Pressure Sensors in Laminar Flow Hoods

What are Laminar Flow Hoods?

Laminar flow hoods, also known as clean benches, are specialized enclosures used in scientific applications and various industries to create a sterile working environment that can be monitored and controlled. Laminar hoods are designed to protect samples, products, or processes from contamination by providing a continuous flow of filtered air that removes airborne particles.

Laminar flow hoods operate on the principle of laminar airflow, in which a stream of air moves in a uniform direction with minimal turbulence. Air is typically drawn from the surrounding area, passed through high-efficiency particulate air (HEPA) filters, and then directed toward the work area in a unidirectional flow. This flow helps maintain a clean, particle-free environment within the hood.

Types of Laminar Flow Hoods

• Horizontal Air Hoods: These hoods feature a horizontal airflow pattern in which filtered air moves horizontally across the work surface, protecting the materials or processes on it.
• Vertical Air Hoods: In vertical air hoods, filtered air flows vertically from the top of the hood down onto the work area. This configuration is commonly used for applications involving hazardous materials because the vertical flow helps contain potential contaminants more effectively.
• Biological Safety Cabinets (BSCs): BSCs are air hoods designed for handling biological materials. They provide both product protection (via HEPA-filtered air) and personnel protection (via HEPA-filtered air and a physical barrier), preventing the release of harmful agents into the environment and ensuring personnel safety.

Laminar hoods are subject to various safety and regulatory standards, depending on the application and industry. Organizations such as the International Organization for Standardization (ISO) and the Centers for Disease Control and Prevention (CDC) provide guidelines and standards for the design, operation, and maintenance of clean benches and biological safety cabinets.

Applications for Laminar Flow Hoods

Laminar flow hoods are used across various industries and applications, including the following:

• Laboratories: Laminar hoods are widely used in research laboratories for processes such as cell culture, sample preparation, and microbiological work. They help maintain sterile conditions and prevent cross-contamination.
• Pharmaceutical and Medical Industries: Clean benches are used in pharmaceutical production facilities, hospitals, and clinics for activities such as compounding sterile drugs, handling sensitive medical devices, and performing aseptic procedures.
• Electronics and Manufacturing: Laminar hoods are used in electronics assembly and manufacturing to protect sensitive components from dust, particulates, and static electricity.
• Cleanrooms: In cleanroom environments, clean benches create localized areas of cleanliness within a larger controlled space, ensuring the integrity of critical processes and sensitive equipment.

The role of pressure sensors in laminar flow hoods

Differential pressure sensors are an important part of laminar flow hoods. Their use includes:

1. Monitoring Airflow: Differential pressure sensors measure the air pressure within the hood. They detect changes in pressure and provide feedback to the control system. By monitoring pressure, the sensors help ensure that the desired airflow velocity is maintained within the hood, which is critical for maintaining the cleanliness and sterility of the working area.
2. Maintaining Positive Pressure: In some applications, it is necessary to maintain positive pressure within the air hood. This means the air pressure inside the hood is higher than the ambient pressure outside. Positive pressure helps prevent contaminants from entering the hood by creating an outward flow of air. Differential pressure sensors monitor the pressure and trigger adjustments to the airflow if it drops below the desired level.
3. Ensuring Safety: Differential pressure sensors help ensure the safety of operators working in the environment. If the pressure drops significantly, indicating a potential failure or blockage in the ventilation system, the sensor can trigger alarms to alert operators and prevent hazards until the issue is resolved.
4. Calibration and Validation: Differential pressure sensors in laminar hoods are also used for calibration and validation. During installation and periodic maintenance, the sensors are checked and calibrated to ensure accuracy. This helps maintain the hood's reliability and effectiveness in delivering the required airflow and pressure conditions.

Differential pressure sensors are essential in laminar flow hoods, enabling the monitoring, control, and maintenance of airflow and pressure levels necessary for a controlled, contamination-free environment.

Superior Sensor Technology’s differential pressure sensors for air handling applications

Superior’s HV Series is a flexible line of differential pressure sensors for HVAC systems and air-handling applications. Consisting of four sensors, the HV Series has an extremely low noise floor, resulting in the industry’s highest levels of accuracy, the steadiest long-term stability, and the lowest error rates.

The HV Series’ wide dynamic range is ideally suited to provide multiple pressure ranges in a single package, minimizing the number of sensor variants required to support the diverse requirements of air hoods. The HV Series features a selectable bandwidth filter from 0.1 Hz to 10 Hz and up to 19-bit effective resolution. For added performance, the HV Series includes an integrated 50/60 Hz notch filter to minimize the impact of power noise spikes. Finally, optional integrated closed-loop control customization, advanced digital filtering, and a 3-mode pressure switch provide additional integration capabilities.

Superior’s unique Multi-Range technology enables the sensors to support up to 8 pressure ranges in a single device. These sensors also support pressure ranges as low as 25 pascals. Power-on time is also a consideration, and with warm-up in just a few minutes, the HV Series is an excellent choice for time-critical installation applications.

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