Quick Answer
Anemometer calibration uses a NABL-calibrated wind tunnel or laminar flow reference section to generate known air velocities. The anemometer under test is placed in the uniform flow field and its readings are compared with the reference air velocity at 5–8 calibration points covering its measurement range.
Key Takeaways
- Anemometer calibration range at Prism: 0.1 m/s to 30 m/s (vane and hot-wire types).
- Reference standard: NABL-calibrated laminar flow wind tunnel or pitot tube + reference manometer.
- Calibration per ISO 16620 and EN 12599 for cleanroom and HVAC airflow verification.
- Hot wire anemometers are most sensitive to temperature — calibration includes temperature correction.
- NABL certificate includes velocity accuracy and expanded uncertainty at each calibration point.
Anemometer Types Calibrated at Prism
Vane Anemometer
Rotating impeller type. Range: 0.3–30 m/s. Used for HVAC duct velocity, cleanroom face velocity.
Hot Wire Anemometer
Thermal mass type. Range: 0.1–20 m/s. High sensitivity at low velocities — cleanrooms, fume hoods.
Ultrasonic Anemometer
Transit time type. Range: 0–60 m/s. Used outdoors for wind monitoring (meteorology, wind farms).
Pitot Tube Anemometer
Differential pressure type. Range: 1–50 m/s. Used for duct flow, stack velocity (GPCB compliance).
Anemometer Calibration for Cleanroom Air Supply
ISO 14644-3 requires airflow velocity measurement at HEPA filter faces for cleanroom commissioning and requalification. Typical face velocity for Grade A (ISO Class 5) unidirectional flow cleanrooms is 0.36–0.54 m/s. Hot-wire and vane anemometers must be NABL-calibrated in this low-velocity range (0.1–0.6 m/s) for accurate cleanroom airflow verification.
Frequently Asked Questions
Can Prism calibrate anemometers at very low velocities (0.1 m/s) for cleanrooms?
Yes. Prism calibrates hot-wire anemometers down to 0.1 m/s for cleanroom face velocity measurement, using a precision laminar flow generator with NABL-calibrated reference Pitot tube.
How often should anemometers be calibrated?
Annual calibration is standard. Cleanroom anemometers used for ISO 14644 requalification and HVAC commissioning should be calibrated every 12 months or before each major requalification.
Does Prism calibrate weather station anemometers?
Yes. Prism calibrates cup anemometers and ultrasonic wind sensors used in weather stations and wind farm monitoring, in the range 0.5–30 m/s.
Is anemometer calibration required for GPCB stack emission monitoring?
Yes. Stack velocity measurement (using Pitot tube + differential pressure manometer) for GPCB OCEMS stack monitoring requires calibrated anemometry instruments per USEPA Method 2 and CPCB guidelines.
What is the expanded uncertainty for anemometer calibration at Prism?
Prism achieves expanded uncertainty of ±2–3% of reading (k=2) for vane anemometers and ±3–5% for hot-wire anemometers in the 0.1–30 m/s range.
Written by
Er. Parthiv Kinariwala
Managing Director · Prism Calibration Centre · NABL CC-2480 · Ahmedabad
Er. Parthiv Kinariwala founded Prism Calibration Centre in 2004 and has over 20 years of hands-on experience in calibration engineering, NABL accreditation, and industrial compliance. His team performs 10,000+ calibrations annually from the Vatva GIDC laboratory, serving 5000+ industries across Gujarat.
Prism Calibration Centre — Vatva GIDC, Ahmedabad
Prism Calibration Centre
F-101, Rudraksh Complex 2, Phase 3, GIDC Vatva, Near Jasoda Nagar Cross Road, Ahmedabad — 382445, Gujarat, India
Phone: +91 98245 26444
Email: info@prismcalibration.com
NABL: CC-2480 · ISO/IEC 17025:2017
Hours: Mon–Sat, 9:00 AM – 7:00 PM