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Daviteq Air / Gas Flow Measurement Technologies
Daviteq AFD Air/Gas Flow Sensor is the flow probe that utilizes the Pitot tube measurement principle. This flow sensor
is intended to use in the Duct Air of the HVAC system to measure the Air velocity and thus calculate the Air flow. The
probe has various sizes to suit the pipe/duct size from 80mm to 2000mm in diameter.
In the 18th century, French engineer Henri Pitot invented the Pitot tube, and in the mid-19th century, French scientist
Henry Darcy modified it to its modern form. In the early 20th century, German aerodynamicist Ludwig Prandtl
combined the static pressure measurement and Pitot tube into the Pitot-static tube, which is widely used today.
A schematic of a Pitot-static tube is shown in Figure 1. There are 2 openings in the tubes: one opening faces the flow
directly to sense the stagnation pressure, and the other is perpendicular to the flow to measure the static pressure.
Figure 1. Schematic of a Pitot-static tube
The pressure differential is required to determine the flow speed, typically measured by pressure transducers. The
below formula calculates the fluid velocity:
V = K x SQRT (DP)
Where:
- DP: Differential pressure measured by the sensor
- K: is the factor of the sensor design and the fluid type.
AFD flow sensor specification
Sensor technology Pitot tube flow sensor
Compatible gases Air, Nitrogen, CO2, Oxygen.
Differential pressure range +/- 2 in-H2O
Fluid velocity range 0 - 28.5 m/s with Air at 25 oC
Max allowable static pressure 270 in-H2O
Burst static pressure 2800 in-H2O
Max allowable fluid velocity 45 m/s (Air) at 25 oC
Drift +/- 0.35m/s in 12 months (Air)
Daviteq AFD Air/Gas Flow Sensor
1. Overview
2. Detail measurement principle and its
specification