9 Trouble-shooting
52 of 64
Hya-Rain/Hya-Rain N
How to avoid pressure surges
Increasing the suction line
diameter
DIN 1988, Part 3, stipulates that for withdrawal rates > 0.5
l
/
s
an inside pipe diameter
of at least 20 mm must be selected.
Setting of the pressure
reducer
Pressure surges occur whenever the pressure differences exceed 2 bar. If the pressure
gauge indicates a pressure of 5 bar with the valve closed, and this pressure drops to
2.5 bar when the valve is opened, the pressure applied when the valve is closed must
be reduced by at least 1 bar.
Eliminating pressure surges
by throttling the flow
If an isolating valve or a pressure reducer is fitted in the mains water supply line
upstream of the system, the valve/reducer must be throttled until the pressure surge
is eliminated. The drawback of this method is the low mains water back-up flow rate.
It must be checked if the mains water back-up flow rate is sufficient to meet standard
consumption requirements. The lack-of-water monitoring equipment must not trip in
mains water mode when the max. quantity of water that can be withdrawn is
withdrawn. If the lack-of-water monitoring equipment trips, the discharge-side flow
rate must be throttled.
Membrane-type
accumulator
Fit an 8-litre membrane-type accumulator in the pipe upstream of the system inlet.
Such an accumulator will attenuate extreme pressure drops in small-diameter pipes
and absorb surges without throttling the flow rate.
