Airflow Meters & Anemometers
An airflow meter (anemometer) is a handheld instrument that measures the speed of moving air — air velocity — and, in models with a CFM/CMM mode, converts that velocity into a volume of air moving past a point over time. Air velocity is read directly in metres per second, feet per minute, km/h, mph or knots; airflow volume is calculated as velocity multiplied by the cross-sectional area of the duct, grille or opening being tested, and is expressed in CFM (cubic feet per minute) or CMM (cubic metres per minute).
Ecotao supplies the Extech range of airflow meters and anemometers, from pocket-sized vane models to heavy-duty metal vane and hot-wire instruments with SD card datalogging, used across HVAC commissioning, industrial ventilation auditing, mining and confined-space ventilation checks, greenhouse and poultry-house climate control, and general facilities maintenance in South Africa.
How to choose an airflow meter
The right instrument depends on where the sensor needs to reach, what the airflow is doing to the environment (heat, moisture, corrosive gas), and whether the reading needs to be logged over time. Work through these four questions before selecting a model:
1. Open duct or grille, or a tight opening?
A rotating vane wheel (407113, AN100, SDL300) needs open space to spin freely and suits grilles, open ducts and outdoor readings. A hot-wire probe (407119, 407123) is thin and telescopic, so it reaches into narrow ducts, register slots and confined vents a vane cannot enter.
2. Do you need airflow volume, or just velocity?
If the task is sizing a fan, checking extraction rates, or verifying compliance with a ventilation requirement, you need a CFM/CMM-capable model (407113, 407119, AN100) that stores the duct area and calculates volume automatically. If you only need to confirm air is moving at a point, a velocity-only reading (45118, 407123) is enough.
3. What temperatures will the sensor see?
Standard hot-wire and mini vane sensors are rated to around 50°C. Where ductwork or process air runs hotter — furnace exhausts, drying ovens, hot process lines — the metal vane models (407113, SDL300) are rated to 70–80°C and the SDL300 additionally accepts a Type K/J thermocouple probe for direct high-temperature contact readings.
4. Single spot-check, or an unattended monitoring run?
For a quick site walk-through, any handheld model with Min/Max and Data Hold is sufficient. For a commissioning report, an energy audit, or an unattended multi-hour monitoring run, the SDL300's SD card datalogger timestamps and stores readings in Excel-compatible format for later analysis on a PC.
Airflow meters & anemometers
Extech 407113
Heavy Duty CFM Metal Vane AnemometerA rugged metal vane anemometer built for open-duct and grille work where sensors take a beating. The metal vane withstands air temperatures up to 80°C, so it holds up in warehouse ventilation checks, industrial extraction audits and outdoor site work where a plastic vane wouldn't survive.
- Air velocity40–3346 ft/min (0.2–17.0 m/s)
- Air volumeCFM & CMM, area-based
- Max sensor temp80°C (175°F)
- Power4 × AA batteries
Extech 407119
Heavy Duty CFM Hot Wire Thermo-AnemometerA hot-wire thermo-anemometer whose telescoping probe extends up to 3ft (940mm), reaching into HVAC ducts and ventilating systems that a vane wheel can't access. It displays air flow (CFM/CMM), air velocity and temperature at once, with a 20-point averaging mode for stable duct-traverse readings.
- Air velocity40–3346 ft/min (0.2–17.0 m/s)
- Probe reachTelescopes to 3ft (940mm)
- Air volumeCFM & CMM simultaneous
- Power4 × AA batteries
Extech 407123
Heavy Duty Hot Wire Thermo-AnemometerBuilt for the smallest openings: the telescoping probe fits into narrow HVAC ducts and other small vents that even the 407119 can't reach. Air velocity and temperature display simultaneously on a large dual LCD, with Min/Max and Data Hold for one-handed spot-checks.
- MeasuresAir velocity + temperature
- Probe reachTelescoping, small-opening design
- DisplayDual LCD, 1.4in (36mm)
- Power6 × AA batteries
Extech 45118
Mini Thermo-AnemometerA waterproof, pocket-sized anemometer for quick air velocity, temperature and windchill checks. The fold-up impeller housing extends to 229mm for better reach and folds flat for storage; it's tripod-mountable for hands-free outdoor readings.
- Air velocity216–3936 ft/min (1.1–20 m/s)
- Accuracy±(3% rdg + 40 ft/min)
- Weight95g (3oz)
- PowerCR2032 lithium battery
Extech AN100
CFM/CMM Mini Thermo-AnemometerA low-friction 72mm ball-bearing vane wheel on a 120cm cable, so the sensor can be positioned in a duct or grille while the display stays in hand. Duct area is stored in memory between power cycles, so repeat CFM/CMM readings on the same duct don't need re-entering.
- MeasuresAir flow, velocity & temperature
- Accuracy±3% of velocity reading
- Averaging20-point for Air Flow
- Power9V battery
Extech SDL300
Metal Vane Thermo-Anemometer/DataloggerThe metal vane withstands 70°C and up to 6900ft/min, and every reading is timestamped and written to an SD card in Excel-compatible format — ideal for unattended commissioning runs and energy audits where a written record is required. A Type K/J thermocouple input adds direct-contact high-temperature measurement.
- DataloggingSD card, Excel format, 1–3600s rate
- Storage99 manual + 20M logged (2G card)
- Max sensor temp70°C (158°F)
- Power6 × AA batteries
Compare Extech airflow meters & anemometers
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| Model | Sensor type | Velocity range | CFM/CMM airflow | Max sensor temp | Datalogging | Best for |
|---|---|---|---|---|---|---|
| 407113 | Metal vane | 40–3346 ft/min | Yes | 80°C | No | Open ducts & grilles, hot environments |
| 407119 | Hot wire, telescoping | 40–3346 ft/min | Yes | 50°C | No | HVAC duct traverses, narrow vents |
| 407123 | Hot wire, telescoping | Velocity + temp only | No | 50°C | No | Very small openings, quick spot-checks |
| 45118 | Mini vane, pocket | 216–3936 ft/min | No | 50°C | No | Outdoor readings, field walkthroughs |
| AN100 | Vane wheel on cable | Velocity + CFM/CMM | Yes | 50°C | No | Repeat CFM checks on the same duct |
| SDL300 | Metal vane + thermocouple input | Up to 6900 ft/min | No (velocity + temp) | 70°C (probe higher via TC) | Yes — SD card, Excel format | Commissioning reports, unattended logging |
Frequently asked questions
What is the difference between an anemometer and an airflow (CFM) meter?
An anemometer measures air velocity — the speed of moving air — in units like m/s or ft/min. An airflow meter converts that velocity into a volume of air per unit time, expressed as CFM or CMM, by multiplying velocity by the duct's cross-sectional area. Most models on this page do both: they read velocity directly and calculate CFM/CMM once the duct area is entered.
How do I convert air velocity to CFM airflow?
CFM = air velocity (ft/min) × duct cross-sectional area (ft²). Measure the duct's height and width in inches, divide by 144 to get square feet, then multiply by the velocity reading. Models with a built-in CFM/CMM mode, such as the 407113, 407119 and AN100, store the area value and run this calculation automatically.
What is the difference between a vane anemometer and a hot-wire anemometer?
A vane anemometer uses a small rotating impeller and calculates air speed from how fast it spins — robust and well suited to open ducts and grilles. A hot-wire anemometer uses a heated sensor element and reads air speed from the cooling effect of the airflow, allowing a thin telescoping probe to reach into narrow ducts and confined spaces a vane wheel can't enter.
Which airflow meter suits HVAC duct testing and commissioning in South Africa?
For standard duct traverses and grille testing, a hot-wire model with a telescoping probe such as the 407119 or 407123 reaches ducts a vane wheel cannot. For commissioning reports that need a documented record, the SDL300 logs velocity and temperature directly to an SD card in Excel format.
Do any of these airflow meters have data logging?
Yes — the SDL300 timestamps and stores air velocity and temperature readings to an SD card in Excel-compatible format, with an adjustable sampling interval from 1 to 3600 seconds, suited to long unattended monitoring runs.
What ventilation standards apply to workplace air movement in South Africa?
Regulation 5 of the Environmental Regulations for Workplaces, made under the Occupational Health and Safety Act 85 of 1993, requires every workplace to be ventilated — naturally or mechanically — so the air employees breathe is safe, carbon dioxide stays within set limits, and any explosive or flammable gas concentration stays below its lower explosive limit. Confirming compliance in practice means measuring actual air movement and airflow volume in the space, which is the role a handheld anemometer or airflow meter plays on site.
Need help choosing the right airflow meter?
Tell us the duct size, opening, temperature range or logging requirement and we'll recommend the right Extech model for the job.
Ecotao (Cape Town, South Africa) supplies Extech Instruments test & measurement equipment. For technical advice or a formal quotation, contact the head office on +27 21 911 5835, Zak on 086 142 8716, Zaid on 082 390 3989, or email sales@ecotao.co.za.