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Ultrasonic Anemometer Calibrations

Ultrasonic Anemometer Calibrations

Quick Overview

Omni Instruments can provide a calibration certificates for our ultrasonic anemometers, WindSonic, WindObserver and WindMaster anemometers. Calibration are done in a wind tunnel and units can be fixed with a varied wind speed, or rotated with fixed wind speeds. Calibration work is undertaken using wind tunnels traceable to national standards (UKAS) and calibration procedures meet or exceed the requirements of:
ISO16622:2002 Meteorology - Sonic anemometers/thermometers - Acceptance test methods for mean wind speeds.
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Details

Ultrasonic Anemometers are calibrated using the Department of Aeronautics and Astronautics wind tunnel at Southampton University.

This wind tunnel is of the closed circuit type with a single return duct according to the Prandtl scheme. The tunnel provides both high and low speed working sections. Ultrasonic Anemometers are calibrated in the high-speed section, which measures 2.1m x 1.5m x 4.4m (7ft x 5ft 14.5ft).

A 175KW dc motor driving a 6 bladed fan 2.7m in diameter provides the power.

Wind speed is computer controlled by University staff from a dedicated control room. All instruments used in determining wind speed are calibrated and traceable to national UKAS standards.

Calibration Procedure

The Anemometer under calibration is held on a custom-made fixture attached to the base of the wind tunnel so that the Anemometer head protrudes into the air stream. The Anemometer is aligned using a laser with the North arm pointing at a 0° reference mark located within the tunnel.

Ultrasonic Calibration Win Jig Test Software is used to control the complete system calibration process including the rotation of the Anemometer.

The Wind tunnel air speed is set to 12m/s and an un-calibrated run is performed on the Anemometer by rotating it through 360 degrees in 2 degree steps (1 degree for research Anemometers). The readings measured by the Anemometer are stored by Win Jig.

Win Jig then creates a calibration table unique to that Anemometer. This information is uploaded and stored in the Anemometers memory. Then, with the Wind tunnel air speed still set at 12m/s,  the Anemometer is once again rotated through 360 degrees for a calibration check run with the measured values of the Anemometer stored and checked by Win Jig.

Calibration Results

Win Jig uses the calibration check run data to generate a graphical representation of the Anemometers 360 degree response at 12m/s.

The maximum allowable error is ± 1% rms at 12 m/s

Wind Tunnel results are retained on file for future reference.

Please note: Recalibrations will require an additional charge for a full test and any necessary repairs to return units to original specifications prior to calibration. 

Availability: Stock Item

 

Components / Downloads

For further information, technical advice, or a quotation please call or email us. If you are not sure which product you need one of our technical sales advisors will be happy to discuss your application. We also accept company purchase orders by fax or post. Credit card orders can also be placed over the phone for any product.

REF DESCRIPTION DOWNLOADS PRICE ORDER ITEM
CAL2AXISFIXEDPOINT
Calibration 2 Axis - Fixed Point (Wind Tunnel). The calibration procedure involves the unit being fixed in one point facing North with a varying wind speed from 0 to 30 or 40m/s. The calibration certificate then compares the wind tunnel velocity readings to those collected by the unit.
View FileDatasheet
   Size: (163.52 KB)
£216.34
or call us for a quote
CAL2AXISROTATE
Calibration 2 Axis - Rotate (Wind Tunnel). The calibration procedure involves a fixed wind velocity and the unit is rotated from 0 to 360 Degrees in 180 separate steps, providing a reading every 2 Degrees. The calibration certificate then compares the fixed wind velocity of the wind tunnel to the readings collected by the unit at each step as a percentage error.
£416.62
or call us for a quote
 
3-Axis Calibration
CAL3AXISROTATE
Calibration 3 Axis - Rotate (Wind Tunnel). The calibration procedure involves a fixed wind velocity and the unit is rotated from 0 to 360 Degrees in 180 separate steps, providing a reading every 2 Degrees. The calibration certificate then compares the fixed wind velocity of the wind tunnel to the readings collected by the unit at each step as a percentage error.
£503.37
or call us for a quote