Pitot Tubes

Applications in HVAC

Heating, ventilation, air-conditioning and refrigeration professionals are among the world’s foremost experts in airflow: balancing pressures, measuring velocities, ensuring that systems operate at maximum efficiency. So these pros know all about their trusty Pitot tube, the simple yet brilliant device that measures air velocity and calculates its flow rate.

Pitot tubes are widely used in HVAC systems for the following purposes:

 

• • Airflow Measurement: They provide accurate measurements of air velocity in ducts, which is essential for balancing and optimising HVAC systems.

• • Flow Rate Calculation: By knowing the velocity and the cross-sectional area of the duct, the volumetric flow rate can be calculated using the formula:

Q=V×AQ=V×A

Where Q is the flow rate, V is the velocity, and A is the cross-sectional area of the duct.

Advantages

 

• • Accuracy: Pitot tubes are considered the standard for measuring airflow in HVAC applications due to their reliability and accuracy.
    This is especially true in mid to high-velocity airflow scenarios.

• • Simplicity: They are relatively simple devices that can be used across a range of environmental conditions.
    For example, they can be used in high temperatures and pressures.

• • Summary: Pitot tubes are essential tools in HVAC for measuring airflow and ensuring efficient system performance.
    They provide critical data on air velocity and flow rates.

 

A Pitot tube arrangement typically consists of two tubes, one before and one after the fan, to measure the pressure difference.

This tube senses the differential pressure in the duct.

A typical AHU will have pitot tubes fitted across the supply fan, the extract fan, the supply panel filter, the extract panel filter, and the supply bag filter. This setup allows for monitoring fan flows and dirty filters.

The device to monitor the differential pressure can be found at https://hvacproducts.co.uk/product/air-differential-pressure-switch-with-duct-kit/

Pitot tubes, in their elegant simplicity, serve as a testament to the blend of science and engineering. From the skies above to the air handling units below, they play a pivotal role in ensuring safety, enhancing knowledge, and promoting innovation. 

By understanding the mechanics of pitot tube pressure, we not only gain a glimpse into the world of fluid dynamics but also appreciate the myriad ways this tool shapes industries and practices. 

As technology continues to evolve, one can only imagine the new frontiers that the pitot tube will touch, further solidifying its position as a cornerstone in the realm of measurement and analysis.

For the history of the Pitot Tube, please check out this page at https://pitottube.co.uk/history/