61
Where
more
than
one
pump
is
provided
the
suction
pipes
may
only
be
inter-connected
if
they
are
fitted
with stop
valves
to
allow
each
pump
to
continue
operating
when
the
other
is
removed
for
maintenance.
The connections
shall
be
dimensioned
as
appropriate
for
the
flow
rate
required.
9.6.2.3
Suction
lift
conditions
The diameter of the suction pipe shall be no less than 80 mm. Furthermore, the diameter shall be such
that a velocity of 1,5 m/s is not exceeded when the pump is operating at maximum demand flow. This
velocity may be increased to 2,5m/s, if the pressure in the suction pipe is not more than 0,4 bar below
ambient pressure.
Where
there
is
more
than
one
pumpset
installed,
the
suction
pipes
shall
not
be
interconnected.
The
height
from
the
low
water
level
(see
8.3.5)
to
the
centre
line
of
the
pump
shall
not
exceed
3,2m.
The
suction
pipe
shall
be
positioned
in
the
tank
or
reservoir
in
accordance
with
figure
4
and
table
13
or figure
56
and
table
14,
as
appropriate.
A
foot
valve
shall
be
fitted
at
the
lowest
point
on
the
suction
pipe. Each
pump
shall
have
automatic
priming
arrangements
in
accordance
with
9.6.2.4.
9.6.2.4
Pump
priming
for
suction
lift
Each
pump
shall
be
fitted
with
a
separate
automatic
priming
arrangement.
The
arrangement
shall
consist
of
a
tank
situated
at
a
higher
level
than
the
pump
and
with
a
pipe
connection sloping
from
the
tank
to
the
delivery
side
of
the
pump.
A
non-return
valve
shall
be
fitted
to
this
connection. Figure
6
shows
two
examples.
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