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Air Speed Calibrations
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The
National Institute of Standards and Technology provides calibration services
for air speed
instrumentation such as Pitot tubes, hot-wire or thermal anemometers, ultrasonic
animometers, cup anemometers, propeller anemometers, and the like.
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The calibration service
is performed in the dual test-section wind tunnel over a range of 0.15 m/s
to
40 m/s (0.34 miles per hour to 80 miles per hour) with a test section of 1.5
m by 2.1 m (5 ft by 7 ft).
The standard for air speed measurement at NIST is a fiber optic Laser Doppler
Anemometer (LDA),
which is calibrated with known velocities produced by a rotating disk. The
air speed calibrations are
done by direct comparison of the response of the instrument under test with
the response of a NIST
LDA. The uncertainty of the air speed standards shown in figure 1 as function
of air speed is
,where VLDA is the velocity from the LDA. To read more about our
facilities, see our Technical
Notes and Publications. The air temperature, relative humidity, and
atmospheric pressure in the wind tunnel during the calibration are also measured
and reported.
Figure
1. NIST Airspeed Uncertainty versus airspeed
Two calibration cycles are done separated by a shutdown. In each calibration
cycle, the air speed is measured
five times at each air speed set point. Thus a normal airspeed calibration
consists of the average of ten independent
measurements at seven to thirteen air speeds. An air speed calibration of
this type costs $2,684. Special tests of
airspeed instruments (19030S and 19040S) can be arranged at cost. Examples
include in-situ calibrations of airspeed
instrumentation, proving other airspeed measurement systems, tests where appropriate
scaling will allow the results to
be applicable to fluids other than air, and wind speed and wind direction
measurements.
Turnaround time for a single airspeed instrument is approximately 4
weeks:
1. Allow 2 weeks for shipping;
2. 1 week for set-up and data collection; and
3. 1 week for report writing and review.
However, please contact Mike Hall to schedule the calibration of your instrument(s).
To have your airspeed instrument(s) calibrated:
- Contact Mike Hall to schedule your calibration dates;
- Fax or mail a purchase order to Mike Hall following purchase order guidelines and choosing a Service ID Number which can be found in the NIST Calibrations User's Guide SP 250, and
- Ship your test measure to Mike Hall following
shipping
procedures.
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Mike Hall |
John
D. Wright |
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T.T. Yeh |
