify whether pressure differences, cleanliness, airflow organization, and other parameters meet ISO 14644, GMP, or biosafety standards.

5. How to Choose Laboratory Type? Key Decision Factors

1. Risk Assessment First

   • Does the experimental subject have infectious, toxic, or radioactive properties?

   • If the risk is outward > inward, choose negative pressure; if the risk is inward > outward, choose positive pressure.

2. Industry Compliance Requirements

   • For example, vaccine production must comply with the positive pressure requirements for A/B clean areas in GMP Appendix 1 (2023 new version);

   • The laboratory of the CDC must meet the negative pressure standards of the "Technical Specifications for the Construction of Biological Safety Laboratories" (GB 50346).

3. Long-term cost considerations

   • The operational and maintenance costs of negative pressure laboratories are usually higher than those of positive pressure laboratories (due to higher levels of exhaust treatment requirements).

The original text is empty.

6. Future Trends: Intelligence and Modularity

With the development of technology, laboratory air pressure control is evolving in two directions:

• AI Dynamic Regulation: Through sensor networks and machine learning algorithms, real-time optimization of air supply and exhaust strategies can achieve energy savings of over 30%.

• Rapid Deployment Solutions: Containerized negative pressure laboratories were widely used during the pandemic and may become standard for emergency research in the future.

Automatic Control Systems

The essence of positive and negative pressure laboratories is to solve complex safety and cleanliness requirements through the simple and efficient physical means of "pressure difference". Whether protecting experimental samples from contamination or safeguarding public health from threats, scientific design and rigorous management are the keys to success. As a professional service provider in the field of laboratory construction,Nanjing Expansion Technologyis committed to providing customers with one-stop solutions from planning and design to certification, allowing technological exploration to continue in a safe and controllable environment.