Goulds Pumps 3910 11th ed. - IOM - Manual (Page 20)

Suction Head/Flooded Suction Conditions
1.
An isolation valve should be installed in the suction
line at least two (2) pipe diameters from the pump
suction to permit closing of the line for pump
inspection and maintenance.
2. Keep suction pipe free from air pockets.
3. Piping should be level or slope gradually downward
from the source of supply.
4. No portion of the piping should extend below pump
suction flange.
5. The size of entrance from supply should be one (1) or
two (2) sizes larger than the suction pipe.
6. The suction pipe must be adequately submerged below
the liquid surface to prevent vortices and air
entrainment at the supply.
DISCHARGE PIPING
Properly designed and installed discharge piping is a
necessity for trouble-free pump operation. Discharge
piping should be flushed BEFORE connection to the pump.
1. Isolation and check valves should be installed in
discharge line. Locate the check valve between
isolation valve and pump; this will permit inspection of
the check valve. The isolation valve is required for
priming, regulation of flow, and for inspection and
maintenance of pump. The check valve prevents pump
or seal damage due to reverse flow through the pump
when the driver is turned off.
2. Increasers, if used, should be placed between pump
and check valves.
3. Cushioning devices should be used to protect the pump
from surges and water hammer if quick-closing valves
are installed in system.
BYPASS PIPING
Systems that require operation at reduced flows for
prolonged periods should be provided with a bypass line
connected from the discharge side (before any valves) to
the source of suction.
A minimum flow orifice can be sized and installed in
bypass line to preclude bypassing excessive flows. Consult
nearest sales office or factory for assistance in sizing
orifice.
An automatic recirculation control valve and/or solenoid
operated valve should be considered if a constant bypass
(i.e. orifice) is not possible.
AUXILIARY PIPING
!
The mechanical seal must have an appropriate seal
flush system. Failure to do so will result in excess heat
generation and seal failure.
!
Cooling systems such as those for bearing
lubrication, mechanical seal systems, etc., where
provided, must be operating properly to prevent
excess heat generation, sparks, and premature
failure.
!
Sealing systems that are not self purging or self
venting, such as plan 23, require manual venting
prior to operation. Failure to do so will result in
excess heat generation and seal failure.
Auxiliary piping may be required for seal chamber cover
cooling, mechanical seal flush or other special features
supplied with the pump. Consult pump data sheet for
specific auxiliary piping recommendations.
If seal chamber cover cooling is required, follow guidelines
listed below.
1. Flows of 4 l/min. (1 GPM) will generally satisfy
cooling requirements.
2. Cooling water pressure should not exceed
7.0 kg/cm
2 (100 psig).
FINAL PIPING CHECK
After connecting the piping to pump:
!
The Preventive Maintenance section must be
adhered to in order to keep the applicable ATEX
classification of the equipment. Failure to follow
these procedures will void the ATEX classification
for the equipment.
!
Check alignment, per alignment criteria outlined
previously, to determine if pipe strain has affected
alignment. If pipe strain exists, correct piping.
20
3910-1
1th IOM 5/08