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Arduino Air Flow Meter: DIY Pulse Output Hot-Wire Ventilation Projects
Quick Answer: A DIY Arduino hot-wire air flow meter works for low-cost ventilation tests and pulse counting in ducts from DN100 to DN300. It uses a heated sensor, an amplifier, and a square wave pulse output from the Arduino board. For industrial air, gas, or compressed air measurement, Silver Automation Instruments supplies thermal mass flow meters with 4-20 mA HART, pulse output, and RS485 Modbus.
What You Need for a Basic Build
Use an Arduino Uno or Nano, a hot-wire sensor, an instrumentation amplifier, and a 24 V DC supply. The hot-wire element is often a thin platinum wire or a PT100 heated above ambient temperature. Airflow cools the wire. The circuit keeps the wire at a constant temperature or measures the resistance change. Most engineers skip constant current mode because drift is harder to correct.
You also need a 0 to 5 V analog input channel, a pulse output pin, and a small OLED display. Add a 10 k pull-up resistor on the pulse output line. Read the analog voltage every 100 ms and convert it to air velocity with a calibration curve. Test the setup in a straight duct section of DN100 or DN150.
How the Pulse Output Works
The Arduino generates a square wave on digital pin D2. One pulse can equal 0.01 m3 or 0.1 m3 of air. Use an interrupt routine to count pulses for total flow. You can send the pulse signal to a PLC digital input. In practice, pulse output from a DIY board drifts with ambient temperature and dust. You will recheck the zero point more often than expected.
Where DIY Hot-Wire Ventilation Projects Fall Short
Hot-wire sensors are not linear and need frequent calibration. They do not meet ATEX Zone 1, IP67, or high pressure gas line requirements. A ventilation contractor in Vietnam asked us last year about a DN200 dryer exhaust duct. The DIY sensor failed after two weeks because of dust and high humidity. For short lab tests it worked. For process gas or billing it did not.
Here is the thing. A DIY air flow meter measures velocity at one point. You must assume a velocity profile. If the profile changes after a bend, the reading can shift by 10 to 20 percent. An industrial thermal mass flow meter handles this better with probe depth settings and stable calibration.
From Arduino Prototype to Industrial Thermal Mass Flow Meter
Silver Automation Instruments builds inline and insertion thermal mass flow meters for air and gas pipelines from DN15 to DN300. The probe uses two PT100 sensors. One sensor measures gas temperature. The other sensor i
These meters suit air, nitrogen, oxygen, biogas, and flue gas. For a DN50 compressed air line at 8 bar, choose an inline meter with 4-20 mA HART and pulse output. For a large ventilation duct above DN300, choose an insertion type. Media temperature can reach 200 °C. Pressure can reach 4 MPa for inline designs.
Recommended Flow Meters for Related Processes
For compressed air or nitrogen, choose a thermal mass flow meter. For water, wastewater, or chemical dosing, use an electromagnetic flow meter. For diesel, oil, or fuel batching, see our oval gear flow meter for diesel. For high accuracy liquid or gas batching, a Coriolis mass flow meter is the right fit. Silver Instruments also supplies pressure transmitters and paperless recorders for panel monitoring.
FAQ
Question 1: Can a DIY Arduino hot-wire flow meter measure gas mass flow directly?
No. It measures velocity at one point. You must calculate volume flow using the duct area and profile. An industrial thermal mass flow meter measures mass flow directly and compensates for gas temperature.
Question 2: What is the typical price of an industrial thermal mass flow meter?
Basic inline air meters start around a few hundred USD depending on DN size and outputs. A DN25 inline meter with pulse output and 4-20 mA costs less over time than repeated calibration of a DIY sensor on a production line.
Question 3: Which output should I choose for ventilation control?
Use 4-20 mA for analog flow rate and pulse output for total flow. Modbus RS485 is better for multi-drop systems or energy management dashboards.
Question 4: Can you supply a meter for humid or dusty air?
Yes. Ask for a probe with IP65 protection or ATEX Zone 1 depending on the site. Mention dust load, dew point, and duct size when you send the inquiry.
Question 5: Do you supply to Southeast Asia, Oceania, Latin America, Africa, and the Middle East?
Yes. Silver Automation Instruments ships to those regions. We quote in USD, EUR, or local currency depending on the order size and country.
Quote Request and Contact Details
Send us your gas type, flow range in kg/h or m3/h, pipe size DN, temperature in °C, and pressure in bar. We will reply with a model selection and price. Tel: +86-135-1213-1526. Whatsapp: 86-135-12131526. WeChat: +86 13512131526.
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