Grundfos VLSE Installation And Operating Instructions Manual Download Page 5

Page: 5 / 48

English (US)

4.4 Location

Locate the pump as close to the suction supply as possible.
Use the shortest and most direct suction piping practical. Refer to
section

4.9 Suction (inlet) piping

. Locate the pump below system

level wherever possible. This will facilitate priming, assure a
steady liquid flow, and provide a positive suction head. Make sure
sufficient NPSH (Net Positive Suction Head) is provided at the
suction end by considering the pump's location in relation to the
entire system. Available NPSH must always equal or exceed
required NPSH specified on the pump performance curve.
Always allow sufficient accessibility for maintenance and
inspection. Provide a clear space with ample head room for use
of a hoist strong enough to lift the pump/motor assembly.
Make sure a suitable power source is available for the pump
motor. Electrical characteristics should match those specified on
the motor data plate, within the limits covered in sections

5. Installation-electrical

and

6. Operation

. Avoid pump exposure

to sub-zero temperatures to prevent pump liquid from freezing.
If freezing conditions exist during shutdown periods, see sections

6.7 Short duration shutdown

and

6.8 Extended period shutdown

for specific recommendations.

4.5 Mounting of pump

Grundfos Type VLSE In-line centrifugal pumps may be mounted
on the equipment room floor, or suspended in the piping,
depending on the size and configuration of the pump.
The following instructions shall apply:

4.6 Floor mounted pumps (VLSE)

Pumps mounted on equipment room floors should be
permanently installed on a firm, concrete foundation, mounting
pad or spring isolation base of sufficient size to dampen any
vibration and prevent any deflection. Suitable anchor bolts shall
be used to secure the pump assembly to the pad or floor.

4.7 Suspended pumps (VLSE)

Pumps when properly supported, may be suspended in system
piping. Pipe supports must be used on piping immediately
adjacent to the pump. Pipe supports must be adequately sized to
support the weight of pump and piping, full of liquid, and shall be
designed to eliminate transmission of noise or vibration.
Grundfos Type VLSE In line pumps are designed to be mounted
in horizontal pipe runs with motor positioned vertically upward.

4.8 Piping - general

Both suction and discharge piping should be independently
supported and properly aligned so that no strain is transmitted to
the pump when flange bolts are tightened. Make sure piping is as
straight as possible, avoiding unnecessary bends and fittings.
Where necessary, use 45 ° or long-sweep 90 ° pipe fittings to
decrease friction loss. Where flanged joints are used, make sure
that inside diameters properly match and mounting holes are
aligned. Do not spring or force piping when making any
connections!

4.9 Suction (inlet) piping

The sizing and installation of suction piping is particularly
important. It must be selected and installed in a manner that
minimizes pressure loss and permits sufficient liquid flow into the
pump during starting and operation. Many NPSH problems can
be traced directly to improper design of suction piping systems.
Observe the following precautions when installing suction piping:
Suction piping should be as direct as possible, and ideally the
length should be at least ten times the pipe diameter.
Short suction piping can be the same diameter as the suction
opening. Longer piping should be one or two sizes larger
(depending on length), reducing to the diameter of the pump
suction opening. Use an eccentric reducer, with the eccentric side
down (fig.

) when reducing the pipe diameter to the diameter of

suction opening.

Fig. 2

Eccentric reducer usage

At no point should suction piping be smaller in diameter than the
pump suction opening. Avoid any high points, such as pipe loops
(fig.

), that may create air pockets and throttle the system or

produce erratic pumping.

Fig. 3

Eccentric reducer usage

&DXWLRQ

Do not use pump as a support for piping!
Use pipe hangers or other supports at proper
intervals to provide complete piping support near
the pump.