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6.7 External Synchronized Operation
This operation mode is used in the event that the measured matter does not flow continuously or the
interior of the detector is temporarily left empty due to the intermittent operation of the shifting pump to
the pipe line on which the density meter is installed. This mode is used to take measurements only when
operating the shifting pump.
To use this operation mode, it is necessary to connect the shifting pump operation and the contact signal
(no-voltage) to the external synchronized input signal pins beforehand.
6.7.1
Movement of the external synchronized operation
Pump operating status
(External contact)
Density measuring
status(Output)
The external synchronized operation, as shown in Fig. 6.7.1, is so designed that the density
measurement is executed only while the pump is being operated; and the density measurement is
suspended while the pump is shut down and the simulated output is issued during this time. The external
synchronized operation is effective in preventing the following inadequate phenomena.
(1) The pump shutdown causes solid matters to subside or float thus making it impossible to take density
measurements correctly.
(2) The pump shutdown may cause the fluid to escape from the tank or the piping system (where the density
meter is installed) thus either leaving it completely empty or insufficiently filled with fluid. In such a situation,
the measured value of the density meter falls into error such as full-scale excess, shift to the minus side, or
occurrence of fluctuation within major marginal error.
It takes time for the tank or the piping system (where the density meter is installed) to be filled
sufficiently with the measured matter after the pump is operated. Here, it is so arranged that the
measurement start after the "delayed time" that is set beforehand has elapsed since receiving the contact
signal linked with the pump operation. Make sure that the delayed time that is set is sufficient for the
whole process of the pipe length and flow, etc. from the pump to the density meter.
As the simulated value when the density measurement is suspended, it is possible to select from among
three options: "4mA", "density measured value immediately preceding the pump shutdown" and
"simulated output in setting mode". The default value is 4mA. However, make sure to select a simulated
output suitable to your system.
Pump shutdown (OFF)
Suspension of density
measurement
(Simulated output)
Delayed time
Fig.6.7.1 External synchronized Operation
65
Pump operation (ON)
Pump shutdown (OFF)
Execution of density
measurement
(Measured value
output)
6 F 8 A 0 7 8 7
Time
Time
Suspension of density
measurement (Simulated
output)
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