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Low pressure target is appropriate. It will then set the actuator to the required target
pressure.
The lower part of the Flow Control Settings
panel deal with data collection for making
the evaluation.
The “Sample Rate” determines how often a
flow measurement sample is taken for
evaluation,
for PRV controller purposes only
.
Some statistical function (average) is applied
to smooth out any fluctuation in the measurements which could cause rapid and
chaotic changes to the target pressure. Typically, the system samples every 10 seconds
and uses the average from the last 6 measurements to arrive at a target pressure.
(
“Flow Cal” in the above picture is a repeat of the calibration setting of the Flow channel.
e.g. Units per pulse, for a flow pulse counter interface. It does not require adjustment).
Since the pressure profile is dependent on
Flow, certain settings in Sentinel 2 define what
should happen if there is a fault detected in
the Flow meter:
The target pressure will be as per the setting
“Default Pressure”.
One condition that can register as a
flow-sensor fault is when there are no flow pulses detected for a time period.
This condition must exist for the time set in the “No Flow Timeout (mins)” field before
it is recognised as a fault.
(No specific alarm is generated for this condition, but it is included in the messages
delivered to the server during normal call-in).
The “table” for 2
-point flow control consists of just 2 values. These are the thresholds for
making the switch:
•
From High to Low pressure output
(“Low Flow l/s” setting), and
•
From Low to High pressure output
(“High Flow l/s” setting)
The most common use scenario for these settings is to reduce the PRV output pressure
during times of low water demand, such as during the night. Conversely, the PRV should
be switched to a higher output pressure when water demand increases, such as during
the day.
