TESTO 440 - Page 36

3 Operation
34
- Units: mm or cm, mm
2
or cm
2
- Pitot Tube Factor: 0.00 to 1.00
- Correction Factor: 1% to 200%
- Volume Flow Unit: m
3
/h, cfm, l/s, m
3
/s
The Pitot tube factor for Pitot tubes is generally the same and must be
entered prior to starting measurement:
- Prandtl Pitot tubes (0635 2045, 0635 2145, 0635 2345): Pitot tube
factor: 1.00
- Straight Pitot tubes (0635 2043, 0635 2143, 0635 2243): Pitot tube
factor: 0.67
- Air flow velocity matrix (0699 7077): Pitot tube factor: 0.82
For Pitot tubes from other manufacturers, refer to the instruction
manual for the Pitot tube factor or ask your supplier.
In a multi-point measurement, a mean value is calculated from the
individual measuring values.
In a timed average measurement, a mean value is calculated over a
certain period.
Several points can be measured. This generates a timed average/multi-
point total mean value.
2
Use to select the required parameter and make settings.
3
Press
or to exit the menu.
Carrying out the measurement

A suitable probe is connected to the measuring instrument.
1 Define the channel parameters in the application menu.
Observe the minimum clearances to points of discontinuity:
- 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).
2 Insert the Pitot tube in the channel.