General Pump LK Owner Manual - Manual (Page 12)

GENERAL PUMP
A member of the Interpump Group
LK SERIES
Page 12
The power take-off can be taken from either side of the pump. Generally the pump is supplied with the PTO shank for
the right-hand side (see fig. 6). To get the PTO from the left-hand side, she shaft end cover must be taken off and
remounted on the right hand side of the pump (see 2.1.1 in the repair manual). Vice-versa, the lug must be removed
from the right-hand side and inserted in the shank of the left-hand side.
9.3 Hydraulic Connections
In order to isolate the system from the vibrations produced by the pump, we recommend building the first section of the
hose near the pump (both for intake and delivery) with flexible hose. The solidity of the intake section must allow to avoid
deformation caused by the depressurization produced by the pump.
9.4 Pump Supply
LK pumps must always be installed under positive suction head, i.e. it must receive water falling from above or from a
supply under pressure, and it must never “suck” water from a lower level. The pumps can tolerate minimum water heads
of 1 meter. However, to obtain the best volumetric output and, especially, to prevent cavitation, the available net positive
suction head (NPSH avail), measured at the inlet flange at the head, must be greater than or equal to the values below:
9.5 Inlet Line
For the pump to function well, the inlet line must have the following characteristics:
1. Minimum internal diameter as indicated in the diagram in paragraph 9.8, and in any case equal or
greater than that of the pump head. Along the duct, avoid localized diameter reductions that may cause
pressure drops with subsequent cavitation. Absolutely avoid 90 0 elbows, connections with other hoses,
bottlenecks, counter-slopes, upside down “U” shaped curves, “T” connections.
2. The selected lay-out must allow to avoid cavitation.
3. It should be perfectly airtight, and built in a way that guarantees perfect sealing over time.
4. Avoid pump emptying when stopping (even partial emptying).
5. Do not use hydraulic-type fittings, 3 or 4 way fittings, adapters, etc., since they may hinder the pump’s
performance.
6. Do not install Venturi tubes or injectors for detergent intake.
7. Avoid the use of standing valves, check valves, or any other type of one-way valves.
8. Do not connect the by-pass line from the valve directly to the pump suction line.
9. Provide appropriate baffle plates inside the tank in order to avoid water flows coming from both the
by-pass and feeding lines may create turbulence near the tank’s outlet port.
10. Make sure that the suction line is perfectly clean inside before connecting it to the pump.
11. The pressure gauge for checking booster pressure must be installed near the plunger pump’s outlet
port, and always downstream of the filters.
LK36 LK40 LK45 LK50 LK55 LK60
NPSH
r
(m)
4 4.5 5.5 6.5 7.5 5
For pumps of greater capacity, i.e. LK50, LK55 and LK60, supply under pressure from a booster pump is strongly recom-
mended to avoid cavitation, due to the geometry of the hydraulic part and the high flow rates. The booster pump must
have a flow rate of at least double that of the rated flow rate of the plunger pump, and a pressure of between 30 and 44
PSI (2 and 3 bar). These supply conditions must be respected for any and all working systems.
Booster start-up must always be started before the plunger pump. In order to protect the pump, we
advise installing a pressure switch on the supply line downstream of the filters.