Additional Information For Piston Pump/Pulsation Operating - ABB MAG-SM Instruction Bulletin

9.4

Additional Information for Piston Pump/Pulsation Operating

Parameter Entry
Submenu
Operating mode
Operating mode
Piston pump
Filter
on
Damping
5.0000 s
Electromagnetic Flowmeter Converter
The primary applications for the AC field flowmeters is for fast measurement processing of continuous
flows for single or multiphase fluids. If pulsation dampeners can be installed then the DC field flowme-
ters can usually be utilized. If the use of pulsation dampers is undesirable or impossible, then instru-
ments with higher magnetic field excitation frequencies must be employed. For metering the pulsating
flow after single stage piston, hose and diaphragm pumps the converter must be able to correctly
process the peak flowrates. These peaks seldom reach more than three times the average flowrate. As
long as the converter can linearly process these flowrate peaks and sufficient samples are measured,
the accuracy for longer totalizer periods of the measurement system is unaffected. Therefore the
parameter Piston Pump is to be selected in the Submenu Operating Mode. A digital filter is incorporated
in the converter especially for pulsating flows or noisy signals. It smooths the instantaneous display indi-
cations and a noisy output current. The damping value can be reduced when the filter is turned on. The
response time of the converter is not affected.
There is no relationship between the HART-Protocol and the filter and the damping.
The filter must be turned on and a damping value >2.4s should be set.
% Pulsation
Filter aus Filter Off
10
% Pulsation
Filter On
Filter ein
Output Signal
Ausgangssignal
Output Signal without Pulsation
2 % Pulsation Ausgangssignal ohne Pulsation
tion
60 10
Kolbenhübe/min
60
Kolbenhübe/min
51