Balometer Flow Hoods
Direct Supply and Exhaust Airflow Measurement for HVAC Systems
Balometer Flow Hoods are professional HVAC measuring instruments used to directly measure the total airflow passing through grilles, anemostats, diffusers, linear slots and other air terminal devices.
The sealed measurement hood encloses the complete air terminal and directs airflow to the instrument’s measuring base. Supply or exhaust airflow is determined through multi-point differential pressure measurement. Suitable models can also provide air temperature, pressure, averaging and data logging functions.
40–3,500 m³/h
Provides a wide airflow measurement range for different grille and diffuser applications.
Supply and Exhaust Measurement
On suitable models, airflow direction can be detected automatically to identify supply or exhaust flow.
48-Point Measurement
Multiple points distributed across the measuring base help average the airflow profile.
Interchangeable Hoods
Hood options can be used to suit different grille, anemostat and diffuser dimensions.
What Are Balometer Flow Hoods?
A balometer is a portable HVAC test instrument that measures total airflow through a flow hood enclosing an air terminal outlet or return surface. Rather than taking multiple anemometer readings across the grille surface, it determines the total airflow passing through the terminal in a single measurement.
Air inside the measurement hood is directed to the multi-point flow field in the instrument base. The pressure difference detected by the differential pressure sensor is converted into volumetric airflow using calibration data.
Balometers support fast and repeatable measurements during HVAC commissioning, air balancing, periodic maintenance, cleanroom validation and grille performance checks.
How Do Balometer Flow Hoods Work?
The Terminal Is Enclosed
A correctly sized hood is positioned to enclose the complete grille or diffuser.
Air Is Captured
Supply or return air is directed through the sealed hood to the measuring base.
Differential Pressure Is Measured
An electronic sensor detects the differential pressure generated across the multi-point flow field.
Airflow Is Displayed
The measured pressure difference is corrected for temperature and atmospheric conditions, then converted into airflow.
Balometer Flow Hood Measurement Functions
Total airflow through the terminal can be displayed in m³/h, l/s or other units depending on the model.
Air temperature can be monitored simultaneously using the temperature sensor in the measuring base.
Suitable instruments can automatically determine whether air is moving in the supply or exhaust direction.
Automatic or point-by-point averaging provides representative results where airflow varies.
The measured value can be held on the display, making results easier to read at difficult-to-access points.
Measurement data can be transferred to a computer through USB or a suitable communication connection.
Balometer Flow Hood Technical Specifications
| Technical Parameter | Reference Value | Description |
|---|---|---|
| Airflow measurement range | 40–3,500 m³/h | The measuring range may vary according to the product model and hood construction. |
| Airflow accuracy | ±3% of reading ±10 m³/h | Reference value under laboratory and required compensation conditions. |
| Airflow resolution | 1 m³/h | The smallest airflow increment that can be displayed. |
| Temperature measurement range | 0°C to 50°C | Reference range for the temperature sensor in the measuring base. |
| Temperature accuracy | ±2% of reading ±0.1°C | May vary according to ambient and operating conditions. |
| Pressure measurement range | -2,500 to +2,500 Pa | Applicable to models with a removable micromanometer unit. |
| Pressure accuracy | ±0.2% of reading ±2 Pa | Can be used for differential pressure and filter monitoring applications. |
| Measurement grid | 48-point flow field | Helps average the airflow profile across the hood section. |
| Protection class | IP54 | Protection level of the measuring unit against dust and water splashes. |
| Operating temperature | 0°C to +60°C | Reference ambient temperature range specified for instrument use. |
| Reference weight | Approximately 3.6 kg | May vary according to hood and instrument configuration. |
| Calibration | Supplied with calibration certificate | Periodic calibration is recommended to maintain measurement traceability. |
Technical values are reference measuring instrument data. Before final product selection, the manufacturer’s current datasheet, calibration scope and measurement uncertainty should be verified.
Flow Hood Size Options
| Hood Size | Configuration | Example Application |
|---|---|---|
| 610 × 610 mm | Standard | Standard square ceiling diffusers and anemostats. |
| 720 × 720 mm | Optional | Larger square ceiling terminals. |
| 1,020 × 1,020 mm | Optional | Large square grilles and diffusers. |
| 720 × 1,320 mm | Optional | Rectangular air terminal devices. |
| 420 × 1,520 mm | Optional | Long and narrow linear grille applications. |
The hood size should completely enclose the air terminal and form the closest possible seal against the ceiling surface.
Removable Micromanometer Function
Models with a removable measuring unit can be used as differential pressure instruments independently from the flow hood. This allows different HVAC tests to be carried out with a single measurement system.
A Pitot tube can be used to measure dynamic pressure and air velocity in an air duct.
Differential pressure before and after a filter can be measured with two pressure hoses to monitor its contamination level.
HVAC system performance can be evaluated through static, dynamic or total pressure measurements.
Airflow Measurement Steps with a Balometer
A suitable hood size that completely encloses the air terminal to be measured is selected.
The hood support rods, measuring base and electronic measuring unit are assembled correctly.
The hood is placed around the grille with no gaps and centred over the air terminal.
The instrument is held steady until the airflow value shown on the display becomes stable.
Airflow, temperature, airflow direction and terminal information are recorded.
The measured value is compared with the design airflow, then the damper or terminal is adjusted if required.
Applications of Balometer Flow Hoods
Advantages of Balometer Flow Hoods
Balometer Flow Hood Selection Criteria
Measurement and Application Note
Positioning a flow hood over an air terminal can affect terminal discharge pressure and airflow to a certain extent. The back-pressure effect of the instrument should be assessed for low-pressure terminals or terminals with sensitive airflow characteristics.
A gap between the hood and the ceiling or wall can allow air to enter or leave outside the measuring area. During measurement, the hood frame should sit evenly and as airtight as possible against the surface.
For field methods used to determine airflow at air control ports, including diffusers and supply or exhaust openings, see ISO 16956:2015.
Measurement accuracy depends on instrument calibration, air terminal geometry, airflow turbulence, hood position, filter condition, air temperature and the measurement method applied by the user.
Get Technical Support for Balometer Flow Hood Selection
Balometer selection should be based on the airflow range, terminal dimensions, supply or exhaust direction, measurement accuracy and reporting requirements.
You can receive technical information about suitable balometers, flow hoods and measurement accessories for HVAC air balancing, grille airflow measurement, cleanroom validation, testing and commissioning applications.
