60
There should be some strategy employed to prevent the PRV being driven into making
chaotic (frequent) pressure changes:
•
Make a careful consideration as to the difference should exist between the Low and
High thresh
olds, (this is commonly known as “hysteresis”).
Between the two thresholds there will be no change; crossing a threshold is
required to initiate a change.
If the Low Flow and High Flow settings are too close, frequent pressure changes
could occur when the network flow is hovering around these values.
•
Use
the “Ave” setting to smooth out any over
-reactiveness (increasing the value can
delay any target pressure changes until water demand has consistently changed).
e.g. With the settings shown (above), pressure will be High when it increases past
2988 l/s and will change to Low when it falls below 972 l/s.
IDT will detect an error situation for certain
situations, such as trying to program
unworkable settings within the unit.
The installer is responsible for choosing
suitable values, based on both the network
characteristics and the desired behaviour of
the PRV.
(IDT does not give any warning if the installer
has chosen inappropriate values for the
characteristics of the network).
WARNING:
This equipment should be installed, adjusted, and serviced by qualified
water industry maintenance personnel familiar with the construction and operation of
the equipment and the hazards involved. Failure to observe this precaution could result
in damage to the water network.