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 sweeps away airborne particles.

Laminar flow hoods operate on the principle of laminar airflow, where a stream of air moves in a uniform direction with minimal turbulence. The air is usually 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 to maintain a clean and particle-free environment within the hood.

Types of Laminar Flow Hoods

Horizontal Air Hoods: These hoods have a horizontal airflow pattern, where the filtered air moves horizontally across the work surface, providing protection for the materials or processes placed on it.

Vertical Air Hoods: In vertical air hoods, the filtered air flows vertically from the top of the hood downward onto the work area. This configuration is commonly used for applications involving hazardous materials, as the vertical flow helps to contain any potential contaminants more effectively.

Biological Safety Cabinets (BSCs): BSCs are a type of air hood designed specifically 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 the safety of the personnel involved.

Laminar hoods are subject to several safety and regulatory standards, depending on the specific 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 in 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 utilized in pharmaceutical production facilities, hospitals, and clinics for activities like compounding sterile drugs, handling sensitive medical devices, and performing aseptic procedures.
Electronics and Manufacturing: Laminar hoods are employed in electronics assembly and manufacturing industries to protect sensitive components from dust, particulates, and static electricity.
Cleanrooms: In cleanroom environments, clean benches are used to 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:

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

Differential pressure sensors are essential in laminar flow hoods, enabling the monitoring, control, and maintenance of the airflow and pressure levels necessary for a controlled and 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 family has an extremely low noise floor resulting in the industry’s highest levels of accuracy, steadiest long-term stability and lowest error rates.

The HV Series’ wide dynamic range is ideally suited to provide multiple pressure ranges in a single package, thus minimizing the number of sensor variants required to support the diverse requirements of laminar flow hoods. The HV has a selectable bandwidth filter from 0.1Hz to 10Hz, and up to 19-bit effective resolution. For added performance, the HV Series has an integrated 50/60Hz notch filter to minimize 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 one device. And these sensors support pressure ranges as low as 25 pascals. Power on time is also a consideration and with warm‐up in the range of just a few minutes, the HV Series is an excellent choice for time critical installation applications.