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HE 5750 Operating Instructions
#371627 Version 1.1
14 Pre-pressure control
Note!
This function is integrated since
software version 2.17
.
The pre-pressure control regulates the cleaning pressure. This can either happen via
-
the central isolation valve
-
or via an external pressure control valve.
If the central isolation valve is used, the cleaning pressure can only be “refilled”.
The cleaning pressure cannot actively be released, but it reduces indirectly by the pulsing of
the cleaning valves. The advantage of this type of pressure equalisation is that a drop in the
cleaning nominal pressure has no immediate effect on the entire system.
During a cleaning cycle, a decreasing or increasing cleaning nominal pressure is immediately
compensated. If no cleaning cycle is active, there is no compensation of the cleaning nominal
pressure.
The following parameters are necessary for the pre-pressure control with central isolation
valve:
‘
System pressure On
’ (4.12)
-
activates the central isolation valve and
-
indicates the lead time or the time until the cleaning nominal pressure is reached
again after the cleaning cycle has been activated.
‘System pressure Off’
(4.13)
-
indicates the rest time for the cleaning valve before it is activated again.
If an external pressure control valve is used instead of a central isolation valve, the pre-
pressure control is done by scaling the cleaning nominal pressure.
In the process data pool (PDP), the following function codes are available:
-
IN: external pre-pressure nominal value
-
OUT: pre-pressure nominal value
-
OUT: pre-pressure nominal value scaled for external pressure control valve.
These codes can be transferred to the process level via 'SmartTool'.
