Anemometers and Air Flow Meters for Accurate Measurements

OSI's optical flow meters achieve ±2% accuracy across their full measurement ranges, from as low as 0.03 m/sec to as high as 170 m/sec for flare stacks, or 0–100 m/sec for general industrial stacks. This accuracy is maintained without field calibration, is unaffected by temperature, pressure, gas density, moisture, or opacity changes, and is validated by a NIST-certified measurement algorithm supported by over 20 million hours of observation data.

The three primary anemometer types are: (1) Cup anemometers, which use rotating cups to measure wind speed mechanically; (2) Ultrasonic anemometers, which use sound wave transit times between transducers to calculate velocity; and (3) Optical anemometers, such as OSI's LOA and OFS series, which use optical scintillation to measure path-averaged crosswind velocity and turbulence with no moving parts and no field calibration required.

Optical scintillation refers to the rapid fluctuation of light intensity caused by air turbulence and temperature gradients along an optical beam path. OSI's sensors transmit an infrared beam across a duct, stack, or open atmosphere. A DSP-based receiver analyzes the scintillation pattern to compute velocity and turbulence parameters. This patented technique is NIST-certified and immune to pressure, moisture, and gas composition variables.

No. OSI's optical flow sensors are factory pre-calibrated and use a drift-free measurement algorithm — they never require field calibration. Built-in automatic calibration checks and continuous self-test diagnostics operate 24/7/365. The LOA series requires only a semi-annual preventative maintenance inspection for window cleaning and optical alignment verification, not recalibration.

Yes. The OFS-2000 series and OFS-2000F are certified for EPA 40 CFR Part 75 compliance for stack gas flow monitoring at power plants and industrial facilities. The LOA-105 holds EPA Method 14 equivalency approval for airflow measurement in aluminum smelter roof vents. All applicable products use a NIST-certified algorithm and support mass emissions reporting requirements.

OSI's anemometers and flow meters serve power plants, oil refineries, chemical plants, aluminum smelters, airports, environmental monitoring agencies, and research institutions. They operate reliably in extreme conditions including high temperatures, high dust and particulate concentrations, high opacity, high moisture, entrained liquid droplets, and corrosive HF gas environments found in aluminum smelter pot rooms.