Precision Control of Airflow: An In-Depth Application Guide to Nexisense Duct Air Velocity and Airflow Monitoring Technology

In modern industrial manufacturing, commercial building management, and environmental monitoring, precise airflow control is the cornerstone of production efficiency and environmental safety. Whether maintaining positive pressure in cleanrooms or ensuring compliant kitchen exhaust emissions, air velocity and airflow data inside ducts are the most critical reference indicators. Leveraging advanced sensing technology, Nexisense unveils the professional essence of duct air velocity monitoring.

Definition of Intelligent Airflow Monitoring: What Is a Duct Air Velocity Transmitter?

A duct air velocity transmitter is a precision instrument specifically designed to measure gas flow velocity inside enclosed ducts or air channels and convert physical signals into standard electrical signals. Unlike cup anemometers or ultrasonic anemometers used in open environments, duct-mounted sensors must operate within narrow spaces, withstand high-speed airflow, and handle potentially corrosive media.

The Nexisense duct air velocity transmitter integrates air velocity sensing and signal conversion modules, enabling real-time detection of subtle airflow fluctuations. It is purpose-built to provide high-accuracy, long-life online monitoring for HVAC systems, industrial dust collection, laboratory ventilation, and kitchen exhaust systems.

Hot-Film Anemometer: Complete Analysis of the Core Working Principle

Nexisense duct air velocity transmitters adopt advanced hot-film anemometer technology, which is the core solution for precise low air velocity measurement.

The operating principle is based on thermal balance. Inside the sensing probe, a heating element and a temperature-sensitive element are installed. When air flows across the probe, it carries away heat from the heating element. The higher the air velocity, the greater the heat loss. To maintain a constant temperature difference between the heating element and the ambient environment, the circuit automatically adjusts the compensation current. By measuring this compensation current and processing it through Nexisense’s independently developed full-range secondary calibration algorithm, the device outputs highly linear air velocity values.

This principle offers significant advantages: it can detect extremely low air velocities down to a few centimeters per second, maintain excellent repeatability at high flow rates, and eliminate mechanical wear due to the absence of moving parts.

Nexisense Device Structure Analysis: The Essence of Industrial-Grade Design

An outstanding sensor depends not only on its chip but also on its structural protection in harsh environments.

• High-temperature and corrosion-resistant housing: Nexisense uses specially formulated polymers or stainless steel protective materials to ensure measurement accuracy is not compromised by chemical corrosion in kitchen fumes or industrial exhaust environments.

• Dust-resistant probe rod: The probe rod is aerodynamically optimized to minimize disturbance to the original airflow field, while its surface treatment effectively prevents particle adhesion.

• Flange mounting system: Standard flange mounting with pre-drilled installation holes is used. High-quality silicone sealing rings fit the duct curvature perfectly, preventing pressure leakage, which is critical for accurate air pressure and air velocity measurement.

• Screwless terminal blocks: To accommodate complex on-site installation conditions, Nexisense adopts imported screwless terminals. Wiring is completed with a simple “press-and-insert” action, significantly improving installation efficiency and preventing loosening caused by vibration.

• EMC anti-interference design: The internal circuitry integrates dedicated electromagnetic compatibility (EMC) components, ensuring stable data even in environments with high-power frequency converters, motors, or elevator equipment.

  
  

From Air Velocity to Airflow: Automated Calculation Methods

In real-world engineering applications, users are often more concerned with the total volume of air passing through per unit time, known as “airflow.”

1. Calculation Formula

Airflow (L) refers to the volume of air passing through a duct per unit time. The commonly used calculation formula is:

L = F × V × 3600

Where:

• L represents airflow, typically expressed in cubic meters per hour (m³/h);

• F represents the duct cross-sectional area or effective ventilation area (m²);

• V represents the measured average air velocity (m/s).

2. Intelligent Software Processing

Manual conversion is time-consuming and error-prone. Nexisense provides dedicated configuration software. Users simply input the duct cross-sectional area, and the sensor automatically completes mathematical modeling. Through standard communication protocols, monitoring software can display both air velocity and airflow data in real time.

Application Scenarios: From Kitchen Exhaust to Industrial HVAC

1. Kitchen Exhaust and Oil Fume Monitoring

According to kitchen exhaust system design standards, duct air velocity is typically controlled between 8 m/s and 10 m/s. Installing Nexisense air velocity sensors downstream of exhaust fans enables real-time monitoring of fume direction and speed. When combined with oil fume concentration monitoring systems, managers can clearly determine purification equipment operating status and efficiency, ensuring environmental compliance.

2. HVAC Systems

In smart buildings, air velocity sensors are installed in main supply ducts and return air outlets. By monitoring air velocity, variable frequency fans can be dynamically adjusted to achieve on-demand air supply, significantly reducing building energy consumption.

3. Cleanrooms and Laboratories

In pharmaceutical and semiconductor industries, maintaining constant air change rates and slight positive pressure is mandatory. Nexisense captures subtle air velocity changes, providing front-end feedback for precision pressure control systems.

Core Technical Parameters Overview

• Power supply: 10–30V DC

• Air velocity range: 0–10 m/s, 0–15 m/s, 0–20 m/s (customizable)

• Accuracy: ±(0.2 + 2%V) m/s

• Operating temperature: -40°C to 80°C

• Communication protocol: Standard Modbus-RTU, supports secondary development

• Output signals: RS485, 4–20mA, or 0–10V optional

• Baud rate: Supports 2400, 4800, 9600, and more

• Protection rating: IP65 waterproof and dustproof

Installation, Maintenance, and Servicing: Keys to Long-Term Accuracy

1. Installation Guidelines

• Location selection: Install on straight duct sections. The distance from upstream bends, valves, or other resistance components should be 5–10 times the duct diameter, and 3–5 times downstream.

• Sealing treatment: After drilling and installation, ensure the silicone sealing ring is fully compressed to prevent localized air leakage and turbulence.

2. Routine Maintenance

• Sensor head cleaning: In environments with heavy oil fumes or dust, surface contamination can reduce sensitivity. It is recommended to gently wipe with anhydrous ethanol or blow with low-pressure dry air every 3–6 months.

• Circuit inspection: Check terminal oxidation and ensure RS485 bus termination resistors are securely connected.

Frequently Asked Questions (FAQ)

Q: Why does the displayed measurement fluctuate significantly?
A: This is usually caused by installation too close to bends or fans. Turbulence inside the duct results in unstable air velocity. It is recommended to extend the probe toward the centerline of a straight duct section or increase data smoothing time in the software.

Q: Can the device measure high-temperature exhaust gases?
A: Nexisense duct series offers certain high-temperature resistance. However, if the medium temperature exceeds 80°C for extended periods, a high-temperature customized version with cooling or an extended probe is recommended.

Q: What should be done if Modbus address conflicts occur?
A: Nexisense supports both software configuration and physical DIP switch address settings. Even without a computer on-site, the device ID can be quickly modified using DIP switches.

Conclusion

In today’s pursuit of digital transformation, airflow inside ducts is no longer an “uncontrollable” black box. With outstanding hot-film sensing technology, robust industrial structural design, and intelligent data processing solutions, Nexisense duct air velocity transmitters provide solid data support for HVAC, environmental protection, and industrial production.

Choosing precision means choosing safety and energy efficiency. Nexisense is committed to mapping accurate airflow trajectories through every single probe.

If you require detailed selection tables or project-specific technical support, please contact the Nexisense expert team. We provide comprehensive services ranging from hardware installation to system integration.