Pitot Tube And Pressure Probe (Testo 445); Thermal Anemometer Probes (Testo 445); Velocity Measurement - TESTO 445 Instruction Manual

Pitot tube and pressure probe (testo 445)

The measuring range is not symmetrical when the measurement
is carried out using differential pressure probes (see Technical
Connect silicone hose to the correct connection plug (obser-
ve + and - on the probes.)
When measuring velocity with the Pitot tube, it is better to use the
0638.1445 pressure probe on account of its optimum accuracy.
The measuring range extends to approx. 40 m/s. Velocity  is
calculated in the instrument using the pressure difference p in the
Pitot tube and based on the following formula:
m/s = S x
Press to activate the conversion. The "Parameter setting"
menu is displayed. m/s appears in the display when activated via
the button. Confirm the m/s ON setting with
The next step is to decide, using the
the volume flow is to be calculated immediately (m3/h ON) or not
(m3/h OFF). Confirm input with
Pitot tube factor S and the temperature, humidity and absolute
pressure parameters required to automatically calculate density
have to be set in the instrument configuration.
The Pitot tube factor for testo Pitot tubes is at a constant 1.00 and
does not need to be changed. If non-Testo Pitot tubes are used,
please ask your supplier for the factor and save it.

Thermal anemometer probes (testo 445)

The measuring principle of thermal anemometers with a heated
wire or heated ball sensor is based on the cooling down of the sen-
sor element via the air flow. The sensor element is heated to
100 °C for this purpose. The power needed to keep the sensor
constantly at this temperature is a measure of the strength of the
flow. According to this measuring principle, this probe requires a
heating up period after being switched on which appears as "Count
Down" in the display. Measuring in accordance with this measuring
principle depends on the ambient pressure. The absolute pressure
can be set in the instrument configuration menu.
28

7. Velocity measurement

data on page 35)
200000 x p [hPa]
rho [g/m 3 ]
button, as to whether
.
.