Ducted wind speed sensor how to measure duct air pressure, air velocity, air volume

When it comes to weather monitoring, wind speed plays a crucial role. To measure wind speed, there are various types of wind speed sensors available. Some of the commonly used wind speed sensors include standard cup wind speed sensors and ultrasonic wind speed sensors. However, there are other types of wind speed sensors such as duct wind speed transmitters that are not as common but are still widely used.

Let's view measuring wind pressure, wind speed, and air volume in ventilation ducts has been carried out using various methods in the past.

I. Measuring position and measuring point

(A) The choice of measurement location

Determination of wind speed and air volume in the ventilation duct is converted by measuring pressure. Measure the real pressure value of the gas in the pipeline, in addition to the correct use of pressure measuring instruments, a reasonable choice of measurement section, and reducing airflow disturbance on the measurement results have a great impact. The measuring section should be selected as far as possible in the gas flow smooth straight pipe section. The measuring section is located in front of the elbow, tee, and other shaped parts (relative to the direction of airflow), the distance from these parts should be more than 2 times the diameter of the pipe. When the measurement section is located behind the above components, the distance from these components should be greater than 4 to 5 times the diameter of the pipe. When the test site it difficult to meet the requirements, to reduce the error may be appropriate to increase the measurement point. However, the minimum distance of the measurement section from the shaped parts is at least 1.5 times the diameter of the pipe.

It should not be used as a measurement cross-section if any of the measurement points contain zero or negative values, indicating that the airflow is not stable. Sections should not be measured as sections if the air flows out of the duct center line by more than 15° (check method: Bitou end of the direction of the airflow, slowly swing Bitou, until the maximum dynamic pressure is reached, then the Bitou and the duct wall of the vertical line of the angle that is the direction of airflow and the center line of the airflow angle deviation). 

(ii) Test holes and measurement points

Due to the non-uniformity of velocity distribution, the pressure distribution is also non-uniform. Therefore, it is necessary to measure at multiple points on the same section and then find the average value of the section.

1 Circular duct

Divide the pipe section into a certain number of equal rings corresponding to the length of the pipe, and place two perpendicular measurement holes in the same section. For circular ducts, the greater the number of measurement points, the greater the measurement accuracy.

2 Rectangular duct

A duct section can be divided into several equal sections, with the measurement point centered in the center of every small rectangle, the length of each rectangle is about 200mm, and the distance between the measurement point and the pipe wall coefficient (based on the pipe diameter) can be calculated.).

II. Determination of pressure in the duct

(A) principle

Measurement of the pressure of the gas in the duct should be carried out in the pipe section of the gas flow is relatively smooth. Tests need to determine the static pressure of the gas, dynamic pressure, and full pressure. Measure the full pressure of the gas orifice should be facing the direction of the airflow in the duct, the orifice of the static pressure should be perpendicular to the direction of the airflow. When measuring full pressure and static pressure with a U-shaped manometer, the other end should be connected to the atmosphere (when using an inclined micromanometer to measure pressure in a positive-pressure tube section, one end of the tube should be connected to the atmosphere, and when measuring pressure in a negative-pressure tube section, the open end of the container should be connected to the atmosphere). Therefore, the pressure read on the manometer is the pressure difference between the gas pressure in the duct and the atmospheric pressure (i.e., the relative pressure of the gas). Atmospheric pressure is generally measured with an atmospheric pressure gauge. As the full pressure is equal to the dynamic pressure and static pressure of the algebraic sum, can be measured only two of the value, the other value is obtained by calculation.

III.Application Scenarios for Duct Wind Speed Sensors

A ducted wind speed sensor is a specialized device designed to measure the velocity of air or wind within a confined space, typically a duct or ventilation system. These sensors are commonly used in various industrial and environmental applications to monitor and control airflow. Here are some common applications for ducted wind speed sensors:

1. HVAC Systems:

   • Ducted wind speed sensors are frequently used in heating, ventilation, and air conditioning (HVAC) systems to ensure proper airflow and ventilation. They help maintain indoor air quality and temperature control.

2. Cleanroom Monitoring:

   • In cleanroom environments like pharmaceutical manufacturing or semiconductor production, precise control of airflow is critical to maintain sterile or controlled conditions. Ducted wind speed sensors help ensure that laminar airflow rates meet specific requirements.

3. Industrial Ventilation:

   • Manufacturing facilities often use ducted wind speed sensors to optimize ventilation and exhaust systems, ensuring that harmful fumes, dust, or contaminants are adequately removed from the workspace.

4. Laboratory Ventilation:

   • Laboratories and research facilities rely on ducted wind speed sensors to maintain safe and controlled conditions for experiments, chemical handling, and safety compliance.

5. Commercial Buildings:

   • In large commercial buildings, ducted wind speed sensors help maintain comfort and energy efficiency by adjusting HVAC systems based on real-time airflow measurements.

6. Data Centers:

   • Data centers require precise temperature and airflow control to prevent equipment overheating. Ducted wind speed sensors assist in optimizing cooling systems for energy efficiency and equipment performance.

7. Environmental Monitoring:

   • Ducted wind speed sensors can be used in environmental monitoring applications to measure airflow in ducts that transport gases, monitor ventilation in tunnels, or evaluate wind flow in wind tunnels for research purposes.

8. Energy Efficiency:

   • In energy management systems, ducted wind speed sensors help reduce energy consumption by ensuring that ventilation systems only operate when necessary and at the right capacity.

9. Safety Compliance:

   • Some industries, like chemical processing or mining, use ducted wind speed sensors to ensure compliance with safety regulations by monitoring and controlling potentially hazardous gas or dust concentrations in ducts.

10. Research and Development:

    • Ducted wind speed sensors are essential tools in research and development for studying fluid dynamics, aerodynamics, and airflow patterns in various applications.

These are just a few examples of the many applications for ducted wind speed sensors. The specific use case will determine the sensor's design, features, and calibration requirements to ensure accurate and reliable measurements in the given environment.