TESTO 645 - Pressure and Density Compensation Parameters

25
6. Instrument configuration
Parameters
025.0
Parameter
°C
Parameter setting for pressure and density compensation:
Humidity (g/kg, J/g), velocity (measured with thermal probes) and
CO
2
are pressure-dependent parameters.
Density is included in the measurement when velocity is measured
using a Pitot tube.
testo 445/645 automatically carries out pressure and density
compensation. Temperature, humidity and absolute pressure
must be entered.
3 parameters can be measured on location using a Testo
humidity/temperature probe (e.g. Part no. 0636.9740) and the
Testo absolute pressure probe (Part no. 0638.1645). See the
Chapter “Measuring absolute pressure” for more information on
measuring absolute pressure without an absolute pressure probe.
Density is automatically calculated by the instrument based
on these 3 values:
Factory
settings:
Note:
If the density set in the factory is taken as the basis, the
measurement error can be up to 10% of the measurement when
velocity is measured using a Pitot tube. Parameters must be
determined and set in the instrument in order to achieve exact
measurements.
The flashing position in the display can be set.
-
/
= Scroll/ = Next position -
= Confirm.
= Print parameter.
Pitot tube factor setting:
The factor for Pitot tubes from Testo is constantly at 1.00 and
does not need to be changed. If the Pitot tubes from other firms
are used, ask your supplier for the Pitot tube factor and save in
instrument.
Temperature
Humidity Density
Absolute pressure
Temperature 20 °C
Humidity 50 %RH Density 1199 g/m
3
Absolute pressure 1013 mbar
1.00
Parameter
Factor


1. Temperature
2. Humidity
3. Absolute pressure
5. Pitot tube factor
4. Density
(calculated)
(testo 445)
(testo 445)
(testo 445)
(testo 445)
(testo 445
testo 645)
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