TESTO 480 - Page 33

6 Using the product
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• Thermal probes (incl. temperature measurement and possibly
humidity measurement) for low flow speeds
• 16 mm wheel measuring head (incl. temperature measurement)
for average flow velocities
• Pitot tube for measurements at high velocities and in heavily
contaminated flows with a high percentage of particles
Detailed background information on grid measurement and
carrying it out can be found in the Testo Ambient Air
Measurement for Practical Users field guide. You can
request a free copy or download it from www.testo.com.
Selecting a suitable measuring point
The main prerequisite for accurate measurement is the suitability of
the measuring point. Minimum distances from points of
discontinuity must be observed:
• From points of discontinuity upstream of the flow, observe a
clearance of at least six times the hydraulic diameter Dh = 4A/U
(A: channel cross-section, U: channel circumference).
• From points of discontinuity downstream of the flow, observe a
clearance of at least twice the hydraulic diameter Dh = 4A/U (A:
channel cross-section, U: channel circumference).
Preparing for measurement
✓ 16 mm wheel measuring head, thermal air flow measuring head
and humidity probe or Pitot tube is connected.
1. Switch the instrument on.
2. Create a new measuring point in Explorer under the required
measuring location.
3. Set the following parameters: