Tecfluid FLOMID-MX - Manual (Page 9)

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4.1.3 Measuring units
In this screen the measuring units should be introduced as follows:
M e a s u r i n g u n i t s
l / h
The cursor appears under the first letter. Using the
push button the character can be
changed from letter a to z and number 0 to 9 and some punctuation signs.
Once the required character is obtained, pressing the push button the cursor moves on to
the next character to be modified. On the last character (units of time) we can select between hours,
minutes or seconds. On pressing the
push button the data displayed on the screen will be stored in
memory and the next programming screen will appear.
4.1.4 Decimals
In this screen we can select the number of decimals (0, 1 or 2 decimals) for all the working
measuring units. When the number of decimals is changed all other parameters are automatically
changed and no extra reprogramming is required.
D e c i m a l s
> 1
4.1.5 Nominal flow rate
The nominal flow rate is the flow rate at a fluid speed of 5 m/s. This value should not be
confused with the maximum flow rate which is normally at about 10 m/s .
N o m i n a l f l o w r a t e
> 0 0 0 8 8 0 0 l / h
For the Flomid sensors, the nominal flow rate is printed on the sensor label (Qnom.). This value
is in and should be converted to the measuring units as selected in part 4.1.3.
For example, if we selected l/h as the measuring units and the sensor has a nominal flow rate
of 8.8 m3/h, then we must introduce the value in l/h, that is to say 8800 l/h.
For the Flomat sensors (insertion type), the nominal flow rate must be calculated for the pipe
diameter and for a fluid speed of 5 m/s.
Q in m3/h and DN in mm
4.1.6
Minimum flow rate (dropout)
In electromagnetic flow meters the error increases as the flow speed drops below 0.5 m/s. In
some cases there can be a very small flow signal although the liquid is stationary, and this can be
transmitted as flow and volume totalising. To avoid this happening we can program a minimum flow rate
(dropout) below which the instrument will not totalise or give a flow reading although it detects a small
flow signal.
The minimum flow rate is introduced as a percentage of the nominal flow rate (Qnom) as
specified on the sensor label.
M i n i m u m f l o w r a t e
> 0 5 %
2 DN · 0,014137 = Q