Performance Check - vectus ALNOR Balometer Jr. Manuel Du Propriétaire

PERFORMANCE CHECK

When checking the performance of the Balometer Jr., first verify that the
unit has been properly adjusted to zero. If the calibration is to be
checked, a reference flow standard at least 5 times more accurate than the
Balometer Jr. should be used. Flow standards that may be used for this
purpose include orifice plates or laminar flow elements. These devices
require accurate pressure and temperature reading instruments to measure
actual flow volume.
If the Balometer Jr. is checked against a velocity standard such as a Pitot-
static probe or thermal anemometer, you should be aware that this may
introduce errors. If a velocity standard is used, the average velocity must
be obtained by taking a traverse.* The accuracy of the average reading is
dependent on the flow uniformity, the number of readings in the average
and the accuracy of the velocity reading instrument. This average
velocity reading must then be multiplied by the area over which the
traverse was taken. If this area is not accurately measured, additional
errors in the final flow volume reading will result.
Finally, air flow instrumentation is often dependent on environmental
conditions such as temperature, atmospheric pressure, humidity and even
turbulence. These conditions can have very different effects on various
instrument types. Caution must be exercised when making comparisons.
A traverse is a set of velocity readings taken in a prescribed geometric pattern which
*
will provide an overall velocity value when averaged together. Any of TSI's velocity
measuring instruments can be used for this purpose. The owner's manuals contain
instructions on how to perform the traverse.
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