11 Appendix
RMS 621
68
Hauser
•
Result using the improved or fully compensated differential pressure method:
Operating volume: 3140 m
3
/h Mass flow: 14.8 t/h (density: 4.71 kg/m)
The measurement error using the traditional flow measurement method is approx. 27%.
If the DPT is scaled to "Mass" (this means a little compensation possible), the
total error would
be approx. 39%.
Splitting Range (measurement range expansion)
The measurement range of a differential pressure transmitter lies in the range of 1:3 to 1:7. This
function offers the possibility to expand the measurement range of the flow measurement to 1:20
by using up to three differential pressure transmitters per flow measurement point.
Hint of the set-up:
1.
Select flow/splitting range 1 (2,3)
2.
Define the signal type and select the differential pressure transmitters (valid for all differential
pressure transmitters!)
3.
Select the connection terminals for the transmitters and define the respective measurement
range.
Range 1: Transmitter with the smallest measurement range
Range 2: Transmitter with the next highest measurement range, etc.
4.
Set up "Curve, Units, Format, Sums, Pipe data etc." (valid for all transmitters)
!
Note!
For Splitting Range operation differential pressure transmitters that transmit a current > 20 mA (<
21 mA) on exceeding the measurement range must be used. The change between measuring ranges
is fully automatic (hysteresis in the threshold point).
Fig. 27:
Splitting range operation
Mean value calculation (averaging)
The mean value calculation function offers the possibility to generate an input signal from a number
of sensors positioned at different points and then calculate the mean value of these. This function is
helpful when a number of measurement points are required on a plant in order to calculate the
measurement point accurately enough. Example: Application of a number of Pitot tube sensors for
flow measurement in a pipe line that has either not got enough inflow length or is of a large cross
section area.
Mean value calculation is available for pressure, temperature and flow (differential pressure) inputs.
11.2.2
Correction tables
Flow meters deliver an output signal proportional to the flow rate. The relationship between the
output signal and the flow can be described in a so called curve. The flow of a transmitter does not
always accurately follow this curve over the total measurement range. This means that the flow
Содержание RMS621
Страница 1: ...BA127R 09 en 08 04 510 04788 Software Version 2 0 Operating manual RMS 621 Energy manager ...
Страница 6: ...RMS 621 6 Endress Hauser ...
Страница 23: ...RMS 621 5 Operation Endress Hauser 23 5 1 2 Display Quick Setup ...
Страница 88: ......
Страница 90: ...www endress com worldwide BA 127R 09 en 08 04 510 04788 FM SGML6 0 ...