Pentax HP Serie Instructions D'utilisation page 51

4. INSTALLATION
4.4 • DELIVERY AND SUCTION PIPES
4.4 • DELIVERY AND SUCTION PIPES
ATTENTION! Always ensure that the pipes can withstand the
maximum working pressure of the pump(see rating plate).
DANGER OF EXPLOSION!
Delivery and suction pipes and their accessories must not subject the pump
to any anomalous loads.
High bending loads from rigidly mounted, or misaligned pipe work, can
cause pump damage, broken flanges, etc....
Pipe work should be correctly aligned and supported to avoid vibration and
movement during the pump operation.
Delivery and suction pipes and their accessories must be clamped, so that
their weights and any dynamic or thermic loads are not transmitted to the
pump suction and delivery flanges.
The only sure way to avoid the above problems is to use a flexible joint, or a
short length of flexible pipe to connect any rigid pipe work to a pump
flange.
Delivery and suction pipes must have a bigger or equal diameter than the
pump diameter.
ATTENTION! Flange diameter of the pumps cannot be considered as
pipe diameter; this must be dimensioned depending on the plant
installation taking into account all frictional losses.
If the pipes are very long, pumps must be equipped with extension cou-
plings that can compensate possible thermic expansions.
Pipe flanges must be connected in parallel to the pump flanges.
To avoid relevant head losses, adapters having bigger diameter must be
manufactured with approx 8° expanding angle.
SUCTION PIPES (Fig. 23)
Suction pipe must be designed to avoid air cushions because they can cause
problems on the pump during operation.
Interception valve must be positioned from a distance of 10 times its nomi-
nal diameter.
Curves, valves and all the fittings on the suction pipes can produce charge
losses that can lead to an incorrect operation of the pump.
ATTENTION! Any welding scale, dust or other impurities left in
the suction line can damage pumps.
We recommend that all newly manufactured pipe work is thoroughly flushed
through and cleaned, before connecting to the pump.
– PUMP UNDER FEEDING
Piping horizontal parts must have a descending trend towards the pump
(minimum slope 2%)
If the pipes have a bigger diameter than the pump port, we recom mend
to use a reverse eccentric reduction.
– PUMP OVER FEEDING
Piping horizontal part must have an ascending trend towards the pump
(minimum slope 2%).
If necessary, the fittings with the pump port must have an eccentric reduc-
tion in normal position.
If suction piping is extended, we suggest using a siphon before the pump,
so that the fluid reaches the impeller only after filling the tube completely.
16