Measuring the wind speed in front of the kitchen hood (Kitchen Hood Face Velocity)

Measuring the wind speed in front of the kitchen hood (Kitchen Hood Face Velocity)

The main objective is to confirm that the Hood can capture & contain smoke, oil vapor.

and heat efficiently It does not measure only the air volume (CFM or L/s) alone.

Generally used in conjunction with a smoke test (Smoke Test) to confirm actual absorption. 


Equipment used
* Hot Wire Anemometer (most recommended)
* Vane Anemometer
* Smoke Tube or Smoke Generator for testing smoke absorption

Measuring steps
1. Turn on the system to work normally.
* Turn on the exhaust fan.
* Turn on the Makeup Air system according to actual use condition.
* If possible, turn on the cooking equipment to create a Thermal Plume.

2. Divide the area in front of the Hood into Grid.
* Divide the measuring squares into similar sizes, such as 300 × 300 mm or approximately 1 ft² per point.
* A large hood should be measured at several points (9–25 points).

3. Measured at the center of each square.
* Hold the probe perpendicular to the wind direction.
* The probe plane is located in front of the Hood.
* Record wind speed value (m/s)

The method of dividing a grid and measuring values at the center of each grid is the most widely used method for measuring hood face velocity. 

4. Calculate the average.
V_{avg}=\frac{V_1+V_2+\cdots+V_n}{n}
Example
Point speed (m/s)
1 0.46
2 0.50
3 0.44
4 0.48
5 0.47
6 0.49
7 0.45
8 0.46
9 0.50
averageV_{avg}=0.47\ \text{m/s}

Interpretation of results
For commercial kitchen hoods Face Velocity is not fixed like a laboratory fume hood.

But by field work experience If the speed in front of the Hood is approximately 0.25–0.50 m/s and

Passed the smoke test and can capture well. The efficiency depends on the Hood type, overhang,

Exhaust air volume and makeup air system arrangement as well 

Additional things to check
* ✅ Smoke Test must not have smoke leaking out the front.
* ✅ No wind from the air conditioner or door blowing in front of the hood.
* ✅ Makeup Air is not so strong that it pushes smoke out of the Hood.
* ✅ Check the exhaust air volume (CFM or L/s) to match the design.


For TAB (Testing, Adjusting & Balancing) work, I can prepare speed measurement form

Kitchen Hood page with a table for recording 25 points and calculating the average automatically in Excel.

Summary of the steps for measuring Face Velocity in front of the Hood.