7 Operation
36 of 48
Hya-Duo D FL Compact
7.3.6 Flushing
NOTE
According to DIN 1988-600 automatic flushing must be effected once a week, if the
supply line exceeds a length of 10 x DN and a volume of 1.5 l. The flushing system
must be set to replace three times the water volume in the supply line. During the
flushing process the minimum flow velocity for DN 50 is 0.2 m/s; for larger nominal
diameters the minimum flow velocity is 0.1 m/s.
The break tank package booster set for fire fighting is fitted with a discharge-side
flushing system (solenoid valve
1
/
2
inch).
For flushing the inlet line provide a flushing system (e.g. solenoid valve) at the site.
The flushing duration of the inlet line must be determined and set using the timer in
the switchgear and controlgear assembly.
Determining the flushing duration
1. Determine the flow rate (Q) of the solenoid valve at minimum available inlet
pressure (p
Inl
).
0
1
2
3
4
5
6
7
8
0
1
2
Q [l/s]
p
z
u
l
[
b
a
r]
Fig. 8:
Flow diagram, solenoid valve: flow rate (Q) as a function of inlet pressure (p
Inl
)
2. Determine the flow velocity (V) at minimum available inlet pressure (p
Inl
).
Multiply the result with three times the volume of the inlet line.
ð
Nominal size ≤ DN 50: minimum flow velocity (V) = 0.2 m/s
ð
Nominal size > DN 50: minimum flow velocity (V) = 0.1 m/s
0
1
2
3
4
5
0
0,1
0,2
0,3
0,4
0,5
DN 80
DN 50
DN 65
V [m/s]
p
z
u
l
[
b
a
r]
Fig. 9:
Flushing process in the inlet line: flow velocity (V) as a function of inlet
pressure (p
Inl
)
3. Calculate the flushing duration.
Setting the discharge-side flushing system
ü
The overflow has been properly connected.
ü
The required flushing duration has been determined.
1. Set the timers in the duty system and in the stand-by system. Set the time and
duration for flushing in the switchgear and controlgear assembly (second
channel of the timer) in accordance with the supplied original operating
manual.
ð
The flushing water is discharged via the overflow.
