Anemometer: Advanced Technology for Precise Air Velocity Measurement

Hot Wire Anemometer: Advanced Technology for Precise Air Velocity Measurement

Have you ever wondered how to accurately measure air speed, especially in HVAC systems or industrial environments? The answer lies in the hot wire anemometer – a groundbreaking technology that has revolutionized how we monitor and control airflow.

The History and Working Principle Behind the "Hot Wire"

This pioneering device was developed in 1914 by Louis Vesso King. He not only created the first hot wire anemometer but also laid the foundation for King's Law. This law quantitatively describes heat transfer in moving air streams using a heated electrical conductor.

When air passes over the heated wire, it causes a loss of heat from the wire, resulting in a temperature change. This precise temperature change is the key to determining air velocity.

How Hot Wire Anemometers Work in Practice

A typical hot wire anemometer is configured with two distinct sensors:

• Temperature Compensation Sensor: This sensor measures the actual air temperature within the duct or environment. This is crucial for accuracy, as changes in ambient temperature can affect measurement results.

• Velocity Sensor: This sensor is heated to a constant temperature above the ambient air temperature. As air flows past it, it cools the velocity sensor. The system continuously adjusts the power supplied to maintain the sensor's stable temperature.

The difference in power required to keep the velocity sensor at a constant temperature, compared to a no-flow state, can be inversely referenced back to a specific air velocity value. This process is commonly achieved using a Wheatstone bridge circuit – a well-known electrical circuit prized for its extreme precision in resistance measurement.

Introducing the Air Velocity Transmitter, Series AVUL

With technological advancements, hot wire anemometers have continuously improved. The Air Velocity Transmitter, Series AVUL and AVLV, product lines are clear examples of this progress. These are prime illustrations of hot wire anemometers enhanced with superior features, delivering outstanding performance and maximum convenience:

• BACnet and Modbus® Communication: This allows these sensors to be daisy-chained and seamlessly integrated into Building Management Systems (BMS) or industrial automation systems. This provides remote data access, efficient monitoring, and optimized operation.

• Specialized Conformal Coating: This protects the sensors from harsh environmental elements, ensuring durability and reliability even in damp, dusty, or chemical-laden conditions.

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