HND-F215
HND-F215 K07/0522
page 13
Flow measuring probes are 'free-jet calibrated', i.e. the diameter of the flow
channel has to be 5 times bigger than the diameter of the flow measuring head (=
approx. 5 cm, otherwise measuring errors up to 40 %).
When evaluating the measuring results please also note that in a channel the
flow speed is usually higher in the middle of the channel than at its edges.
Therefore, use appropriate tables to calculate air flow by means of flow speed.
Averaging for Flow Measurements:
When taking flow measurements fluctuations tend to be quite high. To be able to
display a stable measuring value two averaging functions have been integrated in
the instrument.
Continuous Averaging
The average value displayed has been calculated from the past few
measurements conducted during the averaging time set After the instrument has
been switched on the time remaining till expiration of the averaging time will be
displayed at the bottom line of the display. The min. and max. values memorized
refer to the minimum and/or maximum average value displayed.
Average Hold
As soon as the HND-F215 instrument has been switched on the device starts
calculating the average flow value during the averaging time. During measuring
the
current measuring value
will be shown in the top line of the display while the
bottom line shows the remaining measuring time. As soon as measurements
have been completed the
average value
will be displayed and the device will
switch to the HOLD mode. The min. and max. values memorized refer to the
minimum and/or maximum measuring value established during averaging.
To start a new measuring series press the key "Store" (key 6).
Additional Measurements with any NiCr-Ni-Temperature Probe at
T2:
Use temperature channel T2 to take measurements of medium temperature, for
example. The value shown is not an average value.
7.8 Notes for Special Functions
Zero displacement ('Offset')
A zero displacement can be carried out for each of the two temperature channels
T1 (HND-FF31 only) and T2:
displayed temperature = measured temperature - Offset
Standard setting: 'off' = 0.0°, i.e. no zero displacement will be carried out. The
zero displacement is mainly used to compensate for sensor deviations. Unless
'off' is set, this value will be displayed shortly after the device is switched on;
during operation it will be identified by means of the offset arrow in the display.
